Internet DRAFT - draft-schaad-plasma-service
draft-schaad-plasma-service
Network Working Group J. Schaad
Internet-Draft Soaring Hawk Consulting
Intended status: Standards Track February 14, 2014
Expires: August 18, 2014
Plasma Service Trust Processing
draft-schaad-plasma-service-05
Abstract
RFC TBD describes a new model and set of requirements to implement a
labeling system on Cryptographic Message Syntax (CMS) objects where
the entity in charge of doing the label enforcement is under the
control of a central authority rather than the recipient of the
object.
This document describes a protocol to be used by senders and
recipients of CMS objects to communicate with a centralized label
enforcement server. The document outlines how a client will get the
set of labels or policies that it can use for sending messages,
composes a secure CMS object with a label on it and gets the
necessary keys to decrypt a CMS object from the server. This
document is designed to be used with RFC TBD2 which describes the
extensions used in CMS objects to hold the label information.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 18, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
Schaad Expires August 18, 2014 [Page 1]
Internet-Draft EPS TRUST February 2014
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. XML Nomenclature and Name Spaces . . . . . . . . . . . . 4
1.2. Requirements Terminology . . . . . . . . . . . . . . . . 4
2. Components . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. XACML 3.0 . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. SAML . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3. WS-Trust 1.4 . . . . . . . . . . . . . . . . . . . . . . 6
3. Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Sender Processing . . . . . . . . . . . . . . . . . . . . 7
3.2. Recieving Agent Processing . . . . . . . . . . . . . . . 8
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 9
5. Plasma Request . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Authentication Element . . . . . . . . . . . . . . . . . 11
5.1.1. SAML Assertion . . . . . . . . . . . . . . . . . . . 13
5.1.2. WS Trust Tokens . . . . . . . . . . . . . . . . . . . 14
5.1.3. XML Signature Element . . . . . . . . . . . . . . . . 15
5.1.4. GSS-API Element . . . . . . . . . . . . . . . . . . . 16
5.2. xacml:Request Element . . . . . . . . . . . . . . . . . . 18
6. Plasma Response Element . . . . . . . . . . . . . . . . . . . 19
6.1. xacml:Response Element . . . . . . . . . . . . . . . . . 20
7. Role Token and Policy Acquisition . . . . . . . . . . . . . . 22
7.1. Role Token Request . . . . . . . . . . . . . . . . . . . 22
7.2. Request Role Token Response . . . . . . . . . . . . . . . 23
7.2.1. RoleToken XML element . . . . . . . . . . . . . . . . 25
7.2.2. Email Address List Options . . . . . . . . . . . . . 29
8. Sending An Email . . . . . . . . . . . . . . . . . . . . . . 29
8.1. Send Message Request . . . . . . . . . . . . . . . . . . 29
8.1.1. CMS Message Token Data Structure . . . . . . . . . . 30
8.1.2. XML Label Structure . . . . . . . . . . . . . . . . . 33
8.2. Send Message Response . . . . . . . . . . . . . . . . . . 35
8.3. XML Message Send Request . . . . . . . . . . . . . . . . 36
8.4. XML Message Send Response . . . . . . . . . . . . . . . . 37
9. Decoding A Message . . . . . . . . . . . . . . . . . . . . . 37
9.1. Requesting Message Key . . . . . . . . . . . . . . . . . 37
9.2. Requesting Message Key Response . . . . . . . . . . . . . 39
10. Plasma Attributes . . . . . . . . . . . . . . . . . . . . . . 40
Schaad Expires August 18, 2014 [Page 2]
Internet-Draft EPS TRUST February 2014
10.1. Data Attributes . . . . . . . . . . . . . . . . . . . . 41
10.1.1. Channel Binding Data Attribute . . . . . . . . . . . 41
10.1.2. CMS Signer Info Data Attribute . . . . . . . . . . . 41
10.1.3. S/MIME Capabilities Data Attribute . . . . . . . . . 42
10.1.4. EMAIL Recipient Addreses . . . . . . . . . . . . . . 42
10.1.5. Return Lockbox Key Information . . . . . . . . . . . 43
10.2. Obligations and Advice . . . . . . . . . . . . . . . . . 44
10.2.1. Signature Required . . . . . . . . . . . . . . . . . 45
10.2.2. Content Encryption Algorithm Required . . . . . . . 45
10.2.3. Lock Box Required . . . . . . . . . . . . . . . . . 45
11. Certificate Profiles . . . . . . . . . . . . . . . . . . . . 46
12. Message Transmission . . . . . . . . . . . . . . . . . . . . 47
13. Plasma URI Scheme . . . . . . . . . . . . . . . . . . . . . . 47
13.1. Plasma URI Schema Syntax . . . . . . . . . . . . . . . . 47
13.2. Definition of Operations . . . . . . . . . . . . . . . . 47
14. Security Considerations . . . . . . . . . . . . . . . . . . . 47
14.1. Plasma URI Schema Considerations . . . . . . . . . . . . 48
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48
15.1. Plasma Action Values . . . . . . . . . . . . . . . . . . 48
15.2. non . . . . . . . . . . . . . . . . . . . . . . . . . . 49
15.3. Port Assignment . . . . . . . . . . . . . . . . . . . . 50
16. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 50
17. References . . . . . . . . . . . . . . . . . . . . . . . . . 51
17.1. Normative References . . . . . . . . . . . . . . . . . . 51
17.2. Informative References . . . . . . . . . . . . . . . . . 52
Appendix A. XML Schema . . . . . . . . . . . . . . . . . . . . . 53
Appendix B. Example: Get Roles Request . . . . . . . . . . . . . 57
Appendix C. Example: Get Roles Response . . . . . . . . . . . . 58
Appendix D. Example: Get CMS Token Request . . . . . . . . . . . 59
Appendix E. Example: Get CMS Token Response . . . . . . . . . . 61
Appendix F. Example: Get CMS Key Request . . . . . . . . . . . . 61
Appendix G. Example: Get CMS KeyResponse . . . . . . . . . . . . 62
Appendix H. Enabling the MultiRequests option . . . . . . . . . 62
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 63
1. Introduction
RFC TBD [I-D.freeman-plasma-requirements] describes a new model and
set of requirements to implement a labeling system on Cryptographic
Message Syntax (CMS) objects where the entity in charge of doing the
label enforcement is under the control of a central authority rather
than the recipient of the object.
This document describes a protocol to be used by senders and
recipients of CMS objects to communicate with a centralized label
enforcement server. The document outlines how a client will get the
set of labels or policies that it can use for sending messages,
composes a secure CMS object with a label on it and gets the
Schaad Expires August 18, 2014 [Page 3]
Internet-Draft EPS TRUST February 2014
necessary keys to decrypt a CMS object from the server. This
document is designed to be used with RFC TBD [I-D.schaad-plasma-cms]
which describes the extensions used in CMS objects to hold the label
information.
1.1. XML Nomenclature and Name Spaces
The following name spaces are used in this document:
+-----+------------------------------------------+------------------+
| Pre | Namespace | Specification(s) |
| fix | | |
+-----+------------------------------------------+------------------+
| eps | http://ietf.org/2011/plasma/ | This |
| | | Specification |
| | | |
| wst | http://docs.oasis-open.org/ws-sx/ws- | [WS-TRUST] |
| | trust/200512 | |
| | | |
| xac | http://docs.oasis- | [XACML] |
| ml | open.org/xacml/3.0/xacml-3.0-core-spec- | |
| | cs-01-en.html | |
| | | |
| ds2 | http://www.w3.org/2000/09/xmldsig# | [XML-Signature] |
| | | |
| xs | http://www.w3.org/2001/XMLSchema | [XML-Schema1 |
| | | ][XML-Schema2] |
+-----+------------------------------------------+------------------+
1.2. Requirements Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
When the words appear in lower case, their natural language meaning
is used.
2. Components
In designing this specification we used a number of pre-existing
specifications as building blocks. In some cases we use the entirety
of the specification and in other case we use only select pieces.
Schaad Expires August 18, 2014 [Page 4]
Internet-Draft EPS TRUST February 2014
2.1. XACML 3.0
The XACML specification (eXtensible Access Control Markup Language)
[XACML] provides a framework for writing access control policies and
for creating standardized access control queries and responses. The
request and response portion of the specification is used to build
the request (Section 5.2) and response (Section 6.1) messages in this
specification. The structure for writing the access control policies
is out of scope for this document, but XACML is one of the
possibilities that can be used for that purpose.
2.2. SAML
A number of different methods for carrying both identification and
attributes of the party requesting access is permitted in this
specification. SAML is one of the methods that is permitted for that
purpose.
SAML has defined three different types of assertions in it's core
specification [OASIS-CORE]:
o Authentication: The assertion subject was authenticated by a
particular means at a particular time.
o Attribute: The assertion subject is associated with the supplied
attributes.
o Authorization Decision:[[CREF1: I don't see Plasma using this type
--Trevor]] A request to allow the assertion subject to access the
specified resource has been granted or denied.
While a PDP can use an Authorization Decision as input, this is
unexpected and MAY be supported. In addition there are three
different ways that the subject of a SAML statement can be
identified:
o A bearer statement: These statements are belong to anybody who
presents them. The owner is required to take the necessary
precautions to protect them.
o A holder of key statement: These statements belong to anybody who
can use the key associated with the statement.
o Subject match:[[CREF2: What about attribute match? --Trevor]]
These statements can be associated to an identity by matching the
name of the entity.
Schaad Expires August 18, 2014 [Page 5]
Internet-Draft EPS TRUST February 2014
We cannot pass a SAML assertion with attributes as a single attribute
in the XACML request as XACML wants each of the different attributes
to be individually listed in the request. This greatly simplifies
the XACML code, but means that one needs to do a mapping process from
the SAML attributes to the XACML attributes. This process has been
discussed in Section 2 of [SAML-XACML]. This mapping process MUST be
done by a trusted agent, as there are a number of steps that need to
be done including the validation of the signature on the SAML
assertion. This process cannot be done by the PEP that is residing
on the Plasma client's system as this is considered to be an
untrusted entity by the Plasma system as a whole. One method for
this to be addressed is to treat the Plasma server as both a PDP (for
the Plasma client) and a PDP for the true XACML policy evaluator. In
this model, the Plasma server becomes the trusted PEP party and has
the ability to do the necessary signature validation and mapping
processes. A new XACML request is then created and either re-
submitted to itself for complete evaluation or to a third party which
does the actual XACML processing.[[CREF3: This sounds like we ignore
the mapping on the wire. There is no reason to mandate the mapping
occurs inside the PDP. --Trevor]]
2.3. WS-Trust 1.4
The WS-Trust 1.4 [WS-TRUST] standard provides for methods for
issuing, renewing, and validating security tokens. This
specification uses only a small portion of that standard,
specifically the structure that returns a trust token from the issuer
to the requester.
This specification makes no statements on the content and format of
the token returned from the Plasma server to the Plasma client in the
wst:RequestSecurityTokenResponse field. These tokens may be
parseable by the client, but there is no requirement that the client
be able to understand the token. The token can always be treated as
an opaque blob by the client which is simply reflected back to the
server at a later time. The attributes that client needs to
understand in order to use the token, such as the life time, are
returned as fields of the token response.
TODO: need to discuss the content model and say what elements need to
be supported and what elements can be ignored -- safely.
3. Model
To be supplied from the problem statement document. [[CREF4: Should
one be able to create a policy on the fly for specific item where a
set of attributes can be defined by the sender of the message.
--Brian]]
Schaad Expires August 18, 2014 [Page 6]
Internet-Draft EPS TRUST February 2014
(1)(3) +----------+
+----------->|Sending |<------------+
| |Agent | |
(2) v +----------+ v
+----------+ ^ +---------+
|Email | | |Mail |
|Policy |<----------+ |Transfer |
|Service | |Agent |
+----------+ +---------+
() ^ +----------+ ^
| |Receiving | |
+----------->|Agent |<------------+
()() +----------+
Figure 1: Message Access Control Actors
List the boxes above and give some info about them.
Email Policy Service is the gateway controller for accessing a
message. Although it is represented as a single box in the
diagram, there is no reason for it to be in practice. Each of the
three protocols could be talking to different instances of a
common system. This would allow for a server to operated by
Company A, but be placed in Company B's network thus reducing the
traffic sent between the two networks.
Mail Transfer Agent is the entity or set of entities that is used to
move the message from the sender to the receiver. Although this
document describes the process in terms of mail, any method can be
used to transfer the message.
Receiving Agent is the entity that consumes the message.
Sending Agent is the entity that originates the message.
3.1. Sender Processing
We layout the general steps that need to be taken by the sender of an
EPS message. The numbers in the steps below refer to the numbers in
the upper half of Figure 1. A more detailed description of the
processing is found in Section 7 for obtaining the security policies
that can be applied to a messages and Section 8 for sending a
message.
1. The Sending Agent sends a message to one or more Email Policy
Services in order to obtain the set of policies that it can apply
to a message along with a security token to be used in proving
Schaad Expires August 18, 2014 [Page 7]
Internet-Draft EPS TRUST February 2014
the authorization. Details of the message send can be found in
Section 7.1.
2. The Email Policy Service examines the set of policies that it
understands and checks to see if the requester is authorized to
send messages with the policy.
3. The Email Policy Service returns the set of policies and an
security token to the Sending Agent. Details of the message sent
can be found in Section 7.2.
4. The Sending Agent selects the Email Policy(s) to be applied to
the message, along with the set of recipients for the message.
5. The Sending Agent relays the selected information to the Email
Policy Service along with the security token. Details of this
message can be found in Section 8.1.
6. The Email Policy Service creates the recipient info attribute as
defined in [I-D.schaad-plasma-cms].
7. The Email Policy Service returns the created attribute to the
Sending Agent. Details of this message can be found in
Section 8.2.
8. The Sending Agent composes the CMS EnvelopedData content type
placing the returned attribute into a KEKRecipientInfo structure
and then send the message to the Mail Transport Agent.
3.2. Recieving Agent Processing
We layout the general steps that need to be taken by the sender of an
EPS message. The numbers in the steps below refer to the numbers in
the lower half of Figure 1. A more detailed description of the
processing is found in Section 9.
1. The Receiving Agent obtains the message from the Mail Transport
Agent.
2. The Receiving Agent starts to decode the message and in that
process locates an EvelopedData content type which has a
KEKRecipientInfo structure with a XXXX attribute.
3. The Receiving Agent processes the SignedData content of the XXXX
attribute to determine that communicating with it falls within
accepted policy.
Schaad Expires August 18, 2014 [Page 8]
Internet-Draft EPS TRUST February 2014
4. The Receiving Agent transmits the content of the XXXX attribute
to the referenced Email Policy Service. The details of this
message can be found in Section 9.1.
5. The Email Policy Service decrypts the content of the message and
applies the policy to the credentials provided by the Receiving
Agent.
6. If the policy passes, the Email Policy Service returns the
appropriate key or RecipientInfo structure to the Receiving
Agent. Details of this message can be found in Section 9.2.
7. The Receiving Agent proceeds to decrypt the message and perform
normal processing.
4. Protocol Overview
The protocol defined in this document is designed to take place
between a Plasma server and a Plasma client. The protocol takes
place in terms of a request/response dialog from the client to the
server. A single dialog can consist of more than one request/
response message pair. Multiple round trips within allow a client to
provide additional authentication, authorization and attribute
information to the server.
Each dialog contains one or more action attributes specifying what
actions the client wishes the server to take. Depending on the
action requested, additional attributes may be present providing data
for the action to use as input. Finally, each dialog will contain
authentication and attributes supplied by one or more authorities
that the server can use either as input to the action or as input to
policy decisions about whether to perform the action.
The protocol MUST be run over a secure transport, the secure
transport is responsible for providing the confidentiality and
integrity protection services over the entire message. The protocol
allows for signature operations to occur on sub-sections of the
message structure, howewever this is used for creation of identity
proofs and not for integrity protection.
Multiple dialogs may be run over a single secure transport session.
Before a new dialog may be started, the previous dialog MUST have
completed to a state of success, failure or not applicable. A new
dialog MUST NOT be started after receiving a response with an
indeterminate status. If a new dialog is desired in these
circumstances, then the transport session MUST to be closed and re-
opened. [[CREF5: --- I want to say that TLS reconnect using caching
is OK here. Is that a reasonable statement? I don't think we want
Schaad Expires August 18, 2014 [Page 9]
Internet-Draft EPS TRUST February 2014
to say that the server will keep Plasma session data across TLS
sessions. --JLS]]
5. Plasma Request
The specification is written using XACML as the basic structure to
frame a request for an operation. The request for operations to
occur are written using XACML action items. This specification
defines actions specific to Plasma in a CMS environment. Other
specifications can define additional action items for other
environments (for example the XML encryption environment) or other
purposes. (Future work could use this basic structure to standardize
the dialogs between PDPs and PAPs or to facilitate legal signatures
on emails.)
In addition to the XACML action request there is a set of structures
to allow for a variety of authentication mechanisms to be used. By
allowing for the use of SAML and GSS-API as base authentication
mechanisms, the mechanism used is contained in a sub-system and thus
does not directly impact the protocol.
The request message uses a single XML structure. This structure is
the eps:PlasmaRequest object. The XML Schema used to describe this
structure is:
<xs:element name="PlasmaRequest" type="eps:RequestType"/>
<xs:complexType name="RequestType">
<xs:sequence>
<xs:element ref="eps:Authentication" minOccurs="0"/>
<xs:element ref="xacml:Request"/>
</xs:sequence>
<xs:attribute name="Version" type="xs:string" default="1.0"/>
</xs:complexType>
The RequestType has two elements in it:
Authentication is an optional element that holds the structures used
for doing authentication and authorization. Unless no
authentication is required by the Plasma server, the element is
going to exist for one or more requests in the dialog.
xacml:Request is a required element that contains the control
information for the action requested. The control information
takes the form of an action request plus additional data to be
used as part of the action request. The data and actions are to
be treated as self-asserted, that is they are deemed not to come
from a reliable source even in the event that an authentication is
successfully completed. As self-asserted values, Plasma servers
Schaad Expires August 18, 2014 [Page 10]
Internet-Draft EPS TRUST February 2014
need to exercise extreme care about which are included in the
policy enforcement decisions. As an example, it makes sense to
allow for the action identifier to be included in the policy
enforcement, but assertions about the identity of the subject
should be omitted. This element is taken from the XACML
specification.
For some operations, display string values are returned as part of
the response from the server. The xml:lang attribute SHOULD be
included in the RequestType element to inform the server as to what
language client wishes to have the strings in. The server SHOULD
attempt to return strings in the language requested or a related
language if at all possible.
5.1. Authentication Element
One of the major goals in the Plasma work is to detach the process of
authentication specifics from the Plasma protocol. In order to
accomplish this we are specifying the use of two general mechanisms
(SAML and GSS-API) which can be configured and expanded without
changing the core Plasma protocol itself. The authentication element
has two main purposes: 1) to process the authentication being used by
the client and 2) to carry authenticated attributes for use in the
policy evaluation.
When transporting the authentication information, one needs to
recognize that there may be a single or multiple messages in the
dialog in order to complete the authentication process. In
performing the process of authenticating, any or all of the elements
in this structure can be used. If there are multiple elements filled
out, the server can choose to process the elements in any order.
This means that the Plasma protocol itself does not favor any
specific mechanism. The current set of mechanisms that are built
into the Plasma specification are:
o SAML Assertions - many different types of SAML assertions are
supported. The specification uses both bearer and holder of key
assertions.
o X.509 Certificates can be used for the purpose of authentication
by creating a signature with the XML Digital Signature standard.
o GSS-API - the specification allows for the use of GSS-API in
performing the authentication process. The ABFAB mechanism in
GSS-API is specifically designed for use in a federated community
and allows for both authentication and attribute information to be
queried from the identity server.
Schaad Expires August 18, 2014 [Page 11]
Internet-Draft EPS TRUST February 2014
o WS-Trust tokens allow for much of the same type of information to
be passed as SAML assertions. The Plasma specification has been
designed mainly for the use of WS-Trust tokens to be used for
caching prior authentication sessions.
More than one authentication element can be present in any single
message. This is because a client may need to provide more than one
piece of data to a server in order to authenticate, for example a
holder of key SAML Assertion along with a signature created with that
key. Additionally a client may want to provide the server an option
of different ways of doing the authentication. In a federated
scenario, an X.509 certificate with a signature can be presented and
the server may not be able to build a trust path to it's set of trust
anchors. In this case the client may need to use the GSS-API/EAP
protocol for doing the authentication. The client may want to
provide the server with one or more SAML Assertion that binds a
number of attributes to it's identities so that the server does not
need to ask for those attributes at a later time. Finally, multiple
entities may need to be validated (for example the user and the
user's machine).
When transporting the attribute information, one needs to recognize
that there may be single or multiple messages in the dialog in order
to complete the authorization process. The server will return a
status code of urn:oasis:names:xacml:1.0:status:missing-attribute in
the event that one or more attributes are needed in order to complete
the authorization process. The details on how XACML returns missing
attribute information is found in Section 7.17.3 of [XACML]. When
the list of attributes is returned, the client has two choices: 1) It
can close the dialog, look for a source of the missing attributes and
then start a new dialog, 2) it can just get an assertion for the
missing attributes and send the new assertion as in a new request
message within the same dialog. The decision of which process to use
will depend in part on how long it is expected to take to get the new
attribute assertion to be returned.
The same authentication data does not need to be re-transmitted to
the server in a subsequent message within a single dialog. The
server MUST retain all authenticated assertion information during a
single dialog.
The schema for the Authentication element directly maps to the
ability to hold the above elements. The schema for the
Authentication element is:
Schaad Expires August 18, 2014 [Page 12]
Internet-Draft EPS TRUST February 2014
<xs:element name="Authentication" type="eps:AuthenticationType"/>
<xs:complexType name="AuthenticationType">
<xs:choice maxOccurs="unbounded">
<xs:element ref="saml:Assertion"/>
<xs:element name="GSSAPI" type="xs:hexBinary"/>
<xs:element name="RoleToken">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##any" processContents="lax"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element ref="ds2:Signature"/>
<xs:element name="Other">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##other"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
The schema allows for multiple authentication elements to occur in
any order. It is suggested, but not required, that the ds2:Signature
element occur after the authentication element that has an assoicated
key. This makes it easier for servers to make a one pass validate of
all authentication elements.
The Other element is provided to allow for additional authentication
elements, include SAML version 1.1, to be used.
5.1.1. SAML Assertion
SAML Assertions can provide authentication or attribute information
to the server. A SAML statement only needs to be provided once
during a single dialog, the server MUST remember all attributes
during the dialog.
When a SAML Assertion contains a SubjectConformation element using
the KeyInfoConfirmationDataType as a subject conformation element,
the confirmation shall be performed by the creation of an XML
Signature authentication element. The signature element shall be
created using an appropriate algorithm for the key referenced in the
SAML statement.
Schaad Expires August 18, 2014 [Page 13]
Internet-Draft EPS TRUST February 2014
Identify a SAML statement in the delegation/subject/environment space
- need text for this [[CREF6: I don't remember what this is supposed
to be anymore. --JLS]]
5.1.2. WS Trust Tokens
WS Trust tokens are used in two different ways by this specification.
They can be used as the primary introduction method of a client to
the server, or they can be used by the server to allow the client to
be re-introduced to the server in such a way that the server can use
cached information.
WS Trust tokens come in two basic flavors: Bearer tokens and Holder
of Key tokens. With the first flavor, presentation of the token is
considered to be sufficient to allow the server to validate the
identity of the presenter and know the appropriate attributes to make
a policy decision. In the second flavor some type of cryptographic
operation (usually a signature or MAC computation) is needed in
addition to just presenting the token. The Signature element
(Section 5.1.3) provides necessary infrastructure to permit the
cryptographic result to be passed to the server.
This document does not define the content or structure of any tokens
to be used. This is strictly an implementation issue for the servers
in question. This is because the client can treat the WS Token value
presented to it as an opaque blob.[[CREF7: Is this totally true?
Don't we need some kind of identifier so the server can indicate when
the token can be replayed in a subsequence request? E.g. give me
these attributes or a foo token. --trevor]] Only the servers need to
understand how to process the blob. However there are some
additional fields which can be returned in addition to the token that
need to be discussed:
wst:TokenType SHOULD be returned if more than one type of token is
used by the set of servers. If a token type is returned to the
client, the client MUST include the element when the token is
returned to the server.
wst:BinarySecret SHOULD be returned for moderate duration tokens.
If a binary secret is returned then the client MUST provide
protection for the secret value. When a binary secret has been
returned, then the client MUST create either a signature or MAC
value and place it into the Signature element Section 5.1.3.
[[CREF8: I don't know of any way to say use the asymmetric key
that you authenticated with originally - can this be done?
--JLS]].
Schaad Expires August 18, 2014 [Page 14]
Internet-Draft EPS TRUST February 2014
wst:Lifetime MUST be returned with the wsu:Expires element set. The
wsu:Created element MAY be included. The element provides the
client a way to know when a token is going to expire and obtain a
new one as needed.
5.1.3. XML Signature Element
When a holder of key credential is used to determine the attributes
associated with an entity, there is a requirement that the key be
used in a proof of possession step so that the Plasma server can
validate that the entity does hold the key. The credentials can hold
either asymmetric keys (X.509 certificates and SAML Assertions) or
symmetric keys (WS Trust Tokens and SAML Assertions) which use
Digital Signatures or Message Authentication Codes (MACs)
respectively to create and validate a key usage statement. The XML
signature standard [XML-Signature] provides an infrastructure to for
conveying the proof of possession information.
The signature is computed over the XACML request element as a
detached signature. When a signature element exists in the message,
the ChannelBinding attribute (Section 10.1.1) MUST be included in the
request. By the use of a value which is derived from the
cryptographic keys used in for protecting the tunnel, it is possible
for the server to verify that the authentication values computed were
done specifically for this specific dialog and are not replayed.
When creating either a signature or a MAC, the following statements
hold:
o The canonicalization algorithm Canonical XML 1.1 [XML-C14N11]
without comments MUST be supported and SHOULD be used in preparing
the XML node set for hashing. Other canonicalization algorithms
MAY be used.
o The signature algorithms RSAwithSHA256 and ECDSAwithSHA256 MUST be
supported by servers. At least one of the algorithms MUST be
supported by clients. The MAC algorithm HMAC-SHA256 MUST be
supported by both clients and servers. Other signature and MAC
algorithms MAY be supported.
o Set the additional attributes that must be included in a signature
- what should they be?
o If an xacml:Request element is referenced by an XML Signature
element, the xacml:Request element MUST include the ChannelBinding
token (Section 10.1.1) as one of the attributes.
Schaad Expires August 18, 2014 [Page 15]
Internet-Draft EPS TRUST February 2014
o The keys used in computing the authentication value need to be
identified for the recipient. For X509 certificates, the full raw
certificate will normally be included as part of the signature,
but MAY be referenced instead. For SAML assertions, the specific
assertion carrying the asymmetric key can be identified by TBD
HERE. In the event that symmetric keys are used by holder of key
assertions, the specific assertion will be identified by TBD HERE.
In these cases the server is expected to be able to associated the
key with the assertion by some means (either locally or perhaps
encrypted into the assertion).
5.1.4. GSS-API Element
GSS-API [RFC2743] provides a security services to callers in a
generic fasion, supportable with a range of underlying mechanisms and
technologies. GSS-API has been extended by providing a mechanism for
EAP [RFC7055] which is designed to work in a federated environment.
This effort was done by the Application Bridging for Federated Access
Beyond web (ABFAB) working group. In this document the mechanism is
referred to as ABFAB. This is the same type of environment that the
Plasma protocol is expected to operate as well.
GSS-API offers a number of security services that are not currently
used by the Plasma system. At this point in time we are only looking
at the initial authentiction methods and not using the message
encryption or encryption services.
TBD - rules for using GSS-API in general and the EAP version from
ABFAB particularly.
o How to build the name.
o Must use a secure tunnel for the outer EAP method and an
appropriate inner EAP method(s) to accomplish the required level
of authentication.
o Server query of attributes and specification of LOA to the EAP
IdP.
o Any additional Trust model items.
o How round trips are accomplished - the only case that a server
will send back an Authentication element is on return processing
of GSS-API messages.
Schaad Expires August 18, 2014 [Page 16]
Internet-Draft EPS TRUST February 2014
5.1.4.1. Generic Requirements
Not all GSS-API mechanisms have the required features to support the
necessary security that is needed by Plasma. GSS-API mechanisms need
to support the following features:
o The mechanism MUST support the binding of the TLS tunnel to the
authentication via channel binding.
o Either the mechanism MUST support mutual authentication or the TLS
tunnel MUST be usable to authenticate the server being talked to.
Anonymous TLS sessions can be use when mutual authentication is
provided by the GSS-API mechanism.
5.1.4.2. GSS-EAP Requirements
When forming a mechnism name for GSS-API the following guidelines
SHOULD be followed:
o The user-or-service string is "plasma" (all in lower case).
o The host name is to be provided. When obtained from the URL, the
host name is to be the entire host name in the URL.
o There are currently no service-specific options defined.
o The realm name is OPTIONAL. When obtained from the URL, the realm
name is omitted.
o Realm and host names should be prepared according to [RFC5891]
prior to passing them into GSS-API.
Clients MUST use a tunneling EAP method that supports channel binding
between the tunnel and the inner EAP methods. At this point in time
only the TEAP method [I-D.ietf-emu-eap-tunnel-method] provides the
necessary support. While any inner EAP method can be used, it is
strongly recommended that only those methods that support generation
of EMSK (extended master session keys) be used, however methods tht
only support generation of a MSK (master session key) can be used.
(A discussion of why EMSKs should be generated can be found in
[RFC7029].)
IdPs MUST support the EAP channel binding that is part of TEAP. At a
minimum the service name, host name and real names MUST be checked
for matches between the information provided by the TEAP channel
binding and the RADIUS attributes.
Schaad Expires August 18, 2014 [Page 17]
Internet-Draft EPS TRUST February 2014
5.1.4.3. GSS-API Channel Bindings
The calls to GSS_Init_sec_content and GSS_Accept_sec_context take a
chan_bindings parameter. The value is a GSS_CHANNEL_BINDINGS
structure [RFC5554].
The initiator-address-type and acceptor-address-type fields of the
GSS-CHANNEL-BINDINGS structure MUST be set to 0. The initiator-
address and acceptor-address fields MUST be the empty string.
The application-data field MUST be set to the channel binding value
defined in Section 10.1.1.
5.2. xacml:Request Element
The request for an action to be performed by the Plasma server along
with the data that needs to be supplied by the client in order for
the server to complete the action are placed into the xacml:Request
element of the request. This document defines a set of actions that
are to be understood by the Plasma server. One (or more) action is
to be placed in the request message.
In addition to the request for a specific action to occur, the client
can place additional attributes in the request as well. These
attributes are provided in order to assist the server either in
identifying who the various agents on the client side are or to
provide suggestions of attributes for using in making control
decisions. Any data provided by the client in this manner is to be
considered as a self-asserted value and to be treated as if it comes
from the client as oppose to a trusted attribute agent.
For convenience the schema for the xacml:Request element is
reproduced here:
<xs:element name="Request" type="xacml:RequestType"/>
<xs:complexType name="RequestType">
<xs:sequence>
<xs:element ref="xacml:RequestDefaults" minOccurs="0"/>
<xs:element ref="xacml:Attributes" maxOccurs="unbounded"/>
<xs:element ref="xacml:MultiRequests" minOccurs="0"/>
</xs:sequence>
<xs:attribute name="ReturnPolicyIdList" type="xs:boolean" use="required"/>
<xs:attribute name="CombinedDecision" type="xs:boolean" use="required"/>
</xs:complexType>
The RequestDefaults element of the XACML Request MUST be omitted by
the clients. If present servers MUST ignore the RequestDefaults
Schaad Expires August 18, 2014 [Page 18]
Internet-Draft EPS TRUST February 2014
element. The use of the MultiRequest element is current not defined
for a Plasma server and SHOULD be omitted by clients.
Clients MAY set ReturnPolicyIdList to true in order to find out which
policies where used by the server in making the decision. Server MAY
ignore this field and not return the policy list even if requested.
A number of different entities may need to be identified to Plasma
server as part of a request. These entities include:
1. The subject making the request to the server.
2. The machine on the subject is using.
3. The entity the subject is acting for. Converse about Delegation.
6. Plasma Response Element
There is a single top level structure that is used by the server to
respond to a client request.
The XML Schema used to describe the top level response is as follows:
<xs:element name="PlasmaResponse" type="eps:ResponseType"/>
<xs:complexType name="ResponseType">
<xs:sequence>
<xs:element ref="xacml:Response"/>
<xs:element ref="eps:PlasmaReturnToken" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="Version" type="xs:string" default="1.0"/>
</xs:complexType>
<xs:element name="PlasmaReturnToken" type="eps:PlasmaReturnTokenType"/>
<xs:complexType name="PlasmaReturnTokenType">
<xs:sequence>
<xs:any namespace="##any" processContents="lax"/>
</xs:sequence>
<xs:attribute name="DecisionId" type="xs:string"/>
</xs:complexType>
A Plasma Response has two elements:
xacml:Response is a mandatory element that returns the status of the
access request.
PlasmaReturnToken is an optional element to return a token. These
tokens represent the answer, for a success, of the request. If
multiple tokens are being returned, then the element will occur
mutiple times.
Schaad Expires August 18, 2014 [Page 19]
Internet-Draft EPS TRUST February 2014
A Plasma Return Token is a wrapper for the actual token being
returned. The returned token may be any content. This document
defines the following elements that are to be returned in this
location
o RoleToken - used to return roles.
o CMSMessageToken - used to return one or more CMS RecipientInfo
strucutures.
o CMSKeyToken - used to return either a CMS RecipientInfo structure
or a bare content encryption key.
The PlasmaReturneTokenType has an optional attribute DecisionId.
This attribute is used when in the case multiple requests are made at
the same time in order to assoicate the rquest and the response
tokens.
6.1. xacml:Response Element
The xacml:Response element has the ability to return both a decision,
but additionally information about why a decision was not made.
The schema for the xacml:Response element is reproduced here for
convenience:
<xs:element name="Response" type="xacml:ResponseType"/>
<xs:complexType name="ResponseType">
<xs:sequence>
<xs:element ref="xacml:Result" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:element name="Result" type="xacml:ResultType"/>
<xs:complexType name="ResultType">
<xs:sequence>
<xs:element ref="xacml:Decision"/>
<xs:element ref="xacml:Status" minOccurs="0"/>
<xs:element ref="xacml:Obligations" minOccurs="0"/>
<xs:element ref="xacml:AssociatedAdvice" minOccurs="0"/>
<xs:element ref="xacml:Attributes" minOccurs="0" maxOccurs="unbounded"/>
<xs:element ref="xacml:PolicyIdentifierList" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
The xacml:Response element consists of one child the Result.
The xacml:Response element consists of the following elements:
Schaad Expires August 18, 2014 [Page 20]
Internet-Draft EPS TRUST February 2014
xacml:Decision is a mandatory element that returns the possible
decisions of the access control decision. The set of permitted
values are Permit, Deny, Indeterminate and No Policy.
xacml:Status is an optional element returned for the Indeterminate
status which provides for the reason that a decision was not able
to be reached. Additionally it can contain hints for remedying
the situation. This document defines an additional set of status
values to be returned. Formal declaration may be found in
Section 15.
* gss-api indicates that a gss-api message has been returned as
part of the authentication process.
xacml:Obligations is designed to force the PEP to perform specific
actions prior to allowing access to the resource. If a response
is returned with this element present, the processing MUST fail
unless the PEP can perform the required action. A set of Plasma
specific obligations are found in Section 10.2. [[CREF9: What
about audit obligatiouns --Trevor]]
xacml:AssocatedAdvice is designed to give suggestions to the PEP
about performing specific actions prior to allowing access to the
resource. This element is not used by Plasma and SHOULD be
absent. If the response is returned with this element present,
processing will succeed even if the PEP does not know how to
perform the required action. A set of Plasma specific advice
elements are found in Section 10.2.
xacml:Attributes provides a location for the server to return
attributes used in the access control evaluation process. Only
those attributes requested in the Attributes section of the
request are to be returned. Since Plasma does not generally
supply attributes for the evaluation process, this field will
normally be absent.
xacml:PolicyIdentifierList provides a location to return the set of
policies used to grant access to the resource. This element is
expected to be absent for Plasma. [[CREF10: Should we ignore it
if present? --Trevor]][[CREF11: I don't think we need to say
anything about looking at it or ignoring it. While it would be
something for debugging, as a general rule the client does not
care which policies where evaluated and passed to grant access.
--JLS]]
Schaad Expires August 18, 2014 [Page 21]
Internet-Draft EPS TRUST February 2014
7. Role Token and Policy Acquisition
In order to send an email using a Plasma server, the first step is to
obtain a role token that provides the description of the labels that
can be applied and the authorization to send an email using one or
more of the labels. The process of obtaining the role token is
designed to be a request/response round trip to the Plasma server.
In practice a number of round trips may be necessary in order to
provide all of the identity and attributes to the Plasma server that
are needed to evaluate the policies for the labels.
When a Plasma server receives a role token request from a client, it
needs to perform a policy evaluation for all of the policies that it
arbitrates along with all of the options for those policies. In
general, the first time that a client requests a role token from the
server, it will not know the level of authentication that is needed
or the set of attributes that needs to be presented in order to get
the set of tokens. A server MUST NOT issue a role token without
first attempting to retrieve from an attribute source (either the
client or a back end server) all of the attributes required to check
all policies. Since the work load required on the server is expected
to be potentially extensive for creating the role token, it is
expected that the token returned will be valid for a period of time.
This will allow for the frequency of the operation to be reduced.
While the use of an extant role token can be used for identity proof,
it is not generally suggested that a new token be issued without
doing a full evaluation of the attributes of the client as either the
policy or the set of client attributes may have changed in the mean
time.
7.1. Role Token Request
The process starts by a client sending a server a role token request.
Generally, but not always, the request will include some type of
identity proof information and a set of attributes. It is suggested
that, after the first successful conversation, the client cache hints
about the identity and attributes needed for a server. This allows
for fewer round trips in later conversations. An example of a
request token can be found in Appendix B.
The role token request, as with all requests, uses the
eps:PlasmaRequest XML structure. The eps:Authentication MAY be
included on the first message and MUST be included on subsequent
authentication round trips.
A role token request by a client MUST include the GetRoleTokens
Plasma action request as an attribute of the xacml:Request element.
Details on the action can be found in section Section 15.1. When
Schaad Expires August 18, 2014 [Page 22]
Internet-Draft EPS TRUST February 2014
role tokens are requested, no additional data needs to be supplied by
the requester.
An example of a message requesting the set of policy information is:
<esp:PlasmaRequest>
<eps:Authentication>...</eps:Authentication>
<xacml:Request>
<xacml:Attributes Category="...:action">
<xacml:Attribute AttributeId="urn:plasma:action-id">
<xacml:AttributeValue
DataType="http://www.w3.org/2001/XMLSchema#string">
GetRoleToken</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
</xacml:Request>
</esp:PlasmaRequest>
7.2. Request Role Token Response
In response to a role token request, the Plasma server returns a role
token response. The response uses the eps:PlasmaResponse XML
structure. When a response is create the following should be noted:
An xacml:Decision is always included in a response. The values
permitted are:
Permit is used to signal success. In this case the response MUST
include one or more eps:RoleToken element.
Deny is used to signal failure. In this case the xacml:Status
element MUST be present an contain a failure reason.
Indeterminate is used to signal that a final result has not yet been
reached. When this decision is reached, the server SHOULD return
a list of additional attributes to be returned and SHOULD return
the list of role tokens that have been granted based on the
attributes received to that point.
NotApplicable is returned if the Plasma server does not have the
capability to issue role tokens.
An example of a response returning the set of policy information is:
Schaad Expires August 18, 2014 [Page 23]
Internet-Draft EPS TRUST February 2014
<eps:PlasmaResponse>
<xacml:Response>
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:PlasmaTokens>
<eps:PlasmaToken>
<eps:PolicyList>
<eps:Policy>
Details of a policy
</eps:Policy>
... More policies ...
<wst:RequestSecurityTokenResponse>
<wst:TokenType>urn:...:plasma:roleToken</wst:TokenType>
<wst:RequestedSecurityToken>...</wst:RequestedSecurityToken>
</wst:RequestSecurityTokenResponse>
</eps:PolicyList>
</eps:PlasmaToken>
</eps:PlasmaTokens>
</eps:PlasmaResponse>
The process of getting role tokens has a problem that is not part of
the normal XACML design. It is possible to compute a partial result
based on the current set of attributes that have been supplied by the
client, while having other role tokens that cannot be provided to the
client since required attributes have not been provided. Since this
is not part of the standard XACML model, one only has a single access
/deny decision and if the attributes have not been provided then the
response would be deny, we need to look at it in a bit more detail
here.
In the process of discussions three different solutions to the
problem were considered:
A signal could be added that allows for the client to signal that
it cannot provide any more attributes to the server. This would
allow for a final decision to be provided, but would potentially
involve an additional round trip as the set of attributes can be
determined based on the set of attributes provided. Supplying new
attributes from the client can result in the server asking for new
attributes from the client. This is not currently supported by
the XACML model and there is no clear point where it would go into
our model.
The server can return a partial result on each round trip. This
maps directly onto the XACML model, but leads to some other
problems. It means that all of the policies must be designed such
Schaad Expires August 18, 2014 [Page 24]
Internet-Draft EPS TRUST February 2014
that adding a new attribute to the policy evaluation process will
not cause a policy that previously had been permitted is now
denied.
A method could be added that allows for the client to state that
it either does not have or does not know what an attribute is.
This method would allow for the server to make a definitive
answer, but it requires that one extra round trip be made to get
the final answer.
The normal mode that Plasma servers are expected to operate in is
returning incremental results, however they can also keep internal
state looking at what additional attributes are being provided by the
client. If the client provides no new attributes, then the server
can return a set of role tokens close down the conversation. If the
server expects to get all attributes from the back end, and just get
authentication from client, then it can return a set of role tokens
immediately without providing a list of attributes to the client for
it to try and satisfy.
7.2.1. RoleToken XML element
The eps:PlasmaReturnToken element is used to return a role token to
the client. Multiple role tokens can be returned by using multiple
eps:PlasmaReturnToken elements. Each role token returned contains
one or more policies that can be asserted, the role token, and
optionally one or more set of obligations or advice that need to be
observed when creating messages. Additionally the name of a Plasma
server to be used with the token can be included as well as
cryptographic information to be used with the token.
The schema used for the PlasmaTokens element is:
Schaad Expires August 18, 2014 [Page 25]
Internet-Draft EPS TRUST February 2014
<xs:element name="RoleToken" type="eps:RoleTokenType"/>
<xs:complexType name="RoleTokenType">
<xs:sequence>
<xs:element name="FriendlyName" type="xs:string"/>
<xs:element name="PDP" type="xs:anyURI" maxOccurs="unbounded"/>
<xs:choice>
<xs:element name="PolicyList">
<xs:complexType>
<xs:sequence>
<xs:element name="Policy" type="eps:PolicyDescType" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
<xs:element ref="wst:RequestSecurityTokenResponse"/>
<xs:element ref="xacml:Obligations" minOccurs="0"/>
<xs:element ref="xacml:AssociatedAdvice" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="PolicyDescType">
<xs:sequence>
<xs:element name="FriendlyName" type="xs:string"/>
<xs:element name="Options" minOccurs="0">
<xs:complexType>
<xs:complexContent>
<xs:extension base="xs:anyType">
<xs:attribute name="optionsType" type="xs:anyURI" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="PolicyId" type="xs:anyURI" use="required"/>
</xs:complexType>
The eps:RoleToken element contains the following items:
FriendlyName This element returns a descriptive name of the role as
a whole. The string returned SHOULD be selected based on the
language attribute on the request message. The string is suitable
for display to the user and should be indicative of the scope of
the role. Examples of role descriptive strings would be "Company
President", "Senior Executive", "Project X Electrical Engineer".
PDP The element provides one or more URLs to be used for contacting
a Plasma server for the purpose of sending a message. This
Schaad Expires August 18, 2014 [Page 26]
Internet-Draft EPS TRUST February 2014
element allows for the use of different Plasma servers for issuing
role tokens and message tokens. No ranking of the servers is
implied by the order of the URLs returned.[[CREF12: Should perhaps
rename to be more understandable - perhaps Server --JLS]]
PolicyList contains the description of one or more policies that can
be asserted using the issued role token. Any of the policies
contained in the list may be combined together using the policy
logic in constructing a label during the send message process.
Policy contains a single simple policy. This element is returned as
part of a read message token. The purposes is to allow for a
recipient to reply to a message that they would not normally be
able to assert.
PolicySet contains a complex policy. This element is returned as
part of a read message token The purpose is to allow for a
recipient to reply to a message that they would not normally be
able to assert.
wst:RequestSecurityTokenResponse contains the actual token itself.
xacml:Obligations This optional element contains a set of
obligations that the client is required to enforce in order to use
any of the policies listed when combined with the returned
security token. These obligations can include items such as
required algorithms or required operational steps such as
requiring a signature to be placed on the content. A policy can
be listed in multiple role tokens and the set of obligations may
be different depending on which role token is used. If the client
is unable to fulfill the obligations then it MUST NOT allow the
role token to be used.
xacml:AssociatedAdvice This optional element contains a set of
advice statements that the client is requested to enforce when
using any of the policies listed when combined with the returned
security token. This advice can include items such as encryption
or signature algorithms or operational steps such as requiring a
signature to be placed on the content. The client is SHOULD
fulfill the advice, however if it cannot fulfill the advice the
role token may still be used.
The eps:PolicyType type is used to represent the elements of a policy
to the client. The elements in this type are:
FriendlyName contains a display string that represents the policy.
This element is localized in response to the xs:lang attribute in
the eps:PlasmaRequest node.
Schaad Expires August 18, 2014 [Page 27]
Internet-Draft EPS TRUST February 2014
PolicyId contains a "unique" identifier for the policy. This is the
value that identifies the policy to the software. The type for
the value is defined as a URI.
Options This element is used to inform the client what the set of
options that need to be filled in as part of asserting the policy.
If the client software does not understand how to set the options
for the supplied type, then the client software MUST NOT allow the
user to assert the policy. The option structure is identified by
the URI in the optionsType attribute. This document defines one
option structure for holding a list of email addresses (section
Section 7.2.2). This option structure is used in the basic
policies defined in [PlasmaBasicPolicy].
When building the wst:RequestSecurityTokenResponse element, the
following should be noted:
A wst:RequestedSecurityToken element containing the security token
MUST be included. The format of the security token is not
specified and is implementation specific, it is not expected that
clients should be able to get useful information from the token
itself. Information such as lifetimes need to be provided as
addition elements in the response. Examples of items that could
be used as security tokens are SAML statements or encrypted record
numbers in a server database.
A wst:Lifetime giving the life time of the token SHOULD be
included. It is not expected that this should be determinable
from the token itself and thus must be independently provided.
There is no guarantee that the token will be good during the
lifetime as it may get revoked due to changes in the environment
(for example, if the policies are updated then all existing tokens
may need to be re-issued), however the client is permitted to act
as if it were. The token provided may be used for duration. If
this element is absent, it should be assumed that the token is
either a one time token or of limited duration.
Talk about cryptographic information - There are three different
types of crypto information that can be returned and we need to
figure out how to talk about them. These are 1) a symmetric key,
2) a new asymmetric key and 3) a pre-existing asymmetric key - for
example from the certificate used for authentication purposes.
There is probably good ways to do 1 and 2, but I don't know how to
talk about 3 at this point in time.
Schaad Expires August 18, 2014 [Page 28]
Internet-Draft EPS TRUST February 2014
7.2.2. Email Address List Options
Some policies are designed to be restricted to a set of explicitly
named people by the sender of the message. This policy is used for
the set of basic policies defined in [PlasmaBasicPolicy]. In these
cases the creator of the message specifies a set of recipients by
using email address names without any decoration.
The Email Address List Option is identified by the uri
"urn:ietf:params:xml:ns:plasma:options:emailAddrs". The type
associated with the structure is a string. The string contains a
space separated set of internalized email addresses. Domains SHOULD
be encoded as U-labels rather than using puny code.
All Plasma clients and servers MUST be able to create, parse and use
the Email Address List Option for any policy.
As of the release of this document, Plasma clients and servers are
not expected to understand any other options.
8. Sending An Email
After having obtained a role token from a Plasma server, the client
can then prepare to send an Email by requesting a message token from
the Plasma server. As part of the preparatory process, the client
will construct the label to be applied to the Email from the set of
policies that it can assert, determine the optional elements for
those policies which have options, generate the random key encryption
key and possible create the key recipient structures for the email.
Although this section is written in terms of a CMS Encrypted message,
there is nothing to prevent the specification of different formats
and still use this same basic protocol. An example of a send mail
request token can be found in Appendix D.
8.1. Send Message Request
The send message request is built using the eps:PlasmaRequest XML
structure. When building the request, the following applies:
o The eps:Authentication element MUST be included in the initial
message. The role token that authorizes the use of the label MUST
be included in the initial message. If the role token is
dependent on a cryptographic key for authentication, then that
authentication MUST be included in the initial message.
o The client MUST include an action attribute. This document
defines the GetSendCMSToken action attribute for this purpose.
Schaad Expires August 18, 2014 [Page 29]
Internet-Draft EPS TRUST February 2014
o The client MUST include a data attribute. This attribute contains
the information that is used to build the CMS Message token to be
returned. There MAY be more than one data attribute, but this
will not be a normal case. More details on this attribute are in
Section 8.1.1.
o If the client is using the XML Digital Signature element in this
message, then the client MUST include the cryptographic channel
binding token (Section 10.1.1) in the set of XACML attributes.
A message requesting that a CMS message token be created looks like
this:
<eps:PlasmaRequest>
<eps:Authentication>
<eps:WS_Token>
Role Token goes here
</eps:WS_Token>
<xacml:Request>
<xacml:Attributes Category="...:action">
<xacml:Attribute AttributeId="urn:plasma:action-id">
<xacml:AttributeValue>
GetSendCMSToken
</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="...:data">
<xcaml:Attribute AttributeId="urn:plasma:data-id">
<xacml:AttributeValue>
Label and keys
</xacml:AttributeValue>
</xcaml:Attribute>
</xacml:Attributes>
</xacml:Request>
</eps:Authentication>
</eps:PlasmaRequest>
8.1.1. CMS Message Token Data Structure
The message token data structure is used as an attribute to carry the
necessary information to issue a CMS message token. The schema that
describes the structure is:
Schaad Expires August 18, 2014 [Page 30]
Internet-Draft EPS TRUST February 2014
<xs:element name="GetCMSToken" type="eps:CMSTokenRequestType"/>
<xs:complexType name="CMSTokenRequestType">
<xs:sequence>
<xs:choice>
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
<xs:element name="Hash">
<xs:complexType>
<xs:sequence>
<xs:element ref="ds2:DigestMethod"/>
<xs:element ref="ds2:DigestValue" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="LockBox" type="eps:LockBoxType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="CEK" type="xs:hexBinary" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="LockBox" type="eps:LockBoxType"/>
<xs:complexType name="LockBoxType">
<xs:sequence>
<xs:element name="Subject" maxOccurs="unbounded">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:anySimpleType">
<xs:attribute name="type" type="xs:string" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:choice>
<xs:element name="CMSLockBox" type="xs:base64Binary"/>
<xs:element name="XMLLockBox" type="xenc:EncryptedKeyType"/>
<xs:any namespace="##other" processContents="lax"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
When used in an xacml:Attribute, the structure is identified by:
Category = "urn:ietf:params:xml:ns:plasma:data"
AttributeId = "urn:ietf:params:xml:ns:plasma:data:CMSTokenRequest"
DataType =
"urn:ietf:params:xml:schema:plasma:1.0#CMSTokenRequestType"
The elements of the structure are used as:
Schaad Expires August 18, 2014 [Page 31]
Internet-Draft EPS TRUST February 2014
Policy
This element contains a the policy to be applied to the message
when a single policy is used.
PolicySet
This element contains the policy to be applied to the message when
a combination of policies is to be applied.
Hash
This element contains the hash of the encrypted content of the
message that the policy is being applied to. The algorithm used
to compute the hash is contained in the DigestMethod element and
the value is contained in the DigestValue element.
LockBox
This optional element contains a pre-computed CMS recipient info
structure for a message recipient. This element may be repeated
when more than one lock box is pre-computed for recipients by the
message sender. This element is used in those cases where the
sender does not want to share the content encryption key with the
Plasma server and the sender has the ability to retrieve the
necessary keys for all of the recipients. If the #### obligation
was returned for the role token, then a recipient info lock box
MUST be created for the Plasma server and the CEK element MUST
absent. [[CREF13: Do we define this obligation or remove the
previous sentence? --JLS]]
CEK
This optional element contains the content encryption key (CEK) to
decrypt the message.
One or both of CEK and Recipients elements MUST be present.
The elements of the LockBoxType structure are:
Subject
This element contains a subject identifier. The element can occur
more than one time in situations where a subject has multiple
names or a key is used by multiple subjects. Since a CMS
recipient info structure does not contain a great deal of
information about the recipient, this element contains a string
which can be used to identify the subject. The format of the
subject name is provided by the required type attribute of the
element. All implementations MUST recognize
"urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress" as a name
type. [[CREF14: Call for other mandatory to implement name types
--JLS]] Other name types MAY be recognized.
Schaad Expires August 18, 2014 [Page 32]
Internet-Draft EPS TRUST February 2014
CMSLockBox
This element contains a base64 encoded CMS Recipient Info
structure. If the recipient info structure is placed here, it
MUST NOT be placed in the CMS EnvelopedData structure as well.
XMLLockBox
This element contains an EncryptedKeyType structure as defined by
the XML Encryption standard [W3C.WD-xmlenc-core1-20101130]. If
this recipien structure is placed here, it MUST NOT placed in the
XML EncryptedType struture as well.
In addition, the structure allows for other formats of encrypted data
structures to be included as well. Servers which do not recognize
the name space and data structure MUST return an unrecognized data
structure error and not process the request.
8.1.2. XML Label Structure
A client is allowed to build a complex label to be sent to the Plasma
server for evaluation. While there are some cases that a simple
single policy is applied to a message, it is expected that many, if
not most, messages will have more than one policy applied to it with
logical statements connected those policies.
The schema for specifying a label is:
<xs:element name="PolicySet" type="eps:PolicySetType"/>
<xs:complexType name="PolicySetType">
<xs:sequence>
<xs:choice maxOccurs="unbounded">
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
</xs:sequence>
<xs:attribute name="PolicyCombiningAlgId" type="xs:anyURI" use="required"/>
</xs:complexType>
<xs:element name="Policy" type="eps:PolicyType"/>
<xs:complexType name="PolicyType">
<xs:sequence>
<xs:any namespace="##any" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="PolicyId" type="xs:anyURI" use="required"/>
</xs:complexType>
The Policy and the PolicySet elements are used when specifying a
policy for a message depending on whether a single policy or multiple
policies are to be evaluated.
Schaad Expires August 18, 2014 [Page 33]
Internet-Draft EPS TRUST February 2014
The Policy element is used to specify a single policy to the server
along with any options that are defined for that policy. The Policy
element contains:
PolicyId
Is an attribute that contains the URI which identifies a specific
policy to be evaluated.
inner content
The content of the Policy element can be any XML element. The
content is to be the set of selected options for the policy (if
any exist). The schema applied to the content is based on the
policy selected.
The PolicySet element is used to specify a logical set of policies to
be applied to the message. This element allows one to specify
multiple policies along with a logic operation to combine them
together.
Policy
This element allows for a single policy and any policy specific
options for the policy to be specified. This element can occur
zero or more times.
PolicySet
This element allows for a logical set of policies to be
recursively evaluated. This element can occur zero or more times.
PolicyCombiningAlgId
This attribute specifies the operation to be used in combining the
elements of the tree together. This specification uses the XACML
policy combining algorithms from [XACML]. Servers and clients
MUST support the unordered Deny-Overrides and Permit-Overrides
policy combining rules. Servers SHOULD support all of the policy
combining rules defined in [XACML]. Clients are expected to use a
friendly name when displaying the policy combining rule to users.
When displaying strings to users, the following strings are
suggested:
AND Is used to represent either the ordered or unordered Deny-
Overrides combining algorithm.
OR Is used to represent either the ordered or unordered Permit-
Overrides combining algorithm.
Schaad Expires August 18, 2014 [Page 34]
Internet-Draft EPS TRUST February 2014
8.2. Send Message Response
In response to a send message request, the Plasma server returns a
send message response message. The response messages uses the
eps:PlasmaResponse XML structure. When the response message is
created, the following should be noted:
o The xacml:Decision is always included in the response. If the
'Permit' value is returned then a CMS Token Response element MUST
be present.
o The PlasmaReturnToken element with a eps:CMSToken content is
included with a permit response. The CMSToken contains one or
more CMS RecipientInfo objects to be included in the message sent.
An example of a message returning the set of policy information is:
<eps:PlasmaResponse>
<xacml:Response>
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:CMSToken>234e34d3</eps:CMSToken>
</eps:PlasmaResponse>
The schema use for returning a CMS token is:
<xs:element name="CMSToken" type="eps:CMSTokenResponseType"/>
<xs:complexType name="CMSTokenResponseType">
<xs:sequence>
<xs:element name="CMSLockBox" maxOccurs="unbounded">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:base64Binary">
<xs:attribute name="CMSType" type="xs:string"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
This schema fragment extends the Plasma response token type and
allows for the return of one or more base64 encoded RecipientInfo
structures. The Plasma server can return recipient info information
for any recipient that it pre-authorizes to receive the message (see
Section ### of [I-D.freeman-plasma-requirements] for examples of when
Schaad Expires August 18, 2014 [Page 35]
Internet-Draft EPS TRUST February 2014
this would occur). Additionally the Plasma server can return a
KEKRecipientInfo structure with the Plasma Other Key attribute. (For
details see [I-D.schaad-plasma-cms].) In some extremely rare cases
where the Plasma server can pre-authorize the entire set of
recipients , the KEKRecipientInfo structure with the Plasma Other Key
Attribute may not be included in the returned set of recipients. The
recipient info structure for the plasma server SHOULD be placed last
in the list of recipients infos.
The CMSTokenResponse type has the following:
CMSLockBox
This element contains the ASN.1 encoding for a CMS RecipientInfo
structure to be placed in the final message. This element will
occur multiple times if there are multiple CMS RecipientInfo
structures being returned from the server.
CMSType
This attribute of the RecipientInfo structure is an optional text
value that identifies the type of recipient info structure
returned. NOTE: This attribute is currently optional and is
likely to disappear if I do not find it useful.
8.3. XML Message Send Request
It is possible to do a send message request for an XML rather than a
CMS message structure. The send message request is built using the
eps:PlasmaRequest XML structure. When building the request, the
following applies:
o The eps:Authentication element MUST be included in the initial
message. The role token that authorizes the use of the label MUST
be included in the initial message. If the role token is
dependent on a cryptographic key for authentication, then that
authentication MUST be included in the initial message.
o The client MUST include an action attribute. This document
defines the GetSendXMLToken action attribute for this purpose.
o The client MUST include a data attribute. This attribute contains
the information that is used to build the XML Message token to be
returned. There MAY be more than one data attribute but that is
not a normal case. More details on this attribute are in
Section 8.1.1.
o If the client using the XML Digital Signature element in this
message, then the client MUST include the cryptographic channel
binding token (Section 10.1.1) in the set of the XACML attributes.
Schaad Expires August 18, 2014 [Page 36]
Internet-Draft EPS TRUST February 2014
8.4. XML Message Send Response
In response to a send message request, the Plasma server returns a
send message response message. The response messages uses the
eps:PlasmaResponse XML structure. When the response message is
created, the following should be noted:
o The xacml:Decision is always included in the response. If the
'Permit' value is returned then a XML Token Response element MUST
be present.
o The PlasmaReturnToken element with a eps:XMLToken content is
included with a permit response. The XMLToken contains one or
more XML EncyptedKey objects to be included in the message sent.
<xs:element name="XMLToken" type="eps:XMLTokenResponseType"/>
<xs:complexType name="XMLTokenResponseType">
<xs:sequence>
<xs:element name="XMLLockBox" maxOccurs="unbounded" type="xenc:EncryptedKeyType"/>
</xs:sequence>
</xs:complexType>
9. Decoding A Message
When the receiving agent is ready to decrypt the email, it identifies
that there is a KEKRecipientInfo object which contains a key
attribute identified by id-keyatt-eps-token. It validates the
signature, determines that communicating with the Plasma Service is
within local policy, and then sends a request to the service to
obtain the decryption key for the message.
In some cases the recipient of a message is not authorized to use the
same set of labels for sending a message. For this purpose a token
can be returned in the message along with the key so that recipient
of the can reply to the message using the same set of security
labels.
9.1. Requesting Message Key
The client sends a request to the Plasma server that is identified in
the token. For the CMS base tokens, the address of the Plasma server
to use is defined in [I-D.schaad-plasma-cms] this is located in the
aa-eps-url attribute.
The request uses the eps:PlasmaRequest XML structure. When building
the request, the following should be noted:
Schaad Expires August 18, 2014 [Page 37]
Internet-Draft EPS TRUST February 2014
o The xacml:Request MUST be present in the first message of the
exchange.
o The action used to denote that a CMS token should be decrypted is
"ParseCMSToken".
o The CMS token to be cracked is identified by "CMSToken"
o In the event that a reply to role token is wanted as well, then
that is supplied as a separate action. [[CREF15: We may want to
require that a reply token always be returned instead of just
returning it on demand. --jls]] In this case the action is
"GetReplyToken".
o If the client is using the XML Digital Signature element in this
message, then the client MUST include the cryptographic channel
binding token (Section 10.1.1) in the set of XACML attributes.
An example of a message returning the set of policy information is:
<eps:PlasmaRequest>
<eps:Authentication>...</eps:Authentication>
<xacml:Request>
<xacml:Attributes Category="...:action">
<xacml:Attribute AttributeId="..:action-id">
<xacml:AttributeValue>ParseCMSToken</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attribute Category="...:data">
<xacml:Attribute AttreibuteId="..:data-id">
<xacml:AttributeValue>
Hex encoded CMS Token Value
</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attribute>
</xacml:Request>
</eps:PlasmaRequest>
When used in an xacml:Attribute, the structure is identified by:
Category = "urn:ietf:params:xml:ns:plasma:data"
AttributeId = "urn:ietf:params:xml:ns:plasma:data:CMSToken"
DataType =
"urn:ietf:params:xml:schema:plasma:1.0#CMSTokenResponseType
Schaad Expires August 18, 2014 [Page 38]
Internet-Draft EPS TRUST February 2014
9.2. Requesting Message Key Response
In response to a message key request, the Plasma server returns a
decrypted key in the message key response. The response message uses
the eps:Plasma XML structure. When a response message is create the
following should be noted:
o If the value of xacml:Decision is Permit, then response MUST
include an eps:CMSKey element.
o For all other decision types the eps:CMSKey MUST be absent.
o If a reply token was requested and granted, then the response MUST
include an eps:PlasmaToken element. The eps:PlasmaToken element
MUST use the Label option
o Only the CEK and CMSLockBox elements in the choice are permitted
for the CMSKey tag name.
An example of a message returning the set of policy information is:
<eps:PlasmaResponse>
<xacml:Response>
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:CMSKey>
<eps:DisplayString>Label TExt</eps:DisplayString>
<eps:KEK>hex based KEK</eps:KEK>
</eps:CMSKey>
</eps:PlasmaResponse>
The schema for returning the decrypted key is:
Schaad Expires August 18, 2014 [Page 39]
Internet-Draft EPS TRUST February 2014
<xs:element name="CMSKey" type="eps:CMSKeyResponseType"/>
<xs:complexType name="CMSKeyResponseType">
<xs:sequence>
<xs:element name="DisplayString" type="xs:string"/>
<xs:choice>
<xs:element name="CEK" type="xs:base64Binary"/>
<xs:element name="CMSLockBox" type="xs:base64Binary"/>
<xs:element name="XMLLockBox" type="enc:EncryptedKeyType"/>
<xs:any namespace="##other" processContents="lax"/>
</xs:choice>
<xs:element ref="eps:RoleToken" minOccurs="0"/>
<xs:element ref="xacml:Attributes" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
This schema extends the Plasma response token type and restricts the
content to the listed elements. The values returned are:
DisplayString returns a localized display string for the policy(s)
which were applied to the message. The lang attribute on the
request is used to determine which language to use for this
string.
CEK returns the base64 encoded content encryption key.
CMSLockBox returns the content encryption key in the form of a CMS
RecipientInfo structure.
XMLLockBox returns the content encryption key in the form of an XML
Encrypted Key type.
RoleToken optionally returns a role token for replying to this
message.
Attributes optionally returns a set of attributes associated with
the message.
The structure allows for additional key types to be defined in other
schemas and returned in this structure as well. The set of allows
lock boxes to be returned is restricted by the XML tag nd not the
schema.
10. Plasma Attributes
In this document a number of different XACML attributes have been
defined, this section provides a more detailed description of these
elements.
Schaad Expires August 18, 2014 [Page 40]
Internet-Draft EPS TRUST February 2014
10.1. Data Attributes
10.1.1. Channel Binding Data Attribute
The channel binding data attribute is used to provide for a binding
of the TLS session that is being used to transport the Plasma
messages with the content of the Plasma requests themselves. There
is a need for the server to be able to validate that the
cryptographic operations related to holder of key statements be made
specifically for the current conversation and not be left over from a
previous one as a replay attack. By deriving a cryptographic value
from the shared TLS session key and signing that value we are able to
do so.
The channel binding value to be used is created by the TLS key
exporter specification defined in RFC 5705 [RFC5705]. This allows
for a new cryptographic value to be derived from the existing shared
secret key with additional input to defined the context in which the
key is being derived. When using the exporter, the label to be input
into the key exporter is "EXPORTER_PLASMA". The value to be derived
is 512 bits in length, and no context is provided to the exporter.
When used as an XACML attribute in a request:
The category of the attribute is
"urn:ietf:params:xml:ns:plasma:data".
The AttributeId attribute is
"urn:ietf:params:xml:ns:plasma:data:ChannelBinding".
The Issuer attribute is absent.
The DataType is either base64Binary or hexBinary
The same value is used for both the XACML channel binding data
attribute and the XM1L channel binding structure defined in
Section 5.1.3.
10.1.2. CMS Signer Info Data Attribute
In many cases a policy states that the client is required to sign the
message before encrypting it. The server cannot verify that a
signature is applied to the message and included, but we can require
that a signature be supplied to the server. This signature can then
be validated by the server (except for the message digest attribute
value), and the server can take a hash of the value and return it as
part of the key returned to a decrypting agent. This agent can then
validate that the signature is a part of the message and complain if
Schaad Expires August 18, 2014 [Page 41]
Internet-Draft EPS TRUST February 2014
it absent. This means we do not have an enforcement mechanism, but
we do have a way of performing an audit at a later time to see that
the signature operation was carried out correctly.
By requiring that a signature be supplied to the server as part of
the authentication process, the Plasma server can also be setup so
that the supplied signature is automatically feed into archival
operations. One way to do archiving is to use the data records
defined in [RFC4998].
The following applies when this data value is present:
The Category attribute is "urn:ietf:params:xml:ns:plasma:data".
The AttributeId attribute is
"urn:ietf:params:xml:ns:plasma:data:CMSSignerInfo".
The Issuer attribute is absent.
The DataType attribute is either base64Binary or hexBinary.
The data value is a CMSSignerInfo ASN.1 encoded object.
10.1.3. S/MIME Capabilities Data Attribute
Policies sometimes require that specific algorithms be used in order
to meet the security needs of the policy. This attribute allows for
an S/MIME Capabilities to be carried in a DER encoded
SMIMECapabilities ASN.1 structure to be transmitted to the client.
Details on how the S/MIME Capabilities function can be found in
[RFC5751].
The following attributes are to be set for the data value:
The Category attribute is "urn:ietf:params:xml:ns:plasma:data".
The AttributeId attribute is "urn:ietf:params:xml:ns:plasma:data
:SMIME-Capabilties".
The Issuer attribute is absent.
The DataType attribute is either base64binary or hexBinary.
10.1.4. EMAIL Recipient Addreses
In order for Plasma Servers to do pre-authentication in the Email
environment, it is necessary for the set of recipient addresses to be
delivered to the Plasma Server. The Plasma Server cannot reliably
Schaad Expires August 18, 2014 [Page 42]
Internet-Draft EPS TRUST February 2014
determine the set of recipients from the policies set on the message
as the set of recipients and the set of people authorized to view the
message may not have a one-to-one correspondance. People may be
authorized to see the content who are not recipients of the message
or visa versa.
The content of the attribute is a space separated list of email
addresses. Each address represents an Email recipient address that
the client will be placing in one or more of the recipient fields in
the message submission.
The following attributes are to be set for the data value:
The Category for the attribute is
"urn:ietf:params:xml:ns:plasma:data".
The AttributeId for the attribute is
"urn:ietf:params:xml:ns:plasma:data:SMTPRecipients".
The Issuer for the attribute is absent.
The DataType for the attribute is "http://www.w3.org/2001/
XMLSchema#string".
10.1.5. Return Lockbox Key Information
Some policies require that the content encryption key be transported
wrapped by another key rather than being sent in plain text. This
data value allows for this state to be indicated by the Plasma Server
to the Plasma Client, and for the client to provide the necessary key
information to the server.
This data attribute is returned as a missing attribute under the
circumstances where it is required by the policy and has not been
provided the client. This is an indication that the content
encryption key needs to be returned in a lock box rather than as
plain text. The Plasma Server MAY ignore this data value if it is
provided in a situation where the policy does not require that the
content encryption key be returned in an encrypted form.
The following attributes are to be set for this data value:
The Category for the attribute is
"urn:ietf:params:xml:ns:plasma:data".
The AttributeId for the attribute is
"urn:ietf:params:xml:ns:plasma:data:LockboxKey".
Schaad Expires August 18, 2014 [Page 43]
Internet-Draft EPS TRUST February 2014
The issue for the attribute is absent.
The DataType for the attribute is
"urn:ietf:params:xml:schema:plasma:1.0LockboxKey".
The schema for the type LockboxKey is:
<xs:complexType name="LockboxKey">
<xs:sequence>
<xs:choice>
<xs:element name="X509Certificate" type="xs:base64Binary"/>
<xs:element name="PGPKey" type="xs:base64Binary"/>
<xs:element ref="ds2:KeyInfo"/>
</xs:choice>
<xs:element name="Capabilities" type="xs:base64Binary" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
The fields of this structure are as follows:
X509Certificate holds a certificate with the public key to be used
in building the CMS Lockbox returned containing the content
encryption key.
PGPKey holds a PGP public key to be used in building the PGP lock
box returned containing the content encryption key.
ds2:KeyInfo holds a public key to be used in building a CMS lock box
returned containing the content encryption key.
Capabilities contains a base64 encoded SMimeCapablities ASN.1
structure allowing the client to advertise to the server which
algorithms are supported for building the lockbox structure. This
element is optional. If the element is omitted then the server
will make the selection of algorithms to be used based solely on
the pubic key.
10.2. Obligations and Advice
Obligations and advice consist of actions that the Plasma server
either requires or requests that the client PEP perform in order to
gain access or before granting access to the data. These normally
represent actions or restrictions that the PDP itself cannot enforce
and thus are not input attributes to the policy evaluation. The same
set of values can be used either as obligations or advice, the
difference being that if the PEP cannot do an obligation it is
required to change the policy decision.
Schaad Expires August 18, 2014 [Page 44]
Internet-Draft EPS TRUST February 2014
10.2.1. Signature Required
Many policies require that a message be signed before it is encrypted
and sent. Since the unencrypted version of message is not sent to
the Plasma server, the policy cannot verify that a signature has been
placed onto the signed message. The attribute is not for use as a
returned obligation from an XACML decisions, rather it is for a pre-
request obligations used in role responses (Section 7.2).
When used as an Obligation:
The ObligationId attribute is
"urn:ietf:params:xml:ns:plasma:obligation:signature-required".
A S/MIME Capabilities data value can optionally be included. If
it is included, then it contains the set of S/MIME capabilities
that describes the set of signature algorithms from which the
signature algorithm for the message MUST be selected.
10.2.2. Content Encryption Algorithm Required
Occasionally a policy requires a specific set of encryption
algorithms be used for a message, when this is the case then the
encryption required obligation is included in the returned set of
obligations. If the default set of encryption algorithms is
sufficient then the obligation is omitted.
When used as an Obligation:
The ObligationId attribute is
"urn:ietf:params:xml:schema:plasma:1.0:obligation:content-
encryption".
An S/MIME Capabilities data value MUST be included containing the
set of permitted encryption algorithms. The algorithms included
MUST include a sufficient set of algorithms for the message to be
encrypted. An absolute minimum would be a content encryption
algorithm and key encryption algorithm.
10.2.3. Lock Box Required
This obligation will be used in one of two situations:
1. The policy requires that the plain content encryption key not be
given to the Plasma server, but instead the Plasma client is
required to locate the appropriate certificates and create lock
boxes for each of the message recipients. In this situation, the
Plasma server would never have any access to the content
Schaad Expires August 18, 2014 [Page 45]
Internet-Draft EPS TRUST February 2014
encryption key and thus would be unable to provide the key to any
entity. The Plasma server in this case is responsible only for
the enforcement of the policy enforcement on the message access.
2. The policy requires that the content encryption key not be given
to the Plasma server as a base64 encoded blob, but instead the
Plasma client is required to use the provided certificate to
create a lock box for the Plasma server. In this situation, the
Plasma server does have access to the content encryption key and
thus has the ability to do late binding. The Plasma server is
also still responsible for the enforcement of the policy on
message access.
When used as an Obligation:
The ObligationId attribute is
"urn:ietf:params:xml:schema:plasma:1.0:obligation:lockbox-
required".
There is no data value when the client is required to create lock
boxes for every recipient, i.e. early binding.
The data value is an X509 certificate when the Plasma client is
required to create a lock box for the Plasma server. The
certificate provided MUST have the Plasma CEK Transport EKU
specified.
11. Certificate Profiles
We need to put in text to express the following items:
DNS or IPAddr subject alt name to be present
Have one of four EKUs
Plasma Token EKU - Signals that it can sign and/or encrypt a
plasma object
Plasma Secure Session - Use for the TLS session
Plasma CEK Transport - Used for transporting the CEK to the
server in high security situations
MUST NOT have the anyPolicy EKU set
Schaad Expires August 18, 2014 [Page 46]
Internet-Draft EPS TRUST February 2014
12. Message Transmission
Plasma messages are sent over a TCP connection using port TBD1 on the
server. The client first setups up TLS on the connection, then sends
the UTF8 encoded XML message over the TLS connection as an atomic
message. The XML MUST be encoded as UTF8, however the Byte Order
Mark (BOM) is sent. The response comes back on the same connection.
The client is responsible for closing the TLS session and the TCP
connection when either no more messages are to be sent to the server
or a final indeterminate state has been reached.
If a Plasma server receives an XML request which is not well formed
XML, the server if free to close the connection without first sending
an error reply.
The Plasma server SHOULD support TLS resumption [RFC5077].
Plasma clients and server MUST support TLS 1.1 [RFC4346] and above.
Implementations SHOULD NOT allow for the use of TLS 1.0 or SSL.
13. Plasma URI Scheme
13.1. Plasma URI Schema Syntax
The scheme name for is "plasma".
The syntax for the plasma URI Schema is:
URI = "plasma" ":" "//" authority path-empty
Using the ABNF defined in [RFC3986]. When the port component is
absent, then the value of TBD1 will be used. The userinfo portion of
the authority MUST be absent.
13.2. Definition of Operations
This schema is defined to provide the location of a Plasma server.
The sole operation is to establish a connection to the Plasma server
over which the protocol defined in this document is to run.
14. Security Considerations
To be supplied after we have a better idea of what the document looks
like.
Schaad Expires August 18, 2014 [Page 47]
Internet-Draft EPS TRUST February 2014
14.1. Plasma URI Schema Considerations
TBD
15. IANA Considerations
We define the following name spaces
New name space for the plasma documents urn:ietf:params:xml:ns:plasma
15.1. Plasma Action Values
A new registry is established for Plasma server action identifiers
using the tag "actions". The full urn for the registry is
"urn:ietf:params:xml:ns:plasma:actions". This registry operates
under a specification required policy. All entries in this registry
require the following elements:
o A string in camel case which identifies the action to be
performed.
o An optional XML data structure used to carry the control data for
the action.
o An optional XML data structure used to return the result of the
action from the server.
o A document reference describing the steps to be taken by the
server.
The registry will be initially populated with the following:
+-----------------+-----------------+------------------+
| Action Id | Input Structure | Output Structure |
+-----------------+-----------------+------------------+
| GetRoleTokens | none | eps:RoleToken |
| | | |
| GetSendCMSToken | eps:GetCMSToken | eps:CMSLockBox |
| | | |
| ParseCMSToken | eps:CMSLockBox | eps:CMSKey |
| | | |
| GetReplyToken | none | eps:RoleToken |
+-----------------+-----------------+------------------+
When these actions are placed in an xacml:Request,
o the Category is "urn:oasis:names:tc:xacml:3.0:attribute-
category:action",
Schaad Expires August 18, 2014 [Page 48]
Internet-Draft EPS TRUST February 2014
o the AttributeId is "urn:ietf:params:xml:ns:plasma:actions",
o the DataType is "http://www.w3.org/2001/XMLSchema#string"
15.2. non
Define a new data name space urn:ietf:params:xml:ns:plasma:data
CMSToken
ChannelBinding
SMIME-Capabilities
Define a new name space for status codes at
urn:ietf:params:xml:ns:plasma:status. The initial set of values is
authentication-error This identifier indicates that the
authentication methods failed to successfully complete.
Define a new name space for obligations. The same namespace will be
used both for obligations and for advice and the values may appear in
either section.
signature-required This identifier indicates that that the encrypted
body must contain a signature element. The data value of this
type shall be "http://www.w3.org/2001/XMLSchema#hexBinary" and the
data structure shall consist of a DER encoded CMSCapabilities
structure [RFC5751] with the list of permitted signature
algorithms. If there are no restrictions on the algorithms or the
restriction is implicit, then the data value MAY be omitted.
encryption-algorithms see above
ambigous-identity The identity of the client is either not stated in
a form the Plasma server understands, or there are multiple
identities in the authentication data. To remedy this situation,
the client includes an explicit identity in the xacml:Reqeust
element.
We define a schema in appendix A at
urn:ietf:params:xml:schema:plasma:1.0:RFCTBD
Define a new Status Code for use in the Status URI field.
urn:ietf:params:xml:ns:plasma:status:gss-api-response - This
status is returned only with Indefinite responses. Indicates a
Schaad Expires August 18, 2014 [Page 49]
Internet-Draft EPS TRUST February 2014
GSS-API response object was returned in the GSSAPIResponse token
type. Will return until authentication has been completed.
15.3. Port Assignment
We request that IANA assign a new port for the use of this protocol.
Service name: plasma
Port Number: TBD1
Transport Protocol: TCP
Description: Plasma Service Protocol
Reference: This document
Assignee: iesg@ietf.org
Contact: chair@ietf.org
Notes: The protocol requires that TLS be used to communicate over
this port. There is no provision for unsecure messages to be sent to
this protocol.
16. Open Issues
List of Open Issues:
o JLS: Should we require that any SignatureProperty be present for
XML Signature elements?
o JLS: Need to figure out an appropriate way to reference the
assertion from a dig sig element. Could use a special version of
RetrievalMethod with a transform, but that does not seem correct.
May need to define a new KeyInfo structure to do it.
o JLS: Should X.509 certificates and attribute certificates be fully
specified as an authentication method?
o JLS: Should a SignerInfo attribute be placed under the access-
subject Category for a senders version and under Environment for a
machine version? Currently both are under Data
o JLS: Need an obligation to say that CEK must be encrypted. Do we
also need to have recipient info structures encrypted?
Schaad Expires August 18, 2014 [Page 50]
Internet-Draft EPS TRUST February 2014
17. References
17.1. Normative References
[ABFAB] Hartman, S. and J. Howlett, "A GSS-API Mechanism for the
Extensible Authentication Protocol", Work In Progress
draft-ietf-abfab-gss-eap-04, Oct 2011.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[I-D.schaad-plasma-cms]
Schaad, J., "Email Policy Service ASN.1 Processing", Work
In Progress draft-schaad-plamsa-cms, Jan 2011.
[XML-Signature]
Roessler, T., Reagle, J., Hirsch, F., Eastlake, D., and D.
Solo, "XML Signature Syntax and Processing (Second
Edition)", World Wide Web Consortium Recommendation REC-
xmldsig-core-20080610, June 2008,
<http://www.w3.org/TR/2008/REC-xmldsig-core-20080610>.
[XML-C14N11]
Boyer, J. and G. Marcy, "Canonical XML Version 1.1", World
Wide Web Consortium Recommendation REC-xml-
c14n11-20080502, May 2008,
<http://www.w3.org/TR/2008/REC-xml-c14n11-20080502>.
[WS-TRUST]
Lawrence, K., Kaler, C., Nadalin, A., Goodner, M., Gudgin,
M., Barbir, A., and H. Granqvist, "WS-Trust 1.4", OASIS
Standard ws-trust-200902, March 2007,
<http://docs.oasis-open.org/ws-sx/ws-trust/v1.4/
ws-trust.html>.
[XACML] Rissanen, E., Ed., "eXtensible Access Control Markup
Language (XACML) Version 3.0", OASIS Standard
xacml-201008, August 2010, <http://docs.oasis-open.org/
xacml/3.0/xacml-3.0-core-spec-cs-01.en.doc>.
[I-D.freeman-plasma-requirements]
Freeman, T., Schaad, J., and P. Patterson, "Requirements
for Message Access Control", Work in progress draft-
freeman-message-access-control, October 2011.
Schaad Expires August 18, 2014 [Page 51]
Internet-Draft EPS TRUST February 2014
[OASIS-CORE]
Cantor, S., Ed., Kemp, J., Ed., Philpott, R., Ed., and E.
Maler, Ed., "Assertions and Protocols for the OASIS
Security Assertion Markup Language (SAML) V2.0", OASIS
Standard saml-core-2.0-os, March 2005.
[RFC5705] Rescorla, E., "Keying Material Exporters for Transport
Layer Security (TLS)", RFC 5705, March 2010.
[RFC5751] Ramsdell, B. and S. Turner, "Secure/Multipurpose Internet
Mail Extensions (S/MIME) Version 3.2 Message
Specification", RFC 5751, January 2010.
[RFC7055] Hartman, S. and J. Howlett, "A GSS-API Mechanism for the
Extensible Authentication Protocol", RFC 7055, December
2013.
17.2. Informative References
[RFC5554] Williams, N., "Clarifications and Extensions to the
Generic Security Service Application Program Interface
(GSS-API) for the Use of Channel Bindings", RFC 5554, May
2009.
[RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[RFC4998] Gondrom, T., Brandner, R., and U. Pordesch, "Evidence
Record Syntax (ERS)", RFC 4998, August 2007.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, January 2008.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC
3986, January 2005.
[SAML-XACML]
Anderson, A., Ed. and H. Lockhart, Ed., "SAML 2.0 profile
of XACML v2.0", OASIS Standard access_control-xacml-2.0
-saml-profile-spec-os.pdf, February 2005.
[PlasmaBasicPolicy]
Anon, A., "IETF Defined Plasma Policies", February 2005.
Schaad Expires August 18, 2014 [Page 52]
Internet-Draft EPS TRUST February 2014
[SOAP11] Box, D., Ehnebuske, D., Kakivaya, G., Layman, A.,
Mendelsohn, N., Nielsen, H., Thatte, S., and D. Winer,
"Simple Object Access Protocol (SOAP) 1.1", W3C NOTE NOTE-
SOAP-20000508, May 2000.
[SOAP12] Lafon, Y., Gudgin, M., Hadley, M., Moreau, J., Mendelsohn,
N., Karmarkar, A., and H. Nielsen, "SOAP Version 1.2 Part
1: Messaging Framework (Second Edition)", World Wide Web
Consortium Recommendation REC-soap12-part1-20070427, April
2007,
<http://www.w3.org/TR/2007/REC-soap12-part1-20070427>.
[I-D.ietf-emu-eap-tunnel-method]
Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
"Tunnel EAP Method (TEAP) Version 1", draft-ietf-emu-eap-
tunnel-method-09 (work in progress), September 2013.
[RFC7029] Hartman, S., Wasserman, M., and D. Zhang, "Extensible
Authentication Protocol (EAP) Mutual Cryptographic
Binding", RFC 7029, October 2013.
[RFC5891] Klensin, J., "Internationalized Domain Names in
Applications (IDNA): Protocol", RFC 5891, August 2010.
[W3C.WD-xmlenc-core1-20101130]
Roessler, T., Reagle, J., Hirsch, F., and D. Eastlake,
"XML Encryption Syntax and Processing Version 1.1", World
Wide Web Consortium LastCall WD-xmlenc-core1-20101130,
November 2010,
<http://www.w3.org/TR/2010/WD-xmlenc-core1-20101130>.
Appendix A. XML Schema
This appendix represents the entirety of the XML Schema for Plasma
documents.
<?xml version="1.0" encoding="UTF-8"?>
<!-- edited with XMLSpy v2007 rel. 3 sp1 (http://www.altova.com) by James Schaad (exmsft) -->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17" xmlns:wst="http://schemas.xmlsoap.org/ws/2005/02/trust" xmlns:eps="urn:ietf:params:ns:plasma:1.0" xmlns:ds2="http://www.w3.org/2000/09/xmldsig#" xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion" xmlns:xenc="http://www.w3.org/2001/04/xmlenc#" targetNamespace="urn:ietf:params:ns:plasma:1.0" elementFormDefault="qualified" attributeFormDefault="unqualified">
<xs:annotation>
<xs:documentation>
The PlasmaRequest element is one of two top level elements defined by this XSD schema.
The PlasmaRequest element is sent from the client to the server in order to
</xs:documentation>
</xs:annotation>
<xs:element name="PlasmaRequest" type="eps:RequestType"/>
<xs:complexType name="RequestType">
<xs:sequence>
Schaad Expires August 18, 2014 [Page 53]
Internet-Draft EPS TRUST February 2014
<xs:element ref="eps:Authentication" minOccurs="0"/>
<xs:element ref="xacml:Request"/>
</xs:sequence>
<xs:attribute name="Version" type="xs:string" default="1.0"/>
</xs:complexType>
<xs:element name="PlasmaResponse" type="eps:ResponseType"/>
<xs:complexType name="ResponseType">
<xs:sequence>
<xs:element ref="xacml:Response"/>
<xs:element ref="eps:PlasmaReturnToken" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="Version" type="xs:string" default="1.0"/>
</xs:complexType>
<xs:element name="PlasmaReturnToken" type="eps:PlasmaReturnTokenType"/>
<xs:complexType name="PlasmaReturnTokenType">
<xs:sequence>
<xs:any namespace="##any" processContents="lax"/>
</xs:sequence>
<xs:attribute name="DecisionId" type="xs:string"/>
</xs:complexType>
<xs:element name="Authentication" type="eps:AuthenticationType"/>
<xs:complexType name="AuthenticationType">
<xs:choice maxOccurs="unbounded">
<xs:element ref="saml:Assertion"/>
<xs:element name="GSSAPI" type="xs:hexBinary"/>
<xs:element name="RoleToken">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##any" processContents="lax"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element ref="ds2:Signature"/>
<xs:element name="Other">
<xs:complexType>
<xs:sequence>
<xs:any namespace="##other"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
<xs:element name="RoleToken" type="eps:RoleTokenType"/>
<xs:complexType name="RoleTokenType">
<xs:sequence>
<xs:element name="FriendlyName" type="xs:string"/>
<xs:element name="PDP" type="xs:anyURI" maxOccurs="unbounded"/>
<xs:choice>
Schaad Expires August 18, 2014 [Page 54]
Internet-Draft EPS TRUST February 2014
<xs:element name="PolicyList">
<xs:complexType>
<xs:sequence>
<xs:element name="Policy" type="eps:PolicyDescType" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
<xs:element ref="wst:RequestSecurityTokenResponse"/>
<xs:element ref="xacml:Obligations" minOccurs="0"/>
<xs:element ref="xacml:AssociatedAdvice" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:complexType name="PolicyDescType">
<xs:sequence>
<xs:element name="FriendlyName" type="xs:string"/>
<xs:element name="Options" minOccurs="0">
<xs:complexType>
<xs:complexContent>
<xs:extension base="xs:anyType">
<xs:attribute name="optionsType" type="xs:anyURI" use="required"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:attribute name="PolicyId" type="xs:anyURI" use="required"/>
</xs:complexType>
<xs:element name="PolicySet" type="eps:PolicySetType"/>
<xs:complexType name="PolicySetType">
<xs:sequence>
<xs:choice maxOccurs="unbounded">
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
</xs:sequence>
<xs:attribute name="PolicyCombiningAlgId" type="xs:anyURI" use="required"/>
</xs:complexType>
<xs:element name="Policy" type="eps:PolicyType"/>
<xs:complexType name="PolicyType">
<xs:sequence>
<xs:any namespace="##any" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="PolicyId" type="xs:anyURI" use="required"/>
</xs:complexType>
<xs:element name="GetCMSToken" type="eps:CMSTokenRequestType"/>
Schaad Expires August 18, 2014 [Page 55]
Internet-Draft EPS TRUST February 2014
<xs:complexType name="CMSTokenRequestType">
<xs:sequence>
<xs:choice>
<xs:element ref="eps:Policy"/>
<xs:element ref="eps:PolicySet"/>
</xs:choice>
<xs:element name="Hash">
<xs:complexType>
<xs:sequence>
<xs:element ref="ds2:DigestMethod"/>
<xs:element ref="ds2:DigestValue" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
</xs:element>
<xs:element name="LockBox" type="eps:LockBoxType" minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="CEK" type="xs:hexBinary" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="LockBox" type="eps:LockBoxType"/>
<xs:complexType name="LockBoxType">
<xs:sequence>
<xs:element name="Subject" maxOccurs="unbounded">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:anySimpleType">
<xs:attribute name="type" type="xs:string" use="required"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
<xs:choice>
<xs:element name="CMSLockBox" type="xs:base64Binary"/>
<xs:element name="XMLLockBox" type="xenc:EncryptedKeyType"/>
<xs:any namespace="##other" processContents="lax"/>
</xs:choice>
</xs:sequence>
</xs:complexType>
<xs:element name="CMSKey" type="eps:CMSKeyResponseType"/>
<xs:complexType name="CMSKeyResponseType">
<xs:sequence>
<xs:element name="DisplayString" type="xs:string"/>
<xs:choice>
<xs:element name="CEK" type="xs:base64Binary"/>
<xs:element name="CMSLockBox" type="xs:base64Binary"/>
<xs:element name="XMLLockBox" type="enc:EncryptedKeyType"/>
<xs:any namespace="##other" processContents="lax"/>
</xs:choice>
<xs:element ref="eps:RoleToken" minOccurs="0"/>
Schaad Expires August 18, 2014 [Page 56]
Internet-Draft EPS TRUST February 2014
<xs:element ref="xacml:Attributes" minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
<xs:element name="CMSToken" type="eps:CMSTokenResponseType"/>
<xs:complexType name="CMSTokenResponseType">
<xs:sequence>
<xs:element name="CMSLockBox" maxOccurs="unbounded">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:base64Binary">
<xs:attribute name="CMSType" type="xs:string"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:complexType name="LockboxKey">
<xs:sequence>
<xs:choice>
<xs:element name="X509Certificate" type="xs:base64Binary"/>
<xs:element name="PGPKey" type="xs:base64Binary"/>
<xs:element ref="ds2:KeyInfo"/>
</xs:choice>
<xs:element name="Capabilities" type="xs:base64Binary" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
<xs:element name="XMLToken" type="eps:XMLTokenResponseType"/>
<xs:complexType name="XMLTokenResponseType">
<xs:sequence>
<xs:element name="XMLLockBox" maxOccurs="unbounded" type="xenc:EncryptedKeyType"/>
</xs:sequence>
</xs:complexType>
</xs:schema>
Appendix B. Example: Get Roles Request
This section provides an example of a request message to obtain the
set of roles for an individual named 'bart@simpsons.com'. The
authentication provided in this is a SAML statement included in the
SAML_Collection element.
Schaad Expires August 18, 2014 [Page 57]
Internet-Draft EPS TRUST February 2014
<?xml version="1.0" encoding="UTF-8"?>
<PlasmaRequest xmlns="urn:ietf:schema:plasma:1.0"
xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17"
xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="urn:ietf:schema:plasma:1.0 C:\ietf\drafts\Schema\Plasma.xsd" >
<Authentication>
<WS-Token>123456</WS-Token>
<!-- <saml:Assertion>....</saml:Assertion> -->
</Authentication>
<xacml:Request CombinedDecision="false" ReturnPolicyIdList="false">
<xacml:Attributes Category="urn:oasis:names:tc:xaml:3.0:attribute-catagory:action">
<xacml:Attribute IncludeInResult="false" AttributeId="urn:plasma:action-id">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">GetRoleTokens</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment">
<xacml:Attribute AttributeId="urn:ietf:plasma:data:channel" IncludeInResult="false">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#base64Binary">ABCDEFGH</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
</xacml:Request>
</PlasmaRequest>
Appendix C. Example: Get Roles Response
This section provides an example response to a successful request for
a role sets.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<eps:PlasmaResponse xmlns:eps="urn:ietf:params:ns:plasma:1.0">
<xacml:Response xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:PlasmaReturnToken>
<eps:RoleToken>
<eps:FriendlyName>Role #1</eps:FriendlyName>
<eps:PDP>plasma://localhost:8080</eps:PDP>
<eps:PolicyList>
<eps:Policy PolicyId="urn:example:PlasmaPolicies:Policy1">
<eps:FriendlyName>Schaad Policy 1</eps:FriendlyName>
</eps:Policy>
</eps:PolicyList>
<wst:RequestSecurityTokenResponse xmlns:wst="http://schemas.xmlsoap.org/ws/2005/02/trust">
<wst:RequestedSecurityToken>
<ex:MyToken xmlns:ex="http://example.com/SecurityToken">MCgMCzxDb250ZXh0IC8+AgEBMBYYFDEvMTAvMjAxMyA0OjIyOjAwIEFN</ex:MyToken>
Schaad Expires August 18, 2014 [Page 58]
Internet-Draft EPS TRUST February 2014
</wst:RequestedSecurityToken>
<wst:Lifetime>
<wsu:Expires xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">2013-01-10T04:22:00</wsu:Expires>
</wst:Lifetime>
</wst:RequestSecurityTokenResponse>
<Obligations xmlns="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<Obligation ObligationId="Obligation-Fred" />
</Obligations>
</eps:RoleToken>
</eps:PlasmaReturnToken>
<eps:PlasmaReturnToken>
<eps:RoleToken>
<eps:FriendlyName>Plasma Basic Policy</eps:FriendlyName>
<eps:PDP>plasma://localhost:8080</eps:PDP>
<eps:PolicyList>
<eps:Policy PolicyId="urn:ietf:ns:plasma:policy:basic">
<eps:FriendlyName>Plasma Basic Policy</eps:FriendlyName>
</eps:Policy>
<eps:Policy PolicyId="urn:example:PlasmaPolicies:Policy1">
<eps:FriendlyName>Schaad Policy 1</eps:FriendlyName>
</eps:Policy>
</eps:PolicyList>
<wst:RequestSecurityTokenResponse xmlns:wst="http://schemas.xmlsoap.org/ws/2005/02/trust">
<wst:RequestedSecurityToken>
<ex:MyToken xmlns:ex="http://example.com/SecurityToken">MCgMCzxDb250ZXh0IC8+AgEBMBYYFDEvMTAvMjAxMyA0OjIyOjAwIEFN</ex:MyToken>
</wst:RequestedSecurityToken>
<wst:Lifetime>
<wsu:Expires xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">2013-01-10T04:22:00</wsu:Expires>
</wst:Lifetime>
</wst:RequestSecurityTokenResponse>
</eps:RoleToken>
</eps:PlasmaReturnToken>
</eps:PlasmaResponse>
In this example a role is returned that has two different policies
that can be used by that role. Along with the role token, a binary
secret is returned that is to be used in proving that the same entity
is returning to use the roles.
Appendix D. Example: Get CMS Token Request
This section contains an example of a request from a client to a
server for a CMS message token to be issued. The authentication for
the request is provided by using a WS-Trust token previously issued
as part of a role request/response dialog. The request contains the
following elements:
Schaad Expires August 18, 2014 [Page 59]
Internet-Draft EPS TRUST February 2014
o A complex rule set is requested where permission to is to be
granted to anyone who meets either of the two policies given.
o A specific recipient info structure is provided for a subject
who's name is 'lisa@simpsons.com'. The details of the recipient
info structure are skipped but it would be any encoding of a
RecipientInfo structure from CMS.
o A generic key encryption key is provided for any other subject who
meets the policies specified.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<eps:PlasmaRequest xmlns:eps="urn:ietf:params:ns:plasma:1.0">
<eps:Authentication>
<eps:RoleToken>
<ex:MyToken xmlns:ex="http://example.com/SecurityToken">MCgMCzxDb250ZXh0IC8+AgEBMBYYFDEvMTAvMjAxMyAxOjI3OjEyIEFN</ex:MyToken>
</eps:RoleToken>
</eps:Authentication>
<xacml:Request CombinedDecision="false" ReturnPolicyIdList="false" id="XACMLRequest" xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<xacml:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:params:actions" IncludeInResult="false">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">GetCMSToken</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:plasma:data:channel" IncludeInResult="false">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#base64Binary">tls-unique</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="urn:ietf:params:xml:ns:params:data">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:params:data:CMSTokenRequest" IncludeInResult="false">
<xacml:AttributeValue DataType="urn:ietf:params:ns:plasma:1.0#CMSTokenRequestType">
<eps:GetCMSToken>
<eps:PolicySet PolicyCombiningAlgId="urn:oasis:names:tc:xacml:3.0:policy-combining-algorithm:permit-overrides">
<eps:Policy PolicyId="urn:example:PlasmaPolicies:Policy1" />
</eps:PolicySet>
<eps:Hash>
<ds2:DigestMethod Algorithm="http://www.w3.org/2001/04/xmlenc#sha256" xmlns:ds2="http://www.w3.org/2000/09/xmldsig#" />
<ds2:DigestValue xmlns:ds2="http://www.w3.org/2000/09/xmldsig#">AQIDBAUGBwgJCg==</ds2:DigestValue>
</eps:Hash>
<eps:CEK>0102030405060708090A</eps:CEK>
</eps:GetCMSToken>
</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
</xacml:Request>
</eps:PlasmaRequest>
Schaad Expires August 18, 2014 [Page 60]
Internet-Draft EPS TRUST February 2014
Appendix E. Example: Get CMS Token Response
This section contains an example of a response from a server to a
client for a CMS message token to be issued. The token is returned
in the CMSToken element. This element would then be placed into the
CMS message being created by the client.
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<eps:PlasmaResponse xmlns:eps="urn:ietf:params:ns:plasma:1.0">
<xacml:Response xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:PlasmaReturnToken>
<eps:CMSLockbox>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</eps:CMSLockbox>
</eps:PlasmaReturnToken>
</eps:PlasmaResponse>
Appendix F. Example: Get CMS Key Request
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<eps:PlasmaRequest xmlns:eps="urn:ietf:params:ns:plasma:1.0">
<eps:Authentication>
<eps:RoleToken>
<ex:MyToken xmlns:ex="http://example.com/SecurityToken">MCgMCzxDb250ZXh0IC8+AgEBMBYYFDEvMTAvMjAxMyAxOjI3OjEyIEFN</ex:MyToken>
</eps:RoleToken>
</eps:Authentication>
<xacml:Request CombinedDecision="false" ReturnPolicyIdList="false" xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<xacml:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:params:actions" IncludeInResult="false">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">GetCMSKey</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:plasma:data:channel" IncludeInResult="false">
<xacml:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#base64Binary">tls-unique</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
<xacml:Attributes Category="urn:ietf:params:xml:ns:params:data">
<xacml:Attribute AttributeId="urn:ietf:params:xml:ns:params:data:CMSKeyRequest" IncludeInResult="false">
<xacml:AttributeValue DataType="urn:ietf:params:ns:plasma:1.0#CMSLockbox">
<eps:CMSLockbox>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</eps:CMSLockbox>
</xacml:AttributeValue>
</xacml:Attribute>
</xacml:Attributes>
</xacml:Request>
</eps:PlasmaRequest>
Schaad Expires August 18, 2014 [Page 61]
Internet-Draft EPS TRUST February 2014
Appendix G. Example: Get CMS KeyResponse
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<eps:PlasmaResponse xmlns:eps="urn:ietf:params:ns:plasma:1.0">
<xacml:Response xmlns:xacml="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
<xacml:Result>
<xacml:Decision>Permit</xacml:Decision>
</xacml:Result>
</xacml:Response>
<eps:PlasmaReturnToken>
<CMSKey:eps xmlns:CMSKey="urn:ietf:params:ns:plasma:1.0">
<eps:DisplayString>Schaad Policy 1</eps:DisplayString>
<eps:CEK>AQIDBAUGBwgJCg==</eps:CEK>
</CMSKey:eps>
</eps:PlasmaReturnToken>
</eps:PlasmaResponse>
Appendix H. Enabling the MultiRequests option
NOTE: RFC Editor please remove this section prior to publication.
This section exists as a note to the author to make sure that it can
be done. It will be published as a separate document if desired.
One of the issues in doing multiple requests in a single message is
the issue of correlation between the request and the results. We
have make this issue even worse by the fact that we are return
results that are not input attributes for the decision and that we
are not returning as attributes of the decision.
The best way to deal with this is by putting tags into the request
and reflect them in the return values for the response. The only
place that this does not work is for the GSS-API response token as
this element would normally be part of the response of multiple
requests. You want to finish that authentication step before issuing
final decisions if the input is needed as part of that decision.
With this in mind what we do is the following:
o Define a new data attribute for plasma as plasma-request-id. The
category for it is urn:ietf:params:xml:ns:plasma:data. The type
will be a string.
o When the new attribute is used, then the return attribute flag
MUST be set on the attribute.
o There MUST be one entity of the new attribute, with a unique
value, for each of the requests in the MultiRequest element.
Schaad Expires August 18, 2014 [Page 62]
Internet-Draft EPS TRUST February 2014
o Exactly one of the new attributes MUST be referenced in each
request in the MultiRequest element.
o The server copies the value of the attribute into the ***
attribute of the returned token.
We could probably relax the restrictions if we know that the token
can only be returned by one request, however using the token to
correlate the request and the decision is still probably desired so
that those values can be correlated.
Author's Address
Jim Schaad
Soaring Hawk Consulting
Email: ietf@augustcellars.com
Schaad Expires August 18, 2014 [Page 63]
