Internet DRAFT - draft-gerdes-ace-dtls-authorize
draft-gerdes-ace-dtls-authorize
ACE Working Group S. Gerdes
Internet-Draft O. Bergmann
Intended status: Standards Track C. Bormann
Expires: September 14, 2017 Universitaet Bremen TZI
G. Selander
Ericsson
L. Seitz
RISE SICS
March 13, 2017
Datagram Transport Layer Security (DTLS) Profile for Authentication and
Authorization for Constrained Environments (ACE)
draft-gerdes-ace-dtls-authorize-01
Abstract
This specification defines a profile for delegating client
authentication and authorization in a constrained environment by
establishing a Datagram Transport Layer Security (DTLS) channel
between resource-constrained nodes. The protocol relies on DTLS for
communication security between entities in a constrained network. A
resource-constrained node can use this protocol to delegate
management of authorization information to a trusted host with less
severe limitations regarding processing power and memory.
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
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This Internet-Draft will expire on September 14, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Unauthorized Resource Request Message . . . . . . . . . . 5
2.2. AS Information . . . . . . . . . . . . . . . . . . . . . 6
2.3. Resource Access . . . . . . . . . . . . . . . . . . . . . 7
2.4. Dynamic Update of Authorization Information . . . . . . . 8
3. RawPublicKey Mode . . . . . . . . . . . . . . . . . . . . . . 9
4. PreSharedKey Mode . . . . . . . . . . . . . . . . . . . . . . 10
4.1. DTLS Channel Setup Between C and RS . . . . . . . . . . . 11
4.2. Updating Authorization Information . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 14
5.1. Unprotected AS Information . . . . . . . . . . . . . . . 14
5.2. Use of Nonces for Replay Protection . . . . . . . . . . . 14
5.3. Privacy . . . . . . . . . . . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . 15
7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
This specification defines a profile of the ACE framework
[I-D.ietf-ace-oauth-authz]. In this profile, a client and a resource
server use CoAP [RFC7252] over DTLS [RFC6347] to communicate. The
client uses an access token, bound to a key (the proof-of-possession
key) to authorize its access to the resource server. DTLS provides
communication security, proof of possession, and server
authentication. Optionally the client and the resource server may
also use CoAP over DTLS to communicate with the authorization server.
This specification supports the DTLS PSK handshake [RFC4279] and the
DTLS handshake with Raw Public Keys (RPK) [RFC7250].
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The DTLS PSK handshake [RFC4279] provides the proof-of-possession for
the key tied to the access token. Furthermore the psk_identity
parameter in the DTLS PSK handshake is used to transfer the access
token from the client to the resource server.
The DTLS RPK handshake [RFC7250] requires client authentication to
provide proof-of-possession for the key tied to the access token.
Here the access token needs to be transferred to the resource server
before the handshake is initiated, as described in section 8.1 of
draft-ietf-ace-oauth-authz. [1]
Note: While the scope of this draft is on client and resource server
communicating using CoAP over DTLS, it is expected that it applies
also to CoAP over TLS, possibly with minor modifications.
However, that is out of scope for this version of the draft.
1.1. 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 RFC 2119 [RFC2119].
Readers are expected to be familiar with the terms and concepts
described in [I-D.ietf-ace-oauth-authz].
2. Protocol Overview
The CoAP-DTLS profile for ACE specifies the transfer of
authentication and, if necessary, authorization information between C
and RS during setup of a DTLS session for CoAP messaging. It also
specifies how a Client can use CoAP over DTLS to retrieve an Access
Token from AS for a protected resource hosted on RS.
This profile requires a Client (C) to retrieve an Access Token for
the resource(s) it wants to access on a Resource Server (RS) as
specified in [I-D.ietf-ace-oauth-authz]. Figure 1 shows the typical
message flow in this scenario (messages in square brackets are
optional):
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C RS AS
| [-- Resource Request --->] | |
| | |
| [<----- AS Information --] | |
| | |
| --- Token Request ----------------------------> |
| | |
| <---------------------------- Access Token ----- |
| + RS Information |
Figure 1: Retrieving an Access Token
To determine the AS in charge of a resource hosted at the RS, C MAY
send an initial Unauthorized Resource Request message to RS. RS then
denies the request and sends the address of its AS back to C.
Instead of the initial Unauthorized Resource Request message, C MAY
look up the desired resource in a resource directory (cf.
[I-D.ietf-core-resource-directory]).
Once C knows AS's address, it can send an Access Token request to the
/token endpoint at the AS as specified in [I-D.ietf-ace-oauth-authz].
If C wants to use the CoAP RawPublicKey mode as described in
Section 9 of RFC 7252 [2] it MUST provide a key or key identifier
within a "cnf" object in the token request. If AS decides that the
request is to be authorized it generates an access token response for
C containing a "profile" parameter with the value "coap_dtls" to
indicate that this profile MUST be used for communication between C
and RS. Is also adds a "cnf" parameter with additional data for the
establishment of a secure DTLS channel between C and RS. The
semantics of the 'cnf' parameter depend on the type of key used
between C and RS, see Section 3 and Section 4.
The Access Token returned by AS then can be used by C to establish a
new DTLS session with RS. When C intends to use asymmetric
cryptography in the DTLS handshake with RS, C MUST upload the Access
Token to the "/authz-info" resource on RS before starting the DTLS
handshake, as described in section 8.1 of draft-ietf-ace-oauth-authz
[3]. If only symmetric cryptography is used between C and RS, the
Access Token MAY instead be transferred in the DTLS ClientKeyExchange
message (see Section 4.1).
Figure 2 depicts the common protocol flow for the DTLS profile after
C has retrieved the Access Token from AS.
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C RS AS
| [--- Access Token ------>] | |
| | |
| <== DTLS channel setup ==> | |
| | |
| == Authorized Request ===> | |
| | |
| <=== Protected Resource == | |
Figure 2: Protocol overview
The following sections specify how CoAP is used to interchange
access-related data between RS and AS so that AS can provide C and RS
with sufficient information to establish a secure channel, and convey
authorization information specific for this communication
relationship to RS.
Depending on the desired CoAP security mode, the Client-to-AS
request, AS-to-Client response and DTLS session establishment carry
slightly different information. Section 3 addresses the use of raw
public keys while Section 4 defines how pre-shared keys are used in
this profile.
2.1. Unauthorized Resource Request Message
The optional Unauthorized Resource Request message is a request for a
resource hosted by RS for which no proper authorization is granted.
RS MUST treat any CoAP request for a resource other than "/authz-
info" as Unauthorized Resource Request message when any of the
following holds:
o The request has been received on an unprotected channel.
o RS has no valid access token for the sender of the request
regarding the requested action on that resource.
o RS has a valid access token for the sender of the request, but
this does not allow the requested action on the requested
resource.
Note: These conditions ensure that RS can handle requests
autonomously once access was granted and a secure channel has been
established between C and RS. The resource "/authz-info" is publicly
accessible to be able to upload new access tokens to RS (cf.
[I-D.ietf-ace-oauth-authz]).
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Unauthorized Resource Request messages MUST be denied with a client
error response. In this response, the Resource Server SHOULD provide
proper AS Information to enable the Client to request an access token
from RS's Authorization Server as described in Section 2.2.
The response code MUST be 4.01 (Unauthorized) in case the sender of
the Unauthorized Resource Request message is not authenticated, or if
RS has no valid access token for C. If RS has an access token for C
but not for the resource that C has requested, RS MUST reject the
request with a 4.03 (Forbidden). If RS has an access token for C but
it does not cover the action C requested on the resource, RS MUST
reject the request with a 4.05 (Method Not Allowed).
Note: The use of the response codes 4.03 and 4.05 is intended to
prevent infinite loops where a dumb Client optimistically tries to
access a requested resource with any access token received from
AS. As malicious clients could pretend to be C to determine C's
privileges, these detailed response codes must be used only when a
certain level of security is already available which can be
achieved only when the Client is authenticated.
2.2. AS Information
The AS Information is sent by RS as a response to an Unauthorized
Resource Request message (see Section 2.1) to point the sender of the
Unauthorized Resource Request message to RS's AS. The AS information
is a set of attributes containing an absolute URI (see Section 4.3 of
[RFC3986]) that specifies the AS in charge of RS.
TBD: We might not want to add more parameters in the AS information
because
this would not only reveal too much information about RS's
capabilities to unauthorized peers but also be of little value as
C cannot really trust that information anyway.
The message MAY also contain a nonce generated by RS to ensure
freshness in case that the RS and AS do not have synchronized clocks.
Figure 3 shows an example for an AS Information message payload using
CBOR [RFC7049] diagnostic notation.
4.01 Unauthorized
Content-Format: application/ace+cbor
{AS: "coaps://as.example.com/token",
nonce: h'e0a156bb3f'}
Figure 3: AS Information payload example
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In this example, the attribute AS points the receiver of this message
to the URI "coaps://as.example.com/token" to request access
permissions. The originator of the AS Information payload (i.e., RS)
uses a local clock that is loosely synchronized with a time scale
common between RS and AS (e.g., wall clock time). Therefore, it has
included a parameter "nonce" for replay attack prevention (c.f.
Section 5.2).
Note: There is an ongoing discussion how freshness of access tokens
can be achieved in constrained environments. This specification
for now assumes that RS and AS do not have a common understanding
of time that allows RS to achieve its security objectives without
explicitly adding a nonce.
The examples in this document are written in CBOR diagnostic notation
to improve readability. Figure 4 illustrates the binary encoding of
the message payload shown in Figure 3.
a2 # map(2)
00 # unsigned(0) (=AS)
78 1c # text(28)
636f6170733a2f2f61732e657861
6d706c652e636f6d2f746f6b656e # "coaps://as.example.com/token"
05 # unsigned(5) (=nonce)
45 # bytes(5)
e0a156bb3f
Figure 4: AS Information example encoded in CBOR
2.3. Resource Access
Once a DTLS channel has been established as described in Section 3
and Section 4, respectively, C is authorized to access resources
covered by the Access Token it has uploaded to the "/authz-info"
resource hosted by RS.
On the server side (i.e., RS), successful establishment of the DTLS
channel binds C to the access token, functioning as a proof-of-
possession associated key. Any request that RS receives on this
channel MUST be checked against these authorization rules that are
associated with the identity of C. Incoming CoAP requests that are
not authorized with respect to any Access Token that is associated
with C MUST be rejected by RS with 4.01 response as described in
Section 2.1.
Note: The identity of C is determined by the authentication process
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during the DTLS handshake. In the asymmetric case, the public key
will define C's identity, while in the PSK case, C's identity is
defined by the session key generated by AS for this communication.
RS SHOULD treat an incoming CoAP request as authorized if the
following holds:
1. The message was received on a secure channel that has been
established using the procedure defined in this document.
2. The authorization information tied to the sending peer is valid.
3. The request is destined for RS.
4. The resource URI specified in the request is covered by the
authorization information.
5. The request method is an authorized action on the resource with
respect to the authorization information.
Incoming CoAP requests received on a secure DTLS channel MUST be
rejected
1. with response code 4.03 (Forbidden) when the resource URI
specified in the request is not covered by the authorization
information, and
2. with response code 4.05 (Method Not Allowed) when the resource
URI specified in the request covered by the authorization
information but not the requested action.
C cannot always know a priori if a Authorized Resource Request will
succeed. If C repeatedly gets AS Information messages (cf.
Section 2.2) as response to its requests, it SHOULD request a new
Access Token from AS in order to continue communication with RS.
2.4. Dynamic Update of Authorization Information
The Client can update the authorization information stored at RS at
any time. To do so, the Client requests from AS a new Access Token
for the intended action on the respective resource and uploads this
Access Token to the "/authz-info" resource on RS.
Figure 5 depicts the message flow where C requests a new Access Token
after a security association between C and RS has been established
using this protocol.
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C RS AS
| <===== DTLS channel =====> | |
| + Access Token | |
| | |
| --- Token Request ----------------------------> |
| | |
| <---------------------------- New Access Token - |
| + RS Information |
| | |
| --- Update /authz-info --> | |
| New Access Token | |
| | |
| == Authorized Request ===> | |
| | |
| <=== Protected Resource == | |
Figure 5: Overview of Dynamic Update Operation
3. RawPublicKey Mode
To retrieve an access token for the resource that C wants to access,
C requests an Access Token from AS. C MUST add a "cnf" object
carrying either its raw public key or a unique identifier for a
public key that it has previously made known to AS.
An example Access Token request from C to RS is depicted in Figure 6.
POST coaps://as.example.com/token
Content-Format: application/cbor
{
grant_type: client_credentials,
aud: "tempSensor4711",
cnf: {
COSE_Key: {
kty: EC2,
crv: P-256,
x: h'TODOX',
y: h'TODOY'
}
}
}
Figure 6: Access Token Request Example for RPK Mode
The example shows an Access Token request for the resource identified
by the audience string "tempSensor4711" on the AS using a raw public
key.
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When AS authorizes a request, it will return an Access Token and a
"cnf" object in the AS-to-Client response. Before C initiates the
DTLS handshake with RS, it MUST send a "POST" request containing the
new Access Token to the "/authz-info" resource hosted by RS. If this
operation yields a positive response, C SHOULD proceed to establish a
new DTLS channel with RS. To use raw public key mode, C MUST pass
the same public key that was used for constructing the Access Token
with the SubjectPublicKeyInfo structure in the DTLS handshake as
specified in [RFC7250].
Note: According to [RFC7252], CoAP implementations MUST support the
ciphersuite TLS_ECDHE_ECDSA_WITH_AES_128_CCM_8 [RFC7251] and the
NIST P-256 curve. C is therefore expected to offer at least this
ciphersuite to RS.
The Access Token is constructed by AS such that RS can associate the
Access Token with the Client's public key. If CBOR web tokens
[I-D.ietf-ace-cbor-web-token] are used as recommended in
[I-D.ietf-ace-oauth-authz], the AS MUST include a "COSE_Key" object
in the "cnf" claim of the Access Token. This "COSE_Key" object MAY
contain a reference to a key for C that is already known by RS (e.g.,
from previous communication). If the AS has no certain knowledge
that the Client's key is already known to RS, the Client's public key
MUST be included in the Access Token's "cnf" parameter.
4. PreSharedKey Mode
To retrieve an access token for the resource that C wants to access,
C MAY include a "cnf" object carrying an identifier for a symmetric
key in its Access Token request to AS. This identifier can be used
by AS to determine the session key to construct the proof-of-
possession token and therefore MUST specify a symmetric key that was
previously generated by AS as a session key for the communication
between C and RS.
Depending on the requested token type and algorithm in the Access
Token request, AS adds RS Information to the response that provides C
with sufficient information to setup a DTLS channel with RS. For
symmetric proof-of-possession keys (c.f.
[I-D.ietf-ace-oauth-authz]), C must ensure that the Access Token
request is sent over a secure channel that guarantees authentication,
message integrity and confidentiality. This could be, e.g., a DTLS
channel (for "coaps") or an OSCOAP [I-D.ietf-core-object-security]
exchange (for "coap").
When AS authorizes C it returns an AS-to-Client response with the
profile parameter set to "coap_dtls" and a "cnf" parameter carrying a
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"COSE_Key" object that contains the symmetric session key to be used
between C and RS as illustrated in Figure 7.
2.01 Created
Content-Format: application/cbor
Location-Path: /token/asdjbaskd
Max-Age: 86400
{
access_token: b64'SlAV32hkKG ...
(remainder of CWT omitted for brevity;
token_type: pop,
alg: HS256,
expires_in: 86400,
profile: coap_dtls,
cnf: {
COSE_Key: {
kty: symmetric,
k: h'73657373696f6e6b6579'
}
}
}
Figure 7: Example Access Token response
In this example, AS returns a 2.01 response containing a new Access
Token. The information is transferred as a CBOR data structure as
specified in [I-D.ietf-ace-oauth-authz]. The Max-Age option tells
the receiving Client how long this token will be valid.
A response that declines any operation on the requested resource is
constructed according to Section 5.2 of RFC 6749 [4], (cf.
Section 6.3 of [I-D.ietf-ace-oauth-authz]).
4.00 Bad Request
Content-Format: application/cbor
{
error: invalid_request
}
Figure 8: Example Access Token response with reject
4.1. DTLS Channel Setup Between C and RS
When C receives an Access Token from AS, it checks if the payload
contains an "access_token" parameter and a "cnf" parameter. With
this information C can initiate establishment of a new DTLS channel
with RS. To use DTLS with pre-shared keys, C follows the PSK key
exchange algorithm specified in Section 2 of [RFC4279] using the key
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conveyed in the "cnf" parameter of the AS response as PSK when
constructing the premaster secret.
In PreSharedKey mode, the knowledge of the session key by C and RS is
used for mutual authentication between both peers. Therefore, RS
must be able to determine the session key from the Access Token.
Following the general ACE authorization framework, C can upload the
Access Token to RS's "/authz-info" resource before starting the DTLS
handshake. Alternatively, C MAY provide the most recent
base64-encoded Access Token in the "psk_identity" field of the
ClientKeyExchange message.
If RS receives a ClientKeyExchange message that contains a
"psk_identity" with a length greater zero, it MUST base64-decode its
contents and check if the "psk_identity" field contains a key
identifier or Access Token according to the following CDDL
specification:
psk_identity = {
kid => bstr / access_token => bstr
}
The identifiers for the map keys "kid" and "access_token" are used
with the same meaning as in COSE [I-D.ietf-cose-msg] and the ACE
framework [I-D.ietf-ace-oauth-authz] respectively. The identifier
"kid" thus has the value 4 (see [I-D.ietf-cose-msg]), and the
identifier "access_token" has the value 19, respectively (see
[I-D.ietf-ace-oauth-authz]).
If the "psk_identity" field contains a key identifier, the receiver
MUST check if it has one or more Access Tokens that are associated
with the specified key. If no valid Access Token is available for
this key, the DTLS session setup is terminated with an
"illegal_parameter" DTLS alert message.
If instead the "psk_identity" field contains an Access Token, it must
processed in the same way as an Access Token that has been uploaded
to its "/authz-info" resource. In this case, RS continues processing
the ClientKeyExchange message if the contents of the "psk_identity"
contained a valid Access Token. Otherwise, the DTLS session setup is
terminated with an "illegal_parameter" DTLS alert message.
Note1: As RS cannot provide C with a meaningful PSK identity hint in
response to C's ClientHello message, RS SHOULD NOT send a
ServerKeyExchange message.
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Note2: According to [RFC7252], CoAP implementations MUST support the
ciphersuite TLS_PSK_WITH_AES_128_CCM_8 [RFC6655]. C is therefore
expected to offer at least this ciphersuite to RS.
This specification assumes that the Access Token is a PoP token as
described in [I-D.ietf-ace-oauth-authz] unless specifically stated
otherwise. Therefore, the Access Token is bound to a symmetric PoP
key that is used as session key between C and RS.
While C can retrieve the session key from the contents of the "cnf"
parameter in the AS-to-Client response, RS uses the information
contained in the "cnf" claim of the Access Token to determine the
actual session key when no explicit "kid" was provided in the
"psk_identity" field. Usually, this is done by including a
"COSE_Key" object carrying either a key that has been encrypted with
a shared secret between AS and RS, or a key identifier that can be
used by RS to lookup the session key.
Instead of the "COSE_Key" object, AS MAY include a "COSE_Encrypt"
structure to enable RS to calculate the session key from the Access
Token. The "COSE_Encrypt" structure MUST use the _Direct Key with
KDF_ method as described in Section 12.1.2 of draft-ietf-cose-msg
[5]. The AS MUST include a Context information structure carrying a
PartyU "nonce" parameter carrying the nonce that has been used by AS
to construct the session key.
This specification mandates that at least the key derivation
algorithm "HKDF SHA-256" as defined in [I-D.ietf-cose-msg] MUST be
supported. This key derivation function is the default when no "alg"
field is included in the "COSE_Encrypt" structure for RS.
4.2. Updating Authorization Information
Usually, the authorization information that RS keeps for C is updated
by uploading a new Access Token as described in Section 2.4.
If the security association with RS still exists and RS has indicated
support for session renegotiation according to [RFC5746], the new
Access Token MAY be used to renegotiate the existing DTLS session.
In this case, the Access Token is used as "psk_identity" as defined
in Section 4.1. The Client MAY also perform a new DTLS handshake
according to Section 4.1 that replaces the existing DTLS session.
After successful completion of the DTLS handshake RS updates the
existing authorization information for C according to the new Access
Token.
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5. Security Considerations
TODO
5.1. Unprotected AS Information
Initially, no secure channel exists to protect the communication
between C and RS. Thus, C cannot determine if the AS information
contained in an unprotected response from RS to an unauthorized
request (c.f. Section 2.2) is authentic. It is therefore advisable
to provide C with a (possibly hard-coded) list of trustworthy
authorization servers. AS information responses referring to a URI
not listed there would be ignored.
5.2. Use of Nonces for Replay Protection
RS may add a nonce to the AS Information message sent as a response
to an unauthorized request to ensure freshness of an Access Token
subsequently presented to RS. While a timestamp of some granularity
would be sufficient to protect against replay attacks, using
randomized nonce is preferred to prevent disclosure of information
about RS's internal clock characteristics.
5.3. Privacy
An unprotected response to an unauthorized request (c.f.
Section 2.2) may disclose information about RS and/or its existing
relationship with C. It is advisable to include as little
information as possible in an unencrypted response. When a DTLS
session between C and RS already exists, more detailed information
may be included with an error response to provide C with sufficient
information to react on that particular error.
6. IANA Considerations
This document has no actions for IANA.
7. References
7.1. Normative References
[I-D.ietf-ace-oauth-authz]
Seitz, L., Selander, G., Wahlstroem, E., Erdtman, S., and
H. Tschofenig, "Authentication and Authorization for
Constrained Environments (ACE)", draft-ietf-ace-oauth-
authz-05 (work in progress), February 2017.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>.
[RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)",
RFC 4279, DOI 10.17487/RFC4279, December 2005,
<http://www.rfc-editor.org/info/rfc4279>.
[RFC5746] Rescorla, E., Ray, M., Dispensa, S., and N. Oskov,
"Transport Layer Security (TLS) Renegotiation Indication
Extension", RFC 5746, DOI 10.17487/RFC5746, February 2010,
<http://www.rfc-editor.org/info/rfc5746>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<http://www.rfc-editor.org/info/rfc7252>.
7.2. Informative References
[I-D.ietf-ace-cbor-web-token]
Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", draft-ietf-ace-cbor-web-token-03
(work in progress), March 2017.
[I-D.ietf-core-object-security]
Selander, G., Mattsson, J., Palombini, F., and L. Seitz,
"Object Security of CoAP (OSCOAP)", draft-ietf-core-
object-security-01 (work in progress), December 2016.
[I-D.ietf-core-resource-directory]
Shelby, Z., Koster, M., Bormann, C., and P. Stok, "CoRE
Resource Directory", draft-ietf-core-resource-directory-09
(work in progress), October 2016.
Gerdes, et al. Expires September 14, 2017 [Page 15]
Internet-Draft CoAP-DTLS March 2017
[I-D.ietf-cose-msg]
Schaad, J., "CBOR Object Signing and Encryption (COSE)",
draft-ietf-cose-msg-24 (work in progress), November 2016.
[RFC6655] McGrew, D. and D. Bailey, "AES-CCM Cipher Suites for
Transport Layer Security (TLS)", RFC 6655,
DOI 10.17487/RFC6655, July 2012,
<http://www.rfc-editor.org/info/rfc6655>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[RFC7250] Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
Weiler, S., and T. Kivinen, "Using Raw Public Keys in
Transport Layer Security (TLS) and Datagram Transport
Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
June 2014, <http://www.rfc-editor.org/info/rfc7250>.
[RFC7251] McGrew, D., Bailey, D., Campagna, M., and R. Dugal, "AES-
CCM Elliptic Curve Cryptography (ECC) Cipher Suites for
TLS", RFC 7251, DOI 10.17487/RFC7251, June 2014,
<http://www.rfc-editor.org/info/rfc7251>.
7.3. URIs
[1] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
03#section-8.1
[2] https://tools.ietf.org/html/rfc7252#section-9
[3] https://tools.ietf.org/html/draft-ietf-ace-oauth-authz-
03#section-8.1
[4] https://tools.ietf.org/html/rfc6749#section-5.2
[5] https://tools.ietf.org/html/draft-ietf-cose-msg-23#section-12.1.2
Authors' Addresses
Stefanie Gerdes
Universitaet Bremen TZI
Postfach 330440
Bremen D-28359
Germany
Phone: +49-421-218-63906
Email: gerdes@tzi.org
Gerdes, et al. Expires September 14, 2017 [Page 16]
Internet-Draft CoAP-DTLS March 2017
Olaf Bergmann
Universitaet Bremen TZI
Postfach 330440
Bremen D-28359
Germany
Phone: +49-421-218-63904
Email: bergmann@tzi.org
Carsten Bormann
Universitaet Bremen TZI
Postfach 330440
Bremen D-28359
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Goeran Selander
Ericsson
Faroegatan 6
Kista 164 80
Sweden
Email: goran.selander@ericsson.com
Ludwig Seitz
RISE SICS
Scheelevaegen 17
Lund 223 70
Sweden
Email: ludwig.seitz@ri.se
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