Internet DRAFT - draft-hallambaker-mesh-confirm
draft-hallambaker-mesh-confirm
Network Working Group P. Hallam-Baker
Internet-Draft Comodo Group Inc.
Intended status: Informational August 16, 2017
Expires: February 17, 2018
Mesh Confirmation Protocol (Mesh/Confirm)
draft-hallambaker-mesh-confirm-01
Abstract
Mesh Confirmation Protocol (Mesh/Confirm) is a three-party Web
Service that supports a transactional second factor confirmation
mechanism that provides a superset of the capabilities of traditional
second factor authentication schemes. The three parties in the
protocol are Enquirer who posts a confirmation request, a Responder
who may or may not respond to the request and the Broker which
provides a repository to which requests and responses are posted.
This document is also available online at
http://prismproof.org/Documents/draft-hallambaker-mesh-confirm.html .
Status of This Memo
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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 February 17, 2018.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Related Specifications . . . . . . . . . . . . . . . . . 4
2.2. Defined Terms . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Requirements Language . . . . . . . . . . . . . . . . . . 4
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Confirmation vs. Authentication . . . . . . . . . . . . . 5
3.2. Use Scenarios . . . . . . . . . . . . . . . . . . . . . . 6
3.3. Use in Financial Services . . . . . . . . . . . . . . . . 6
3.4. Machine Binding . . . . . . . . . . . . . . . . . . . . . 6
3.5. Tethered Use . . . . . . . . . . . . . . . . . . . . . . 7
3.6. Co-Browser . . . . . . . . . . . . . . . . . . . . . . . 7
4. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. Parties . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Accounts . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Open and Closed Services . . . . . . . . . . . . . . . . 9
5. Confirmation Protocol . . . . . . . . . . . . . . . . . . . . 9
5.1. Creating a confirmation profile . . . . . . . . . . . . . 9
5.2. Posting a request . . . . . . . . . . . . . . . . . . . . 9
5.3. Obtaining request status. . . . . . . . . . . . . . . . . 12
5.4. List pending requests. . . . . . . . . . . . . . . . . . 13
5.5. Post a response . . . . . . . . . . . . . . . . . . . . . 14
6. Mesh/Confirm Service . . . . . . . . . . . . . . . . . . . . 16
6.1. Request Messages . . . . . . . . . . . . . . . . . . . . 16
6.1.1. Message: ConfirmRequest . . . . . . . . . . . . . . . 16
6.2. Response Messages . . . . . . . . . . . . . . . . . . . . 16
6.2.1. Message: ConfirmResponse . . . . . . . . . . . . . . 16
6.3. Imported Objects . . . . . . . . . . . . . . . . . . . . 17
6.4. Common classes . . . . . . . . . . . . . . . . . . . . . 17
6.4.1. Structure: AccountEntry . . . . . . . . . . . . . . . 17
6.4.2. Structure: EntryBase . . . . . . . . . . . . . . . . 17
6.4.3. Structure: RequestEntry . . . . . . . . . . . . . . . 18
6.4.4. Structure: ResponseEntry . . . . . . . . . . . . . . 18
6.4.5. Structure: TBSRequest . . . . . . . . . . . . . . . . 18
6.4.6. Structure: TBSResponse . . . . . . . . . . . . . . . 19
6.5. Utility Transactions . . . . . . . . . . . . . . . . . . 19
6.6. Transaction: Hello . . . . . . . . . . . . . . . . . . . 19
6.7. Enquirer Transactions . . . . . . . . . . . . . . . . . . 19
6.8. Transaction: Enquire . . . . . . . . . . . . . . . . . . 19
6.8.1. Message: EnquireRequest . . . . . . . . . . . . . . . 19
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6.8.2. Message: EnquireResponse . . . . . . . . . . . . . . 19
6.9. Transaction: Status . . . . . . . . . . . . . . . . . . . 20
6.9.1. Message: StatusRequest . . . . . . . . . . . . . . . 20
6.9.2. Message: StatusResponse . . . . . . . . . . . . . . . 20
6.10. Responder Transactions . . . . . . . . . . . . . . . . . 20
6.11. Transaction: Pending . . . . . . . . . . . . . . . . . . 20
6.11.1. Message: PendingRequest . . . . . . . . . . . . . . 21
6.11.2. Message: PendingResponse . . . . . . . . . . . . . . 21
6.12. Transaction: Respond . . . . . . . . . . . . . . . . . . 21
6.12.1. Message: RespondRequest . . . . . . . . . . . . . . 22
6.12.2. Message: RespondResponse . . . . . . . . . . . . . . 22
7. Simple Request Markup Language (SRMLv1) . . . . . . . . . . . 22
7.1. XML Schema and Content Type Identifier . . . . . . . . . 22
7.2. Design considerations and future options . . . . . . . . 23
8. Request Authentication and Authorization . . . . . . . . . . 23
8.1. Service Authentication . . . . . . . . . . . . . . . . . 23
8.2. Responder Authentication . . . . . . . . . . . . . . . . 24
8.3. Enquirer Authentication . . . . . . . . . . . . . . . . . 24
9. Implementation Status . . . . . . . . . . . . . . . . . . . . 24
9.1. Reference Implementation . . . . . . . . . . . . . . . . 25
9.1.1. Coverage: . . . . . . . . . . . . . . . . . . . . . . 25
9.1.2. Licensing . . . . . . . . . . . . . . . . . . . . . . 26
9.1.3. Implementation Experience . . . . . . . . . . . . . . 26
9.1.4. Contact Info . . . . . . . . . . . . . . . . . . . . 26
10. Security Considerations . . . . . . . . . . . . . . . . . . . 26
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 26
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 26
12.1. Normative References . . . . . . . . . . . . . . . . . . 26
12.2. Informative References . . . . . . . . . . . . . . . . . 27
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 27
1. Introduction
Authentication of end users is one of the biggest challenges for
Internet and Web security today. Despite an abundance of technology
that offers authentication mechanisms that are more robust, more
secure and easier to use, the default mechanism for user
authentication is the use of usernames and passwords.
Mesh/Confirm is a second factor authentication mechanism that binds
the user's response to the decision asked of the user. If the user
is attempting to log in to a network host, they receive a
confirmation message on a device they habitually carry such as a
watch or a smart phone asking if that is what they want to do and
they respond by accepting or rejecting the request.
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[[This figure is not viewable in this format. The figure is
available at http://prismproof.org/Documents/draft-hallambaker-mesh-
confirm.html.]]
Confirmation User Experience
Unlike traditional second factor authentication schemes, Mesh/Confirm
does not require the user to carry a special purpose 'smart' token or
to enter randomly changing PIN codes.
Mesh/Confirm is designed to make full use of the features afforded by
a modern smartphone. In particular, a Mesh/Confirm client device
MUST support a means of presenting text output to and accepting text
input from the user and a network connection. While mobile devices
offering this degree of functionality were rare in 2007, they have
since become ubiquitous. In addition to smartphones, many users now
carry smart watches and the class of wearable electronics is expected
to expand further in years to come. It is thus now a practical
proposition for a site requiring second factor authentication to
support at least a part of its users using a technology that requires
such affordances.
2. Definitions
This section presents the related specifications and standards on
which Mesh/Recrypt is built, the terms that are used as terms of art
within the documents and the terms used as requirements language.
2.1. Related Specifications
The related specifications used in the Mesh/Recrypt protocol are
described in the Mesh Architecture specification [draft-hallambaker-
mesh-architecture] [draft-hallambaker-mesh-architecture]
2.2. Defined Terms
TBS
2.3. Requirements Language
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] [RFC2119] .
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3. Overview
Second factor authentication mechanisms offer greater security over
the use of passwords alone by combining a first factor (typically a
password) with a second factor, typically a biometric or proof of
possession of a physical token.
Traditional second factor authentication techniques have suffered
from the need to distribute physical tokens and the difficulty of
ensuring that a biometric authentication is presented to a
trustworthy terminal.
The usability of traditional second factor authentication techniques
has been poor or worse. Even the simplest scheme in which the user
is required to read in a 'one time use' numeric code from the
authentication token device and enter it into a password field.
While such operations are relatively simple they require the user to
engage in a sequence of operations that bears no necessary or natural
relationship to the underlying task for which the authentication is
required.
Nor does the act of engaging in a traditional second factor scheme
offer proof of anything other than that the user was authenticated.
Any correspondence between the act of authentication and the purpose
for which the authentication was provided must be maintained
separately.
3.1. Confirmation vs. Authentication
A confirmation service addresses by cryptographically binding
responses to the request that they reply to.
A confirmation service allows the user experience to be precisely
matched to the action that the user is attempted. This is simpler
and more secure than a traditional second factor authentication
scheme. Instead of being asked to read a random number from one
device and enter it into another, the user is asked if they really
want to perform the action for which authentication is requested.
A confirmation service offers better accountability for end users
than a traditional second factor authentication scheme. An
authentication service only provides an assertion that the user was
present. A confirmation service provides an assertion that the user
was present and that they confirmed (or refused) a specific request.
For example, Alice has been granted access to a machine storing
classified data. If an authentication service is used for access
control, the authentication service log will only record the dates
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and times that Alice accessed the system. to find out if Alice
accessed a particular file on a particular day it is necessary to
consult and correlate both the authentication log of the system and
the activity log for the application.
If instead a confirmation service is used the confirmation log
contains an authenticated record of both the authentication events
and the transactions for which the authentication was requested.
3.2. Use Scenarios
A confirmation service complements rather than replaces a traditional
authentication scheme. Providing a highly secure and convenient
means of authenticating requests that carry a high degree of risk
mitigates the risk of using convenient but intrinsically low security
techniques for other actions.
3.3. Use in Financial Services
If an attacker is to profit from breaching an account with a
financial service such as a bank or a brokerage they must find a way
to move money out of the account. Thus, adding bill payment
recipients, initiating wire transfers and trading in low volume
'penny stocks' represent high risk activities.
For example: Bank of Ethel might permit customers to use a simple
username and password scheme to gain access to their account to check
their balance or to send payments to existing recipients but require
use of the second factor confirmation device for a high-risk
transaction such as adding a new payee or making a substantially
higher payment than normal.
3.4. Machine Binding
A second factor confirmation service may be combined with a machine
level authentication scheme to permit a transparent form of
authentication for low risk transactions.
For example: Alice stores her low risk authentication credentials
(e.g. usernames and passwords) using a 'cloud' service. When she
wishes to use those credentials an agent on her personal machine
fetches credentials from the cloud service as necessary. When Alice
wishes to access a site from a different machine she receives a
confirmation request on her mobile device to grant access from that
machine.
Use of such a mechanism is clearly more satisfactory when suitable
cryptographic protocols such as SAML or Kerberos are employed to
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limit the disclosure and hence possible compromise of the
credentials. The specification of such protocols is outside the
scope of this document.
3.5. Tethered Use
Although Mesh/Confirm is designed for use in a three-party scenario,
there are situations in which a two party mode may be preferred.
For example: Bob is a roadwarrior who requires access to confidential
documents stored on his laptop device from anywhere in the world,
including locations where Internet access is not possible. To permit
access in such circumstances, Bob's Mesh/Confirm client supports use
of a tethered mode in which the mobile device is connected via
Bluetooth or plugged into his laptop via a USB port.
For example: Carol is a network manager of a large computing facility
that uses Mesh/Confirm to authenticate and track all changes to
critical resources. Since Mesh/Confirm is itself a network resource
a bootstrap consideration arises: How can Carol confirm her network
configuration requests using Mesh/Confirm when the network itself is
down? Support for a tethered mode in which the Mesh/Confirm device
communicates via USB or similar wired protocol allows this use case
to be supported.
While availability of a tethered mode is clearly essential if Mesh/
Confirm is to be used in certain applications, support for this
feature outside the scope of this version of the specification.
3.6. Co-Browser
While Mesh/Confirm is designed for deployment on a secondary device,
deployment on the same device as the one for which confirmation is
being requested is also possible and can provide security benefits.
Modern Web browsers are large and complex with many features such as
support for mobile code that are incompatible with a high security
environment. Separating the confirmation protocol from the Web
Browsing protocol permits implementation in a minimal client designed
to permit detailed security analysis. Such a client might be
embedded in or support means of secure interaction with a trustworthy
operating system component.
While this means of deployment does not provide a true second factor
confirmation, it is likely to provide a sufficient degree of
authentication for many transactions.
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4. Architecture
Mesh/Confirm is a Web Service that permits an Enquirer to request
that a User confirm or reject a specified action. If the user
responds, the response is signed with a digital signature under a key
that is unique to the user account, the client and the device.
4.1. Parties
Each Mesh/Confirm protocol interaction takes place between a
connection pair of the following parties:
A party that initiates a confirmation request.
The User is the person being asked to grant or refuse
confirmation. A User MAY have multiple accounts with multiple
Broker Services.
A device that the user has bound to their broker account.
A clearing house that stores and forwards requests from Initiators
to Users Device and responses from Users to Initiators. The
Broker is only trusted to perform routing filtering and recording
of requests and responses. The Broker is not trusted with respect
to the responses returned.
The communication between the parties is shown in Figure 1.
[[This figure is not viewable in this format. The figure is
available at http://prismproof.org/Documents/draft-hallambaker-mesh-
confirm.html.]]
Mesh/Confirm Parties
4.2. Accounts
Users are identified by means of an account identifier. The display
presentation of an account identifier is the form of an RFC2822 email
address identifier without the enclosing angle braces, for example:
alice@example.com
The account identifier is used by the User when registering the use
of the confirmation service with a Broker.
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4.3. Open and Closed Services
A Mesh/Confirm service MAY be Open or Closed. An Open service
provider provides Mesh/Confirm service to the general public. A
Closed service provider only provides service to a specific
community.
For example: An Internet Service Provider or DNS Registrar might
provide an open Mesh/Confirm service as a part of their standard
service offering to customers. An employer might operate a closed
Mesh/Confirm service to be used for company business.
5. Confirmation Protocol
(Configuration).
5.1. Creating a confirmation profile
[First step is to create a mesh profile and add a confirmation
profile. This is not currently supported by the reference code, the
implementation uses the device profile instead.]
5.2. Posting a request
An Enquirer initiates a confirmation request using the EnquireRequest
message. This specifies the request to be posted, the account to
which it is posted and (optionally) the time at which the enquirer
has no further interest in receiving a response.
The signed request is a JsonWebSignature object that contains a
payload of type TBSRequest that specifies the confirmation text to be
presented to the user in SRML format, the account identifier of the
requestor and the account identifier as the responder. The
TBSRequest object MAY be encrypted.
The Responder identifier is thus specified in two separate places, in
the signed TBSRequest and in the enclosing EnquireRequest message.
Following the terminology introduced to describe the SMTP protocol,
these correspond to the 'Message to' and 'Envelope to' addresses
respectively. Separating these two functions is useful because it
allows the unsigned envelope to address to be modified to support
request routing capabilities such as aliases and group addresses
while maintaining the ability to authenticate the message to address.
For example, a party claiming to be 'Bob' calls Alice asking her to
open the pod bay doors. Following procedure, Alice requires Bob to
provide a non-repudiable confirmation of this request. Accordingly,
she uses her confirmation account alice@example.com to post a request
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to Bob's confirmation account bob@example.com asking him to confirm
the action.
Alice uses the client supplied by the reference implementation to
post this request. This client does not form part of the normative
Mesh/Confirm specification and is used here purely to illustrate the
information that a user or script needs to pass to request a
transaction.
The console command is:
confirm post bob@example.com "Open pod bay doors"
The TBSRequest is:
$$$$ extract TBS part here.
The HTTP request message is:
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POST /.well-known/confirm/HTTP/1.1
Host: example.com
Content-Length: 1095
{
"EnquireRequest": {
"Request": {
"Request": {
"unprotected": {
"dig": "S512"},
"payload": "
ewogICJUQlNSZXF1ZXN0IjogewogICAgIlRleHQiOiAiPHNybWw-PGgxPk9wZW4g
cG9kIGJheSBkb29yczwvaDE-PC9zcm1sPiIsCiAgICAiRnJvbUlEIjogImFsaWNl
QGV4YW1wbGUubmV0IiwKICAgICJUb0lEIjogImJvYkBleGFtcGxlLmNvbSJ9fQ",
"signatures": [{
"header": {
"kid": "MDQY6-SNGTN-KUOHT-ULDZW-RGD5G-ZFMMD"},
"protected": "
ewogICJhbGciOiAiUlM1MTIiLAogICJ2YWwiOiAiCmpHWmlYMU5EeGxLMmtfUm1H
dUV4NEtWSTMybkxMUmZYVnJZbXVUMDQwR1VIa3p6dEVtWG43eW1pQXh3dVl0cEUK
ZXBpUGNNNEhWMFRZbTM4TlFRdjlodyJ9",
"signature": "
VMc4Q6Ulp_BaInclyf-7rvhWISAU-MfXbvxTkfjr8vgw1iAZ5NnTPoPI85LbUChr
Eu1SR9bbkyLiIdrRcxV7ZWRH6fncpRRTiVEosI4qbxBDtFYxyjrDZlpFtfMOIkLx
RPU7fh93DSTO3NjlMs7G0C5ki_6mIDjxzylkKfBzKhV1OnqCmTp5KWVLGlW91DnH
-ci7GuE6qN2rQdDfCThiAmumGJdxtSuXbYSq1cR3WZF2uPmRMp2T0QuS3hikyDiu
-8yFGoV1keiyKPJWnrscXOVGMJmxNPSFLZkcYlR9TK-rmMNr6NnXvZ8nJsZmSxb7
5ztWbnM67mYfqQ0FdA3wDg"}]},
"ResponderAccount": "bob@example.com",
"Expire": "2017-08-17T01:15:59Z"}}}
Figure 1
A confirmation service SHOULD perform some form of request filtering
to prevent abuse (e.g. spam, denial of service). In this case the
request comes from a user with a local account which is implictly
authorized to post request messages without limit.
The confirmation service verifies the signature on the request and
returns a response message specifying the broker identifier.
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HTTP/1.1 200 OK
Date: Wed 16 Aug 2017 09:15:59
Content-Length: 162
{
"EnquireResponse": {
"Status": 201,
"StatusDescription": "Operation completed successfully",
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A"}}
Figure 2
[Note that for the sake of concise presentation, the HTTP binding
information is omitted from future examples.]
5.3. Obtaining request status.
Having posted a request, the enquirer needs to discover the result.
Since the protocol assumes that the response will be posted by a
person rather than a machine, it is likely that there will be a delay
of several seconds at least and possibly many minutes. For certain
types of confirmation, the responder might take hours or even days.
A status request is posted using the StatusRequest message. The
enquirer specifies the BrokerID of the request being enquired of.
{
"StatusRequest": {
"Cancel": false,
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A"}}
Figure 3
The service responds with the status of the request and the
Responder's response if they have replied. The first time the
enquirer asks, the request is still pending:
{
"StatusResponse": {
"Status": 201,
"StatusDescription": "Operation completed successfully",
"Response": {
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A",
"RequestStatus": "PENDING"}}}
Figure 4
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When the enquirer repeats the status request a short time later, the
responder has posted a response. The service returns the response
message returned:
{
"StatusResponse": {
"Status": 201,
"StatusDescription": "Operation completed successfully",
"Response": {
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A",
"RequestStatus": "Reply",
"Response": {
"unprotected": {
"dig": "S512"},
"payload": "
ewogICJUQlNSZXNwb25zZSI6IHsKICAgICJTaWduZWRSZXF1ZXN0IjogewogICAg
ICAidW5wcm90ZWN0ZWQiOiB7CiAgICAgICAgImRpZyI6ICJTNTEyIn0sCiAgICAg
...
ZnFRMEZkQTN3RGcifV19LAogICAgIlZhbHVlIjogdHJ1ZX19"
,
"signatures": [{
"header": {
"kid": "MD725-EFAK3-VICWN-62ZWA-53F23-UIZED"},
"protected": "
ewogICJhbGciOiAiUlM1MTIiLAogICJ2YWwiOiAiCkhBS1dpNzFYZy13ZHpaYkxS
TVlHb00xSHNDS3lFdl9hX3JyTzFCVjNyeUtBaUoxd1VhNmFVei1zWjRpajJiWnoK
NUNuclFQcmlyam1idDBRRThtd093USJ9"
,
"signature": "
LlVM3kprGKbZSIFcrCu55zNIibpzot3M0akJlJurbJE1qHrHHveKT6kb1v95VMUC
BaeIPaeHCDCeqTml4eqmm2tk9GyAfCzGpFpFD2L2gGPzAWaU0Xww3HBdoUxq04lx
z5A9--KT-fb96eAiNI2ha6GhNT6xacY4mpDp9X2dKrjBqBntg_psRO6kVDmt5A8w
Zi9SS_tRsp7dRgTXXj2AOCuJKPgu9B1kthQFfbvxYxY-xSNNmmFimn86xB8lwcxg
y9qsXX-sOG_o9FslGBcRf1aUi2Uq7D-0-nvYcRt-LWb4wFzjCLhSuxhZ3tGsHkd9
a_hmWtuifMu8Fs-NpNHo3w"
}]}}}}
Figure 5
5.4. List pending requests.
From the enquirer's point of view, the confirmation protocol is like
a very limited version of email.
The enquirer periodically polls the confirmation service to retrieve
a list of pending messages using ther PendingRequest message.
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{
"PendingRequest": {
"Responder": "bob@example.com"}}
Figure 6
The response contains a list of pending responses:
{
"PendingResponse": {
"Status": 201,
"StatusDescription": "Operation completed successfully",
"Entries": [{
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A",
"Request": {
"unprotected": {
"dig": "S512"},
"payload": "
ewogICJUQlNSZXF1ZXN0IjogewogICAgIlRleHQiOiAiPHNybWw-PGgxPk9wZW4g
cG9kIGJheSBkb29yczwvaDE-PC9zcm1sPiIsCiAgICAiRnJvbUlEIjogImFsaWNl
QGV4YW1wbGUubmV0IiwKICAgICJUb0lEIjogImJvYkBleGFtcGxlLmNvbSJ9fQ"
,
"signatures": [{
"header": {
"kid": "MDQY6-SNGTN-KUOHT-ULDZW-RGD5G-ZFMMD"},
"protected": "
ewogICJhbGciOiAiUlM1MTIiLAogICJ2YWwiOiAiCmpHWmlYMU5EeGxLMmtfUm1H
dUV4NEtWSTMybkxMUmZYVnJZbXVUMDQwR1VIa3p6dEVtWG43eW1pQXh3dVl0cEUK
ZXBpUGNNNEhWMFRZbTM4TlFRdjlodyJ9"
,
"signature": "
VMc4Q6Ulp_BaInclyf-7rvhWISAU-MfXbvxTkfjr8vgw1iAZ5NnTPoPI85LbUChr
Eu1SR9bbkyLiIdrRcxV7ZWRH6fncpRRTiVEosI4qbxBDtFYxyjrDZlpFtfMOIkLx
RPU7fh93DSTO3NjlMs7G0C5ki_6mIDjxzylkKfBzKhV1OnqCmTp5KWVLGlW91DnH
-ci7GuE6qN2rQdDfCThiAmumGJdxtSuXbYSq1cR3WZF2uPmRMp2T0QuS3hikyDiu
-8yFGoV1keiyKPJWnrscXOVGMJmxNPSFLZkcYlR9TK-rmMNr6NnXvZ8nJsZmSxb7
5ztWbnM67mYfqQ0FdA3wDg"
}]},
"ResponderAccount": "bob@example.com",
"Expire": "2017-08-17T01:15:59Z"}]}}
Figure 7
5.5. Post a response
The responder posts their response using the RespondRequest message.
This contains a ResponseEntry object which contains the response
status and the signed response.
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The payload of the signed response is a TBSResponse message which
contains the signed request and the response value. Currently only
Accept/Reject confirmations are supported and the response value is
returnes as a boolean.
The TBSResponse object is:
$$$$$ TBS extract
The request message is:
{
"RespondRequest": {
"Response": {
"BrokerID": "MBMQF-2G2XH-RCEXI-YISIK-GYGB6-A2JU3-A",
"RequestStatus": "Reply",
"Response": {
"unprotected": {
"dig": "S512"},
"payload": "
ewogICJUQlNSZXNwb25zZSI6IHsKICAgICJTaWduZWRSZXF1ZXN0IjogewogICAg
ICAidW5wcm90ZWN0ZWQiOiB7CiAgICAgICAgImRpZyI6ICJTNTEyIn0sCiAgICAg
...
ZnFRMEZkQTN3RGcifV19LAogICAgIlZhbHVlIjogdHJ1ZX19"
,
"signatures": [{
"header": {
"kid": "MD725-EFAK3-VICWN-62ZWA-53F23-UIZED"},
"protected": "
ewogICJhbGciOiAiUlM1MTIiLAogICJ2YWwiOiAiCkhBS1dpNzFYZy13ZHpaYkxS
TVlHb00xSHNDS3lFdl9hX3JyTzFCVjNyeUtBaUoxd1VhNmFVei1zWjRpajJiWnoK
NUNuclFQcmlyam1idDBRRThtd093USJ9"
,
"signature": "
LlVM3kprGKbZSIFcrCu55zNIibpzot3M0akJlJurbJE1qHrHHveKT6kb1v95VMUC
BaeIPaeHCDCeqTml4eqmm2tk9GyAfCzGpFpFD2L2gGPzAWaU0Xww3HBdoUxq04lx
z5A9--KT-fb96eAiNI2ha6GhNT6xacY4mpDp9X2dKrjBqBntg_psRO6kVDmt5A8w
Zi9SS_tRsp7dRgTXXj2AOCuJKPgu9B1kthQFfbvxYxY-xSNNmmFimn86xB8lwcxg
y9qsXX-sOG_o9FslGBcRf1aUi2Uq7D-0-nvYcRt-LWb4wFzjCLhSuxhZ3tGsHkd9
a_hmWtuifMu8Fs-NpNHo3w"
}]}}}}
Figure 8
The response value contains only the status code and description
showing the success or failure of the request.
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{
"RespondResponse": {
"Status": 201,
"StatusDescription": "Operation completed successfully"}}
Figure 9
6. Mesh/Confirm Service
The Mesh/Confirm confirmation service is a two party protocol. An
Enquirer requests a response from the
_Confirm._tcp
/.well-known/confirm
Every Confirm Service transaction consists of exactly one request
followed by exactly one response.
There is no set sequence in which operations are required to be
performed. It is not necessary to perform a Hello transaction prior
to a CreateGroup, AddMember or any other transaction.
6.1. Request Messages
6.1.1. Message: ConfirmRequest
Base class for all request messages.
[None]
6.2. Response Messages
6.2.1. Message: ConfirmResponse
Base class for all response messages. Contains only the status code
and status description fields.
A service MAY return either the response message specified for that
transaction or any parent of that message. Thus the RecryptResponse
message MAY be returned in response to any request.
[None]
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6.3. Imported Objects
The Recrypt Administration Sercice makes use of JSON objects defined
in the JOSE Signatgure and Encryption specifications.
6.4. Common classes
The following classes are referenced at multiple points in the
protocol.
6.4.1. Structure: AccountEntry
Represents the collection of data associated with an account. This
structure is not used in the protocol itself and does not appear in
the on-the-wire format. It is included here so that it can be used
as a reference point for describing the semantics of the protocol
transaction. It is possible that this record format may prove of use
in specifying archive and interchange protocols.
String (Optional)
The Responder account the request is directed to.
String [0..Many]
List of BrokerIDs of pending requests
String [0..Many]
List of BrokerIDs of responses
String [0..Many]
List of expired requests, now archived.
6.4.2. Structure: EntryBase
String (Optional)
A unique identifier for the transaction generated by the enquirer.
This identifier MAY be used to reject duplicate transactions by a
broker or Requestor.
String (Optional)
The unique identifier for the transaction generated by the broker and
returned in the corresponding Enquire transaction.
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6.4.3. Structure: RequestEntry
o Inherits: EntryBase
Describes a pending request and associated information.
JoseWebSignature (Optional)
Signed and optionally encrypted request message.
String (Optional)
The Responder account the request is directed to.
DateTime (Optional)
Date and time after which the Enquirer has no interest in the request
value. Note that a Broker MAY cancel requests according to its own
policy at any time.
6.4.4. Structure: ResponseEntry
o Inherits: EntryBase
Describes response to a pending request
String (Optional)
The status value. Valid values are PENDING, BCANCEL, ECANCEL, REPLY,
REFUSED, EXPIRED
JoseWebSignature (Optional)
Signed and optionally encrypted response message.
6.4.5. Structure: TBSRequest
String (Optional)
Text of the request
String (Optional)
String (Optional)
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6.4.6. Structure: TBSResponse
JoseWebSignature (Optional)
Boolean (Optional)
6.5. Utility Transactions
6.6. Transaction: Hello
Request: HelloRequest
Response: HelloResponse
Report service and version information.
The Hello transaction provides a means of determining which protocol
versions, message encodings and transport protocols are supported by
the service.
6.7. Enquirer Transactions
6.8. Transaction: Enquire
Request: EnquireRequest
Response: EnquireResponse
Post a confirmation request to the broker.
6.8.1. Message: EnquireRequest
o Inherits: ConfirmRequest
RequestEntry (Optional)
The request
6.8.2. Message: EnquireResponse
o Inherits: ConfirmResponse
Reports the success or failure of an Enquire transaction.
String (Optional)
A unique identifier for the transaction generated by the broker.
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6.9. Transaction: Status
Request: StatusRequest
Response: StatusResponse
Request status on a previously posted request
6.9.1. Message: StatusRequest
o Inherits: ConfirmRequest
Reports the status or of an Enquire transaction.
Boolean (Optional)
If true, the broker is abandoning the request and it should no longer
be returned to the user as an active pending request. This flag
would typically be set true on the last polling attempt made before
the Enquirer abandonds the request. It is therefore entirely valid
for a broker to return a Response value if the Cancel flag is true.
String (Optional)
The unique identifier for the transaction generated by the broker and
returned in the corresponding Enquire transaction.
6.9.2. Message: StatusResponse
o Inherits: ConfirmResponse
The result of a status request.
ResponseEntry (Optional)
6.10. Responder Transactions
6.11. Transaction: Pending
Request: PendingRequest
Response: PendingResponse
Request a list of pending transactions meeting the specified
selection criteria.
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6.11.1. Message: PendingRequest
o Inherits: ConfirmRequest
Request a list of pending requests for a specified account.
String (Optional)
The Responder account the the list of pending requests is requested
for.
String (Optional)
The BrokerID of the pending request to return.
Integer (Optional)
The maximum number of request entries to return.
Integer (Optional)
Only send request entries posted prior to the specified entry.
Integer (Optional)
Only send request entries posted after the specified entry.
6.11.2. Message: PendingResponse
o Inherits: ConfirmResponse
Contains a list of pending requests.
RequestEntry [0..Many]
List of pending requests.
6.12. Transaction: Respond
Request: RespondRequest
Response: RespondResponse
Respond to a confirmation request.
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6.12.1. Message: RespondRequest
o Inherits: ConfirmRequest
Respond to a confirmation request.
ResponseEntry (Optional)
Signed and optionally encrypted response message.
6.12.2. Message: RespondResponse
o Inherits: ConfirmResponse
Reports the success or failure of a Respond transaction.
[None]
7. Simple Request Markup Language (SRMLv1)
Confirmation requests are posted in SRML, a deliberately limited
subset of HTML. SRML is limited to four elements and one attribute.
These are:
The top-level element for an SRML request
Heading
Paragraph
Button specifying a value that the user can select.
While SRML is loosely based on the HTML forms markup, there are
important differences. The HTML markup model supports multiple
document types of which forms are only one and a single document may
contain multiple forms with multiple different action values. In an
SRML document is a single form and the form action to be performed is
impicit in the presentation of the document to the user.
7.1. XML Schema and Content Type Identifier
The MIME Content Type and schema identifier for SRML are
text/xml
http://hallambaker.com/Schemas/srml.xsd
include=Schemas\srml.md
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7.2. Design considerations and future options
The capabilities of SRML are intentionally limited to the bare
minimum. It should be possible to make use of SRML to display
options to the user on a smartwatch or other device with a highly
constrained display.
The function of the confirmation service is to provide confirmation
of an action that was initiated elsewhere. It is therefore
inappropriate for this or any future version of SRML to offer
extensive data entry or validation capabilities. SRML applications
MUST NOT support any form of scripting or active code extensions to
SRML content.
It might prove advantageous in the future to extend the input types
to include simple form elements such as checkboxes, numeric fields,
text choices and possibly free form text.
8. Request Authentication and Authorization
The current version of the protocol does not address the question of
how service requests are to be authorized or authenticated.
A triple lock security approach is anticipated in which cryptographic
enhancements are applied at three separate levels to provide
different security controls:
Basic confidentiality and integrity controls are provided using
TLS with a server-side certificate. It is necessary to provide
encryption at this layer to protect confidentiality of meta-data.
Mutual authentication of the client and service is provided at the
presentation layer. In the default JWB binding, this is provided
within the HTTP content payload. The use of encryption at the
presentation is optional.
Confirmation requests and responses are signed by the Enquirer and
Responder respectively. This provides for non-repudiation of
messages.
8.1. Service Authentication
Since the responder is identified by the responder?s account, Minimal
Validation is sufficient but Domain Validation is preferred. These
credentials MAY be bound using a strong DNS name.
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8.2. Responder Authentication
The responder is authenticated by means of the user?s Mesh profile.
The ability to delegate access to a confirmation account might be
useful in certain circumstances.
8.3. Enquirer Authentication
Authentication of the Enquirer presents very different challenges to
authentication of the Service or the Responder as it is the only part
of the service that is ?open?. It is thus likely to be the target of
abuse (i.e. spam). It is therefore important that the authentication
mechanism enable appropriate authorization and accountability
strategies.
For example, one strategy to control abuse might be to permit
enquirers to post requests if they were signed with a key
authenticated by an Extended Validation certificate or were sent by
an enquirer approved by the responder to whom the request was
directed. In the first case, abuse is mitigated by an accountability
control, in the second by explicit authorization of the sender.
While it is possible to implement such a strategy in the responder
application, this approach is clearly limiting. Filtering of
messages in the service avoids the need to synchronize policy across
the user?s confirmation devices and protects possibly limited
wireless bandwidth by performing policy enforcement in the service
rather than the responder?s device.
Mesh/Confirm does not provide a mechanism for specifying such a
security policy. Leaving this requirement to a separate service
allows for a protocol that can specify policy for multiple modes of
communication. For instance, a customer of a bank might permit the
bank to send confirmation messages and to deliver statements by email
but not to make contact by voice or video calls.
9. Implementation Status
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC6982]
[RFC6982] . The description of implementations in this section is
intended to assist the IETF in its decision processes in progressing
drafts to RFCs. Please note that the listing of any individual
implementation here does not imply endorsement by the IETF.
Furthermore, no effort has been spent to verify the information
presented here that was supplied by IETF contributors. This is not
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intended as, and must not be construed to be, a catalog of available
implementations or their features. Readers are advised to note that
other implementations may exist.
According to [RFC6982] [RFC6982] , "this will allow reviewers and
working groups to assign due consideration to documents that have the
benefit of running code, which may serve as evidence of valuable
experimentation and feedback that have made the implemented protocols
more mature. It is up to the individual working groups to use this
information as they see fit".
9.1. Reference Implementation
Organization: Comodo Group Inc.
Implementer: Phillip Hallam-Baker
Maturity: Experimental Prototype
This implementation was used to produce the reference section and all
the examples in this document. Since the conversion of specification
to code is automatic, there is a high degree of assurance that the
reference implementation is consistent with this document.
9.1.1. Coverage:
The draft-xx branch describes the code used to create version xx of
this document.
The main current limitations are that the code only supports RSA key
pairs and for ease of development the server does not persist keys
across sessions. Nor does the implementation currently support the
HTTP payload authentication and encryption layer or make use of TLS.
These could be easily fixed.
The client and server are implemented as libraries that may be called
from a multi-protocol server. A standalone server will be provided
in a future release.
Only the JSON encoding is currently implemented. The JSON-B, JSON-C,
ASN.1 and TLS Schema implementations are all supported by the code
generation tool but not currently implemented as the build tool
bindings for those encodings have not yet been finalized or
documented.
The key restrictions for TLS key exchange have not yet been
implemented.
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The code has only been tested on Windows 10 but passed compatibility
testing for both Mono and dotNetCore 10 run times which should in
theory permit use on Linux and OSX platforms.
9.1.2. Licensing
The code is released under an MIT License
Source code is available from GitHub at
https://github.com/hallambaker/Mathematical-Mesh
9.1.3. Implementation Experience
The implementation and specification documentation were developed in
Visual Studio using the PHB Build Tools suite.
9.1.4. Contact Info
Contact Phillip Hallam-Baker phill@hallambaker.com
10. Security Considerations
Consider spam control, how do users prevent unwanted requests? (EV
accreditation, filtering at Broker)
People deploying Mesh/Confirm as a means of controlling access to
networking infrastructure must consider the bootstrap issue. In
particular since Mesh/Confirm requires Internet access the network
administrator must ensure that it is possible to manage the network
resources necessary to support an SXS service when that service is
down.
11. Acknowledgements
12. References
12.1. Normative References
[draft-hallambaker-mesh-architecture]
Hallam-Baker, P., "Mathematical Mesh: Architecture",
draft-hallambaker-mesh-architecture-03 (work in progress),
May 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997.
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12.2. Informative References
[RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", RFC 6982,
DOI 10.17487/RFC6982, July 2013.
Author's Address
Phillip Hallam-BakerPhillip Hallam-Baker
Comodo Group Inc.
Email: philliph@comodo.com
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