draft-ietf-oauth-revocation-07.txt   draft-ietf-oauth-revocation-08.txt 
OAuth Working Group T. Lodderstedt, Ed. OAuth Working Group T. Lodderstedt, Ed.
Internet-Draft Deutsche Telekom AG Internet-Draft Deutsche Telekom AG
Intended status: Standards Track S. Dronia Intended status: Standards Track S. Dronia
Expires: October 17, 2013 M. Scurtescu Expires: November 20, 2013 M. Scurtescu
Google Google
April 15, 2013 May 19, 2013
Token Revocation OAuth Token Revocation
draft-ietf-oauth-revocation-07 draft-ietf-oauth-revocation-08
Abstract Abstract
This document proposes an additional endpoint for OAuth authorization This document proposes an additional endpoint for OAuth authorization
servers, which allows clients to notify the authorization server that servers, which allows clients to notify the authorization server that
a previously obtained refresh or access token is no longer needed. a previously obtained refresh or access token is no longer needed.
This allows the authorization server to cleanup security credentials. This allows the authorization server to cleanup security credentials.
A revocation request will invalidate the actual token and, if A revocation request will invalidate the actual token and, if
applicable, other tokens based on the same authorization grant. applicable, other tokens based on the same authorization grant.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 17, 2013. This Internet-Draft will expire on November 20, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Token Revocation . . . . . . . . . . . . . . . . . . . . . . 3 2. Token Revocation . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Revocation Request . . . . . . . . . . . . . . . . . . . 3 2.1. Revocation Request . . . . . . . . . . . . . . . . . . . 3
2.2. Revocation Response . . . . . . . . . . . . . . . . . . . 5 2.2. Revocation Response . . . . . . . . . . . . . . . . . . . 5
2.2.1. Error Response . . . . . . . . . . . . . . . . . . . 5 2.2.1. Error Response . . . . . . . . . . . . . . . . . . . 5
2.3. Cross-Origin Support . . . . . . . . . . . . . . . . . . 5 2.3. Cross-Origin Support . . . . . . . . . . . . . . . . . . 5
3. Implementation Note . . . . . . . . . . . . . . . . . . . . . 6 3. Implementation Note . . . . . . . . . . . . . . . . . . . . . 6
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4.1. OAuth Extensions Error Registration . . . . . . . . . . . 7
5.1. OAuth Extensions Error Registration . . . . . . . . . . . 7 4.1.1. The "unsupported_token_type" Error Value . . . . . . 7
5.1.1. The "unsupported_token_type" Error Value . . . . . . 7 4.1.2. OAuth Token Type Hint Registry . . . . . . . . . . . 7
5.1.2. OAuth Token Type Hint Registry . . . . . . . . . . . 7 4.1.2.1. Registration Template . . . . . . . . . . . . . . 8
5.1.2.1. Registration Template . . . . . . . . . . . . . . 8 4.1.2.2. Initial Registry Contents . . . . . . . . . . . . 8
5.1.2.2. Initial Registry Contents . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Normative References . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . 9
7.2. Informative References . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
The OAuth 2.0 core specification [RFC6749] defines several ways for a The OAuth 2.0 core specification [RFC6749] defines several ways for a
client to obtain refresh and access tokens. This specification client to obtain refresh and access tokens. This specification
supplements the core specification with a mechanism to revoke both supplements the core specification with a mechanism to revoke both
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end-user. end-user.
2. Token Revocation 2. Token Revocation
Implementations MUST support the revocation of refresh tokens and Implementations MUST support the revocation of refresh tokens and
SHOULD support the revocation of access tokens (see Implementation SHOULD support the revocation of access tokens (see Implementation
Note). Note).
The client requests the revocation of a particular token by making an The client requests the revocation of a particular token by making an
HTTP POST request to the token revocation endpoint URL. This URL MAY HTTP POST request to the token revocation endpoint URL. This URL MAY
include a query component. include a query component. The means to obtain the location of the
revocation endpoint is out of scope of this specification. For
The means to obtain the location of the revocation endpoint is out of example, the client developer may consult the server's documentation
scope of this specification. For example, the client developer may or automatic discovery may be used. As this endpoint is handling
consult the server's documentation or automatic discovery may be security credentials, the endpoint location needs to be obtained from
used. As this endpoint is handling security credentials, the a trustworthy source.
endpoint location need be obtained from a trustworthy source.
Since requests to the token revocation endpoint result in the Since requests to the token revocation endpoint result in the
transmission of plain text credentials in the HTTP request, the transmission of plain text credentials in the HTTP request, the
authorization server MUST require the use of a transport-layer authorization server MUST require the use of a transport-layer
security mechanism when sending requests to the token revocation security mechanism when sending requests to the token revocation
endpoints. The authorization server MUST support TLS 1.0 endpoints. The authorization server MUST support TLS 1.0
([RFC2246]), SHOULD support TLS 1.2 ([RFC5246]) and its future ([RFC2246]), SHOULD support TLS 1.2 ([RFC5246]) and its future
replacements, and MAY support additional transport-layer mechanisms replacements, and MAY support additional transport-layer mechanisms
meeting its security requirements. meeting its security requirements.
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token_type_hint OPTIONAL. A hint about the type of the token token_type_hint OPTIONAL. A hint about the type of the token
submitted for revocation. Clients MAY pass this parameter in submitted for revocation. Clients MAY pass this parameter in
order to help the authorization server to optimize the token order to help the authorization server to optimize the token
lookup. If the server is unable to locate the token using lookup. If the server is unable to locate the token using
the given hint, it MUST extend its search accross all of its the given hint, it MUST extend its search accross all of its
supported token types. An authorization server MAY ignore supported token types. An authorization server MAY ignore
this parameter, particularly if it is able to detect the this parameter, particularly if it is able to detect the
token type automatically. This specification defines two token type automatically. This specification defines two
such values: such values:
* access_token An Access Token as defined in [RFC6749] * access_token: An Access Token as defined in [RFC6749]
section 1.4 section 1.4
* refresh_token A Refresh Token as defined in [RFC6749] * refresh_token: A Refresh Token as defined in [RFC6749]
section 1.5 section 1.5
Specific implementations, profiles, and extensions of this Specific implementations, profiles, and extensions of this
specification MAY define other values for this parameter specification MAY define other values for this parameter
using the registry defined in Section 5.1.2. parameter using the registry defined in Section 4.1.2.
The client also includes its authentication credentials as described The client also includes its authentication credentials as described
in Section 2.3. of [RFC6749]. in Section 2.3. of [RFC6749].
For example, a client may request the revocation of a refresh token For example, a client may request the revocation of a refresh token
with the following request (line breaks are for display purposes with the following request:
only):
POST /revoke HTTP/1.1 POST /revoke HTTP/1.1
Host: server.example.com Host: server.example.com
Content-Type: application/x-www-form-urlencoded Content-Type: application/x-www-form-urlencoded
Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
token=45ghiukldjahdnhzdauz&token_type_hint=refresh_token token=45ghiukldjahdnhzdauz&token_type_hint=refresh_token
The authorization server first validates the client credentials (in The authorization server first validates the client credentials (in
case of a confidential client) and then verifies whether the token case of a confidential client) and then verifies whether the token
was issued to the client making the revocation request. If this was issued to the client making the revocation request. If this
validation fails, the request is refused and the client is informed validation fails, the request is refused and the client is informed
of the error by the authorization server as described below. of the error by the authorization server as described below.
In the next step, the authorization server invalidates the token. In the next step, the authorization server invalidates the token.
The client MUST assume the revocation is immediate upon receipt of an The client MUST assume the revocation is immediate upon the receipt
HTTP 200 response from the server. The client MUST NOT use the token of an HTTP 200 response from the server. The client MUST NOT use the
again after the revocation. token again after the revocation.
Depending on the authorization server's revocation policy, the Depending on the authorization server's revocation policy, the
revocation of a particular token may cause the revocation of related revocation of a particular token may cause the revocation of related
tokens and the underlying authorization grant. If the particular tokens and the underlying authorization grant. If the particular
token is a refresh token and the authorization server supports the token is a refresh token and the authorization server supports the
revocation of access tokens, then the authorization server SHOULD revocation of access tokens, then the authorization server SHOULD
also invalidate all access tokens based on the same authorization also invalidate all access tokens based on the same authorization
grant (see Implementation Note). If the token passed to the request grant (see Implementation Note). If the token passed to the request
is an access token, the server MAY decide to revoke the respective is an access token, the server MAY decide to revoke the respective
refresh token as well. refresh token as well.
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unexpected token invalidation at any time. Independent of the unexpected token invalidation at any time. Independent of the
revocation mechanism specified in this document, resource owners may revocation mechanism specified in this document, resource owners may
decide to revoke authorization grants or the authorization server may decide to revoke authorization grants or the authorization server may
invalidate tokens in order to mitigate security threats. Thus having invalidate tokens in order to mitigate security threats. Thus having
different server policies with respect to cascading the revocation of different server policies with respect to cascading the revocation of
tokens should not pose interoperability problems. tokens should not pose interoperability problems.
2.2. Revocation Response 2.2. Revocation Response
The authorization server responds with HTTP status code 200 if the The authorization server responds with HTTP status code 200 if the
token has been revoked sucessfully or if the client submited an token has been revoked sucessfully or if the client submitted an
invalid token. The content of the response body does not matter as invalid token. The content of the response body does not matter as
all information is conveyed in the response code. all information is conveyed in the response code.
An invalid token type hint value is ignored by the authorization
server and does not influence the revocation response.
2.2.1. Error Response 2.2.1. Error Response
The error presentation conforms to the defintion in section 5.2 of The error presentation conforms to the defintion in section 5.2 of
[RFC6749]. The following additional error code is defined for the [RFC6749]. The following additional error code is defined for the
token revocation endpoint: token revocation endpoint:
unsupported_token_type The authorization server does not support the unsupported_token_type The authorization server does not support the
revocation of the presented token type. I.e. the client revocation of the presented token type. I.e. the client
tried to revoke an access token on a server not supporting tried to revoke an access token on a server not supporting
this feature. this feature.
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refreshed at any time using the corresponding refresh tokens. This refreshed at any time using the corresponding refresh tokens. This
allows the authorization server to impose a limit on the time revoked allows the authorization server to impose a limit on the time revoked
access tokens are in use. access tokens are in use.
Which approach of token revocation is chosen will depend on the Which approach of token revocation is chosen will depend on the
overall system design and on the application service provider's risk overall system design and on the application service provider's risk
analysis. The cost of revocation in terms of required state and analysis. The cost of revocation in terms of required state and
communication overhead is ultimately the result of the desired communication overhead is ultimately the result of the desired
security properties. security properties.
4. Acknowledgements 4. IANA Considerations
We would like to thank Peter, Mauritius, Amanda Anganes, Mark Wubben,
Hannes Tschofenig, Michiel de Jong, Doug Foiles, Paul Madsen, George
Fletcher, Sebastian Ebling, Christian Stuebner, Brian Campbell, Igor
Faynberg, Lukas Rosenstock, and Justin Richer for their valuable
feedback.
5. IANA Considerations
5.1. OAuth Extensions Error Registration 4.1. OAuth Extensions Error Registration
This specification registers the following error values in the OAuth This specification registers the following error values in the OAuth
Extensions Error registry defined in [RFC6749]. Extensions Error registry defined in [RFC6749].
5.1.1. The "unsupported_token_type" Error Value 4.1.1. The "unsupported_token_type" Error Value
Error name unsupported_token_type Error name unsupported_token_type
Error usage location revocation endpoint error response Error usage location revocation endpoint error response
Related protocol extension Token Revocation Endpoint Related protocol extension Token Revocation Endpoint
Change controller IETF Change controller IETF
Specification document(s) [this document] Specification document(s) [this document]
5.1.2. OAuth Token Type Hint Registry 4.1.2. OAuth Token Type Hint Registry
This specification establishes the OAuth Token Type Hint registry. This specification establishes the OAuth Token Type Hint registry.
Possible values of the parameter "token_type_hint" (see Section 2.1) Possible values of the parameter "token_type_hint" (see Section 2.1)
are registered with a Specification Required ([RFC5226]) after a two- are registered with a Specification Required ([RFC5226]) after a two-
week review period on the TBD@ietf.org mailing list, on the advice of week review period on the TBD@ietf.org mailing list, on the advice of
one or more Designated Experts. However, to allow for the allocation one or more Designated Experts. However, to allow for the allocation
of values prior to publication, the Designated Expert(s) may approve of values prior to publication, the Designated Expert(s) may approve
registration once they are satisfied that such a specification will registration once they are satisfied that such a specification will
be published. Registration requests must be sent to the TBD@ietf.org be published. Registration requests must be sent to the TBD@ietf.org
mailing list for review and comment, with an appropriate subject mailing list for review and comment, with an appropriate subject
(e.g., "Request for parameter: example"). Within the review period, (e.g., "Request for parameter: example"). Within the review period,
the Designated Expert(s) will either approve or deny the registration the Designated Expert(s) will either approve or deny the registration
request, communicating this decision to the review list and IANA. request, communicating this decision to the review list and IANA.
Denials should include an explanation and, if applicable, suggestions Denials should include an explanation and, if applicable, suggestions
as to how to make the request successful. IANA must only accept as to how to make the request successful. IANA must only accept
registry updates from the Designated Expert(s) and should direct all registry updates from the Designated Expert(s) and should direct all
requests for registration to the review mailing list. requests for registration to the review mailing list.
5.1.2.1. Registration Template 4.1.2.1. Registration Template
Hint Value: The additional value, which can be used to indicate a Hint Value: The additional value, which can be used to indicate a
certain token type to the authorization server. certain token type to the authorization server.
Change controller: For Standards Track RFCs, state "IETF". For Change controller: For Standards Track RFCs, state "IETF". For
others, give the name of the responsible party. Other details others, give the name of the responsible party. Other details
(e.g., postal address, email address, home page URI) may also be (e.g., postal address, email address, home page URI) may also be
included. included.
Specification document(s): Reference to the document(s) that specify Specification document(s): Reference to the document(s) that specify
the type, preferably including a URI that can be used to retrieve the type, preferably including a URI that can be used to retrieve
a copy of the document(s). An indication of the relevant sections a copy of the document(s). An indication of the relevant sections
may also be included but is not required. may also be included but is not required.
5.1.2.2. Initial Registry Contents 4.1.2.2. Initial Registry Contents
The OAuth Token Type Hint registry's initial contents are: The OAuth Token Type Hint registry's initial contents are:
o Hint Value: access_token o Hint Value: access_token
o Change controller: IETF o Change controller: IETF
o Specification document(s): [this document] o Specification document(s): [this document]
o Response type name: refresh_token o Hint Value: refresh_token
o Change controller: IETF o Change controller: IETF
o Specification document(s): [this document] o Specification document(s): [this document]
6. Security Considerations 5. Security Considerations
If the authorization server does not support access token revocation, If the authorization server does not support access token revocation,
access tokens will not be immediately invalidated when the access tokens will not be immediately invalidated when the
corresponding refresh token is revoked. Deployments must take this corresponding refresh token is revoked. Deployments must take this
into account when conducting their security risk analysis. into account when conducting their security risk analysis.
Cleaning up tokens using revocation contributes to overall security Cleaning up tokens using revocation contributes to overall security
and privacy since it reduces the likelihood for abuse of abandoned and privacy since it reduces the likelihood for abuse of abandoned
tokens. This specification in general does not intend to provide tokens. This specification in general does not intend to provide
countermeasures against token theft and abuse. For a discussion of countermeasures against token theft and abuse. For a discussion of
respective threats and countermeasures, consult the security respective threats and countermeasures, consult the security
considerations given in section 10 of the OAuth core specification considerations given in section 10 of the OAuth core specification
[RFC6749] and the OAuth threat model document [RFC6819]. [RFC6749] and the OAuth threat model document [RFC6819].
Malicious clients could attempt to use the new endpoint to launch Malicious clients could attempt to use the new endpoint to launch
denial of service attacks on the authorization server. Appropriate denial of service attacks on the authorization server. Appropriate
countermeasures, which should be in place for the token endpoint as countermeasures, which should be in place for the token endpoint as
well, MUST be applied to the revocation endpoint (see [RFC6819], well, MUST be applied to the revocation endpoint (see [RFC6819],
section 4.4.1.11). section 4.4.1.11). Specifically, invalid token type hints may
misguide the authorization server and cause additional database
lookups. Care MUST be taken to prevent malicious clients from
exploiting this feature to launch denial of service attacks.
A malicious client may attempt to guess valid tokens on this endpoint A malicious client may attempt to guess valid tokens on this endpoint
by making revocation requests against potential token strings. by making revocation requests against potential token strings.
According to this specification, a client's request must contain a According to this specification, a client's request must contain a
valid client_id, in the case of a public client, or valid client valid client_id, in the case of a public client, or valid client
credentials, in the case of a confidential client. The token being credentials, in the case of a confidential client. The token being
revoked must also belong to the requesting client. If an attacker is revoked must also belong to the requesting client. If an attacker is
able to successfully guess a public client's client_id and one of able to successfully guess a public client's client_id and one of
their tokens, or a private client's credentials and one of their their tokens, or a private client's credentials and one of their
tokens, they could do much worse damage by using the token elsewhere tokens, they could do much worse damage by using the token elsewhere
than by revoking it. If they chose to revoke the token, the than by revoking it. If they chose to revoke the token, the
legitimate client will lose its authorization grant and will need to legitimate client will lose its authorization grant and will need to
prompt the user again. No further damage is done and the guessed prompt the user again. No further damage is done and the guessed
token is now worthless. token is now worthless.
Since the revocation endpoint is handling security credentials, Since the revocation endpoint is handling security credentials,
clients need to obtain its location from a trustworthy source only. clients need to obtain its location from a trustworthy source only.
Otherwise, an attacker could capture valid security tokens by Otherwise, an attacker could capture valid security tokens by
utilizing a counterfeit revocation endpoint. utilizing a counterfeit revocation endpoint. Moreover in order to
detect counterfeit revocation endpoints, clients MUST authenticate
the revocation endpoint (certificate validation etc.).
6. Acknowledgements
We would like to thank Peter Mauritius, Amanda Anganes, Mark Wubben,
Hannes Tschofenig, Michiel de Jong, Doug Foiles, Paul Madsen, George
Fletcher, Sebastian Ebling, Christian Stuebner, Brian Campbell, Igor
Faynberg, Lukas Rosenstock, and Justin Richer for their valuable
feedback.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", [RFC2246] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999. RFC 2246, January 1999.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008. (TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework", RFC [RFC6749] Hardt, D., "The OAuth 2.0 Authorization Framework", RFC
6749, October 2012. 6749, October 2012.
7.2. Informative References 7.2. Informative References
[RFC6819] Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0 [RFC6819] Lodderstedt, T., McGloin, M., and P. Hunt, "OAuth 2.0
Threat Model and Security Considerations", RFC 6819, Threat Model and Security Considerations", RFC 6819,
skipping to change at page 10, line 20 skipping to change at page 10, line 30
[W3C.WD-cors-20120403] [W3C.WD-cors-20120403]
Kesteren, A., "Cross-Origin Resource Sharing", World Wide Kesteren, A., "Cross-Origin Resource Sharing", World Wide
Web Consortium LastCall WD-cors-20120403, April 2012, Web Consortium LastCall WD-cors-20120403, April 2012,
<http://www.w3.org/TR/2012/WD-cors-20120403>. <http://www.w3.org/TR/2012/WD-cors-20120403>.
[jsonp] Ippolito, B., "Remote JSON - JSONP", December 2005, <http: [jsonp] Ippolito, B., "Remote JSON - JSONP", December 2005, <http:
//bob.pythonmac.org/archives/2005/12/05/remote-json- //bob.pythonmac.org/archives/2005/12/05/remote-json-
jsonp>. jsonp>.
[portable-contacts]
Smarr, J., "Portable Contacts 1.0 Draft C", August 2008,
<http://portablecontacts.net/>.
Authors' Addresses Authors' Addresses
Torsten Lodderstedt (editor) Torsten Lodderstedt (editor)
Deutsche Telekom AG Deutsche Telekom AG
Email: torsten@lodderstedt.net Email: torsten@lodderstedt.net
Stefanie Dronia Stefanie Dronia
Email: sdronia@gmx.de Email: sdronia@gmx.de
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