draft-ietf-oauth-spop-04.txt   draft-ietf-oauth-spop-05.txt 
OAuth Working Group N. Sakimura, Ed. OAuth Working Group N. Sakimura, Ed.
Internet-Draft Nomura Research Institute Internet-Draft Nomura Research Institute
Intended status: Standards Track J. Bradley Intended status: Standards Track J. Bradley
Expires: May 16, 2015 Ping Identity Expires: June 08, 2015 Ping Identity
N. Agarwal N. Agarwal
Google Google
November 12, 2014 December 07, 2014
Symmetric Proof of Possession for the OAuth Authorization Code Grant Symmetric Proof of Possession for the OAuth Authorization Code Grant
draft-ietf-oauth-spop-04 draft-ietf-oauth-spop-05
Abstract Abstract
The OAuth 2.0 public client utilizing Authorization Code Grant (RFC The OAuth 2.0 public client utilizing Authorization Code Grant (RFC
6749 - 4.1) is susceptible to the code interception attack. This 6749 - 4.1) is susceptible to the code interception attack. This
specification describes a mechanism that acts as a control against specification describes a mechanism that acts as a control against
this threat. this threat.
Status of This Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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
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This Internet-Draft will expire on May 16, 2015. This Internet-Draft will expire on June 08, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Protocol Flow . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. Client creates a code verifier . . . . . . . . . . . . . 5 4.1. Client creates a code verifier . . . . . . . . . . . . . . 4
4.2. Client creates the code challenge . . . . . . . . . . . . 5 4.2. Client creates the code challenge . . . . . . . . . . . . 5
4.3. Client sends the code challenge with the authorization 4.3. Client sends the code challenge with the authorization
request . . . . . . . . . . . . . . . . . . . . . . . . . 6 request . . . . . . . . . . . . . . . . . . . . . . . . . 5
4.4. Server returns the code . . . . . . . . . . . . . . . . . 6 4.4. Server returns the code . . . . . . . . . . . . . . . . . 5
4.4.1. Error Response . . . . . . . . . . . . . . . . . . . 6 4.4.1. Error Response . . . . . . . . . . . . . . . . . . . . 6
4.5. Client sends the code and the secret to the token 4.5. Client sends the code and the secret to the token endpoint 6
endpoint . . . . . . . . . . . . . . . . . . . . . . . . 7 4.6. Server verifies code_verifier before returning the tokens 6
4.6. Server verifies code_verifier before returning the tokens 7 5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6.1. OAuth Parameters Registry . . . . . . . . . . . . . . . . 7
6.1. OAuth Parameters Registry . . . . . . . . . . . . . . . . 8 6.2. SPOP Code Challenge Method Registry . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6.2.1. Registration Template . . . . . . . . . . . . . . . . 8
7.1. Entropy of the code verifier . . . . . . . . . . . . . . 8 6.2.2. Initial Registry Contents . . . . . . . . . . . . . . 8
7.2. Protection against eavesdroppers . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
7.3. Checking the Server support . . . . . . . . . . . . . . . 9 7.1. Entropy of the code verifier . . . . . . . . . . . . . . . 9
7.4. OAuth security considerations . . . . . . . . . . . . . . 9 7.2. Protection against eavesdroppers . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 7.3. Checking the Server support . . . . . . . . . . . . . . . 9
9. Revision History . . . . . . . . . . . . . . . . . . . . . . 10 7.4. OAuth security considerations . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 11 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . 11 9. Revision History . . . . . . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 11 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendix A. Notes on implementing base64url encoding without 10.1. Normative References . . . . . . . . . . . . . . . . . . 10
padding . . . . . . . . . . . . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Appendix A. Notes on implementing base64url encoding without paddi 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction 1. Introduction
Public clients in OAuth 2.0 [RFC6749] are susceptible to the Public clients in OAuth 2.0 [RFC6749] are susceptible to the
authorization "code" interception attack. A malicious client authorization "code" interception attack. A malicious client
intercepts the authorization code returned from the authorization intercepts the authorization code returned from the authorization
endpoint within communication path not protected by TLS, such as endpoint within communication path not protected by TLS, such as
inter-app communication, and uses it to obtain the access token. inter-app communication, and uses it to obtain the access token.
This is possible on a public client as there is no client secret This is possible on a public client as there is no client secret
associated for it to be sent to the token endpoint. This is associated for it to be sent to the token endpoint. This is
especially true on Smartphone applications where the authorization especially true on Smartphone applications where the authorization
code can be returned through custom URL Schemes where the same scheme code can be returned through custom URL Schemes where the same scheme
can be registered by multiple applications. Under this scenario, the can be registered by multiple applications. Under this scenario, the
mitigation strategy stated in section 4.4.1 of [RFC6819] does not mitigation strategy stated in section 4.4.1 of [RFC6819] does not
work as they rely on per-client instance secret or per client work as they rely on per-client instance secret or per client
instance redirect URI. instance redirect URI.
To mitigate this attack, this extension utilizes a dynamically To mitigate this attack, this extension utilizes a dynamically
created cryptographically random key called 'code verifier'. The created cryptographically random key called 'code verifier'. The code
code verifier is created for every authorization request and its verifier is created for every authorization request and its
transformed value, called 'code challenge', is sent to the transformed value, called 'code challenge', is sent to the
authorization server to obtain the authorization code. The authorization server to obtain the authorization code. The
authorization "code" obtained is then sent to the token endpoint with authorization "code" obtained is then sent to the token endpoint with
the 'code verifier' and the server compares it with the previously the 'code verifier' and the server compares it with the previously
received request code so that it can perform the proof of possession received request code so that it can perform the proof of possession
of the 'code verifier' by the client. This works as the mitigation of the 'code verifier' by the client. This works as the mitigation
since the attacker would not know this one-time key. since the attacker would not know this one-time key.
1.1. Protocol Flow 1.1. Protocol Flow
+--------+ +---------------+ +--------+ +---------------+
| |--(A)-- Authorization Request --->| | | |--(A)-- Authorization Request --->| |
| | + t(code_verifier), t | Resource | | | + t(code_verifier), t | Resource |
| | | Owner | | | | Owner |
| |<-(B)--- Authorization Grant -----| | | |<-(B)--- Authorization Grant -----| |
| | +---------------+ | | +---------------+
| Client | | Client |
| | +---------------+ | | +---------------+
| |--(C)--- Access Token Request --->| | | |--(C)--- Access Token Request --->| |
| | + code_verifier | Authorization | | | + code_verifier | Authorization |
| | | Server | | | | Server |
| |<-(D)------ Access Token ---------| | | |<-(D)------ Access Token ---------| |
+--------+ +---------------+ +--------+ +---------------+
Figure 1: Abstract Protocol Flow
This specification adds additional parameters to the OAuth 2.0 This specification adds additional parameters to the OAuth 2.0
Authorization and Access Token Requests, shown in abstract form in Authorization and Access Token Requests, shown in abstract form in
Figure 1. Figure 1.
A. The client creates and records a secret named the "code_verifier", A. The client creates and records a secret named the "code_verifier",
and derives a transformed version "t(code_verifier)" (referred to and derives a transformed version "t(code_verifier)" (referred to
as the "code_challenge") which is sent in the OAuth 2.0 as the "code_challenge") which is sent in the OAuth 2.0
Authorization Request, along with the transformation method "t". Authorization Request, along with the transformation method "t".
B. The resource owner responds as usual, but records B. The resource owner responds as usual, but records
"t(code_verifier)" and the transformation method. "t(code_verifier)" and the transformation method.
C. The client then sends the code to the Access Token Request as C. The client then sends the code to the Access Token Request as
usual, but includes the "code_verifier" secret generated at (A). usual, but includes the "code_verifier" secret generated at (A).
D. The authorization server transforms "code_verifier" and compares D. The authorization server transforms "code_verifier" and compares
it to "t(code_verifier)" from (B). Access is denied if they are it to "t(code_verifier)" from (B). Access is denied if they are
not equal. not equal.
An attacker who intercepts the Authorization Grant at (B) is unable An attacker who intercepts the Authorization Grant at (B) is unable
to redeem it for an Access Token, as they are not in possession of to redeem it for an Access Token, as they are not in possession of
the "code_verifier" secret. the "code_verifier" secret.
2. Notational Conventions 2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in Key "OPTIONAL" in this document are to be interpreted as described in Key
words for use in RFCs to Indicate Requirement Levels [RFC2119]. If words for use in RFCs to Indicate Requirement Levels [RFC2119]. If
these words are used without being spelled in uppercase then they are these words are used without being spelled in uppercase then they are
to be interpreted with their normal natural language meanings. to be interpreted with their normal natural language meanings.
This specification uses the Augmented Backus-Naur Form (ABNF) This specification uses the Augmented Backus-Naur Form (ABNF)
notation of [RFC5234]. notation of [RFC5234].
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ASCII(STRING) denotes the octets of the ASCII [US-ASCII] ASCII(STRING) denotes the octets of the ASCII [US-ASCII]
representation of STRING. representation of STRING.
The concatenation of two values A and B is denoted as A || B. The concatenation of two values A and B is denoted as A || B.
3. Terminology 3. Terminology
In addition to the terms defined in OAuth 2.0 [RFC6749], this In addition to the terms defined in OAuth 2.0 [RFC6749], this
specification defines the following terms: specification defines the following terms:
code verifier A cryptographically random string that is used to code verifier A cryptographically random string that is used to
correlate the authorization request to the token request. correlate the authorization request to the token request.
code challenge A challenge derived from the code verifier that is
code challenge A challenge derived from the code verifier that is
sent in the authorization request, to be verified against later. sent in the authorization request, to be verified against later.
Base64url Encoding Base64 encoding using the URL- and filename-safe
Base64url Encoding Base64 encoding using the URL- and filename-safe
character set defined in Section 5 of RFC 4648 [RFC4648], with all character set defined in Section 5 of RFC 4648 [RFC4648], with all
trailing '=' characters omitted (as permitted by Section 3.2) and trailing '=' characters omitted (as permitted by Section 3.2) and
without the inclusion of any line breaks, whitespace, or other without the inclusion of any line breaks, whitespace, or other
additional characters. (See Appendix A for notes on implementing additional characters. (See Appendix Appendix A for notes on
base64url encoding without padding.) implementing base64url encoding without padding.)
4. Protocol 4. Protocol
4.1. Client creates a code verifier 4.1. Client creates a code verifier
The client first creates a code verifier, "code_verifier", for each The client first creates a code verifier, "code_verifier", for each
OAuth 2.0 [RFC6749] Authorization Request, in the following manner: OAuth 2.0 [RFC6749] Authorization Request, in the following manner:
code_verifier = high entropy cryptographic random [US-ASCII] sequence code_verifier = high entropy cryptographic random [US-ASCII] sequence
using the url and filename safe Alphabet [A-Z] / [a-z] / [0-9] / "-" using the url and filename safe Alphabet [A-Z] / [a-z] / [0-9] / "-"
/ "_" from Sec 5 of RFC 4648 [RFC4648], with length less than 128 / "_" from Sec 5 of RFC 4648 [RFC4648], with length less than 128
characters. characters.
ABNF for "code_verifier" is as follows. ABNF for "code_verifier" is as follows.
code_verifier = 42*128unreserved code_verifier = 42*128unreserved
unreserved = [A-Z] / [a-z] / [0-9] / "-" / "_" unreserved = [A-Z] / [a-z] / [0-9] / "-" / "_"
NOTE: code verifier SHOULD have enough entropy to make it impractical NOTE: code verifier SHOULD have enough entropy to make it impractical
to guess the value. It is RECOMMENDED that the output of a suitable to guess the value. It is RECOMMENDED that the output of a suitable
random number generator be used to create a 32-octet sequence. The random number generator be used to create a 32-octet sequence. The
Octet sequence is then BASE64URL encoded to produce a 42-octet URL Octet sequence is then BASE64URL encoded to produce a 42-octet URL
safe string to use as the code verifier. safe string to use as the code verifier.
4.2. Client creates the code challenge 4.2. Client creates the code challenge
The client then creates a code challenge, "code_challenge", derived The client then creates a code challenge, "code_challenge", derived
from the "code_verifier" by using one of the following from the "code_verifier" by using one of the following
transformations on the "code_verifier": transformations on the "code_verifier":
plain "code_challenge" = "code_verifier" plain "code_challenge" = "code_verifier"
S256 "code_challenge" = BASE64URL(SHA256("code_verifier"))
S256 "code_challenge" = BASE64URL(SHA256("code_verifier"))
It is RECOMMENDED to use the S256 transformation when possible. It is RECOMMENDED to use the S256 transformation when possible.
ABNF for "code_challenge" is as follows. ABNF for "code_challenge" is as follows.
code_challenge = 42*128unreserved code_challenge = 42*128unreserved
unreserved = [A-Z] / [a-z] / [0-9] / "-" / "_" unreserved = [A-Z] / [a-z] / [0-9] / "-" / "_"
4.3. Client sends the code challenge with the authorization request 4.3. Client sends the code challenge with the authorization request
The client sends the code challenge as part of the OAuth 2.0 The client sends the code challenge as part of the OAuth 2.0
[RFC6749] Authorization Request (Section 4.1.1.) using the following [RFC6749] Authorization Request (Section 4.1.1.) using the following
additional parameters: additional parameters:
code_challenge REQUIRED. Code challenge. code_challenge REQUIRED. Code challenge.
code_challenge_method OPTIONAL, defaults to "plain". Code verifier code_challenge_method OPTIONAL, defaults to "plain". Code verifier
transformation method, "S256" or "plain". transformation method, "S256" or "plain".
4.4. Server returns the code 4.4. Server returns the code
When the server issues the "code" in the Authorization Response, it When the server issues the "code" in the Authorization Response, it
MUST associate the "code_challenge" and "code_challenge_method" MUST associate the "code_challenge" and "code_challenge_method"
values with the "code" so it can be verified later. values with the "code" so it can be verified later.
Typically, the "code_challenge" and "code_challenge_method" values Typically, the "code_challenge" and "code_challenge_method" values
are stored in encrypted form in the "code" itself, but could are stored in encrypted form in the "code" itself, but could
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in a form that other entities can extract. in a form that other entities can extract.
The exact method that the server uses to associate the The exact method that the server uses to associate the
"code_challenge" with the issued "code" is out of scope for this "code_challenge" with the issued "code" is out of scope for this
specification. specification.
4.4.1. Error Response 4.4.1. Error Response
If the server requires SPOP, and the client does not send the If the server requires SPOP, and the client does not send the
"code_challenge" in the request, the authorization endpoint MUST "code_challenge" in the request, the authorization endpoint MUST
return the authorization error response as described in 4.1.2.1. of return the authorization error response with "error" value set to
OAuth 2.0 [RFC6749] with "error" value set to "invalid_request" and "invalid_request" and "error_description" or "error_uri" whose
"error_description" or "error_uri" whose content explaining the content explaining the nature of error.
nature of error.
If the server supporting SPOP only supports "S256", and the client If the server supporting SPOP only supports "S256", and the client
requests plain transformation, the authorization endpoint MUST return requests plain transformation, the authorization endpoint MUST return
the authorization error response as described in 4.1.2.1. of OAuth the authorization error response with "error" value set to
2.0 [RFC6749] with "error" value set to "unsupported_spop_transform". "unsupported_spop_transform". The "error_description" or the
The "error_description" or the response of "error_uri" SHOULD explain response of "error_uri" SHOULD explain the nature of error, e.g.,
the nature of error, e.g., transform algorithm not supported. transform algorithm not supported.
If the client is capable of using "S256", it MUST use "S256", as If the client is capable of using "S256", it MUST use "S256", as
"S256" is MTI on the server. Clients MAY use plain only if they "S256" is MTI on the server. Clients MAY use plain only if they
cannot support "S256" for some technical reason and knows that the cannot support "S256" for some technical reason and knows that the
server supports "plain". server supports "plain".
4.5. Client sends the code and the secret to the token endpoint 4.5. Client sends the code and the secret to the token endpoint
Upon receipt of the "code", the client sends the Access Token Request Upon receipt of the "code", the client sends the Access Token Request
to the token endpoint. In addition to the parameters defined in to the token endpoint. In addition to the parameters defined in
OAuth 2.0 [RFC6749] Access Token Request (Section 4.1.3.), it sends OAuth 2.0 [RFC6749] Access Token Request (Section 4.1.3.), it sends
the following parameter: the following parameter:
code_verifier REQUIRED. Code verifier code_verifier REQUIRED. Code verifier
4.6. Server verifies code_verifier before returning the tokens 4.6. Server verifies code_verifier before returning the tokens
Upon receipt of the request at the Access Token endpoint, the server Upon receipt of the request at the Access Token endpoint, the server
verifies it by calculating the code challenge from received verifies it by calculating the code challenge from received
"code_verifier" and comparing it with the previously associated "code_verifier" and comparing it with the previously associated
"code_challenge", after first transforming it according to the "code_challenge", after first transforming it according to the
"code_challenge_method" method specified by the client. "code_challenge_method" method specified by the client.
If the "code_challenge_method" from 3.2 was "S256", the received If the "code_challenge_method" from Section 4.2 was "S256", the
"code_verifier" is first hashed with SHA-256 then compared to the received "code_verifier" is first hashed with SHA-256 then compared
base64url decoded "code_challenge". i.e., to the base64url decoded "code_challenge". i.e.,
SHA256("code_verifier" ) == BASE64URL-DECODE("code_challenge"). SHA256("code_verifier" ) == BASE64URL-DECODE("code_challenge").
If the "code_challenge_method" from 3.2 was "none", they are compared If the "code_challenge_method" from Section 4.2 was "plain", they are
directly. i.e., compared directly. i.e.,
"code_challenge" == "code_verifier". "code_challenge" == "code_verifier".
If the values are equal, the Access Token endpoint MUST continue If the values are equal, the Access Token endpoint MUST continue
processing as normal (as defined by OAuth 2.0 [RFC6749]). If the processing as normal (as defined by OAuth 2.0 [RFC6749]). If the
values are not equal, an error response indicating "invalid_grant" as values are not equal, an error response indicating "invalid_grant" as
described in section 5.2 of OAuth 2.0 [RFC6749] MUST be returned. described in section 5.2 of OAuth 2.0 [RFC6749] MUST be returned.
5. Compatibility 5. Compatibility
Server implementations of this specification MAY accept OAuth2.0 Server implementations of this specification MAY accept OAuth2.0
Clients that do not implement this extension. If the "code_verifier" Clients that do not implement this extension. If the "code_verifier"
is not received from the client in the Authorization Request, servers is not received from the client in the Authorization Request, servers
supporting backwards compatibility SHOULD revert to a normal OAuth supporting backwards compatibility SHOULD revert to a normal OAuth
2.0 [RFC6749] protocol. 2.0 [RFC6749] protocol.
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6. IANA Considerations 6. IANA Considerations
This specification makes a registration request as follows: This specification makes a registration request as follows:
6.1. OAuth Parameters Registry 6.1. OAuth Parameters Registry
This specification registers the following parameters in the IANA This specification registers the following parameters in the IANA
OAuth Parameters registry defined in OAuth 2.0 [RFC6749]. OAuth Parameters registry defined in OAuth 2.0 [RFC6749].
o Parameter name: code_verifier o Parameter name: code_verifier
o Parameter usage location: Access Token Request o Parameter usage location: Access Token Request
o Change controller: IESG o Change controller: IESG
o Specification document(s): this document o Specification document(s): this document
o Parameter name: code_challenge o Parameter name: code_challenge
o Parameter usage location: Authorization Request o Parameter usage location: Authorization Request
o Change controller: IESG o Change controller: IESG
o Specification document(s): this document o Specification document(s): this document
o Parameter name: code_challenge_method o Parameter name: code_challenge_method
o Parameter usage location: Authorization Request o Parameter usage location: Authorization Request
o Change controller: IESG o Change controller: IESG
o Specification document(s): this document o Specification document(s): this document
6.2. SPOP Code Challenge Method Registry
This specification establishes the SPOP Code Challenge Method
registry.
Additional code_challenge_method types for use with the authorization
endpoint are registered with a Specification Required ([RFC5226])
after a two-week review period on the oauth-ext-review@ietf.org
mailing list, on the advice of one or more Designated Experts.
However, to allow for the allocation of values prior to publication,
the Designated Expert(s) may approve registration once they are
satisfied that such a specification will be published.
Registration requests must be sent to the oauth-ext-review@ietf.org
mailing list for review and comment, with an appropriate subject
(e.g., "Request for SPOP code_challenge_method: example").
Within the review period, the Designated Expert(s) will either
approve or deny the registration request, communicating this decision
to the review list and IANA. Denials should include an explanation
and, if applicable, suggestions as to how to make the request
successful.
IANA must only accept registry updates from the Designated Expert(s)
and should direct all requests for registration to the review mailing
list.
6.2.1. Registration Template
Code Challenge Method Parameter Name:
The name requested (e.g., "example"). Because a core goal of this
specification is for the resulting representations to be compact,
it is RECOMMENDED that the name be short -- not to exceed 8
characters without a compelling reason to do so. This name is
case-sensitive. Names may not match other registered names in a
case-insensitive manner unless the Designated Expert(s) state that
there is a compelling reason to allow an exception in this
particular case.
Change Controller:
For Standards Track RFCs, state "IESG". For others, give the name
of the responsible party. Other details (e.g., postal address,
email address, home page URI) may also be included.
Specification Document(s):
Reference to the document(s) that specify the parameter,
preferably including URI(s) that can be used to retrieve copies of
the document(s). An indication of the relevant sections may also
be included but is not required.
6.2.2. Initial Registry Contents
This specification registers the Code Challenge Method Parameter
names defined in Section 4.2 in this registry.
o Code Challenge Method Parameter Name: "plain"
o Change Controller: IESG
o Specification Document(s): Section 4.2 of [[ this document ]]
o Code Challenge Method Parameter Name: "S256"
o Change Controller: IESG
o Specification Document(s): Section 4.2 of [[ this document ]]
7. Security Considerations 7. Security Considerations
7.1. Entropy of the code verifier 7.1. Entropy of the code verifier
The security model relies on the fact that the code verifier is not The security model relies on the fact that the code verifier is not
learned or guessed by the attacker. It is vitally important to learned or guessed by the attacker. It is vitally important to
adhere to this principle. As such, the code verifier has to be adhere to this principle. As such, the code verifier has to be
created in such a manner that it is cryptographically random and has created in such a manner that it is cryptographically random and has
high entropy that it is not practical for the attacker to guess. It high entropy that it is not practical for the attacker to guess. It
is RECOMMENDED that the output of a suitable random number generator is RECOMMENDED that the output of a suitable random number generator
skipping to change at page 9, line 44 skipping to change at page 10, line 4
All the OAuth security analysis presented in [RFC6819] applies so All the OAuth security analysis presented in [RFC6819] applies so
readers SHOULD carefully follow it. readers SHOULD carefully follow it.
8. Acknowledgements 8. Acknowledgements
The initial draft of this specification was created by the OpenID AB/ The initial draft of this specification was created by the OpenID AB/
Connect Working Group of the OpenID Foundation, most notably by the Connect Working Group of the OpenID Foundation, most notably by the
following people: following people:
o Naveen Agarwal, Google o Naveen Agarwal, Google
o Dirk Balfanz, Google o Dirk Balfanz, Google
o Sergey Beryozkin o Sergey Beryozkin
o John Bradley, Ping Identity o John Bradley, Ping Identity
o Brian Campbell, Ping Identity o Brian Campbell, Ping Identity
o William Denniss, Google o William Denniss, Google
o Eduardo Gueiros, Jive Communications o Eduardo Gueiros, Jive Communications
o Phil Hunt, Oracle o Phil Hunt, Oracle
o Ryo Ito, mixi o Ryo Ito, mixi
o Michael B. Jones, Microsoft
o Michael B. Jones, Microsoft
o Torsten Lodderstedt, Deutsche Telekom o Torsten Lodderstedt, Deutsche Telekom
o Breno de Medeiros, Google o Breno de Medeiros, Google
o Prateek Mishra, Oracle o Prateek Mishra, Oracle
o Anthony Nadalin, Microsoft o Anthony Nadalin, Microsoft
o Axel Nenker, Deutsche Telekom o Axel Nenker, Deutsche Telekom
o Nat Sakimura, Nomura Research Institute o Nat Sakimura, Nomura Research Institute
9. Revision History 9. Revision History
-05
o Added IANA registry for code_challenge_method + fixed some broken
internal references.
-04 -04
o Added error response to authorization response. o Added error response to authorization response.
-03 -03
o Added an abstract protocol diagram and explanation o Added an abstract protocol diagram and explanation
-02 -02
skipping to change at page 11, line 36 skipping to change at page 11, line 28
6749, October 2012. 6749, October 2012.
[US-ASCII] [US-ASCII]
American National Standards Institute, "Coded Character American National Standards Institute, "Coded Character
Set -- 7-bit American Standard Code for Information Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986. Interchange", ANSI X3.4, 1986.
10.2. Informative References 10.2. Informative References
[OpenID.Discovery] [OpenID.Discovery]
Sakimura, N., Bradley, J., Jones, M., and E. Jay, "OpenID Sakimura, N., Bradley, J., Jones, M.B. and E. Jay, "OpenID
Connect Discovery 1.0", February 2014. Connect Discovery 1.0", February 2014.
[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,
January 2013. January 2013.
Appendix A. Notes on implementing base64url encoding without padding Appendix A. Notes on implementing base64url encoding without padding
This appendix describes how to implement base64url encoding and This appendix describes how to implement base64url encoding and
decoding functions without padding based upon standard base64 decoding functions without padding based upon standard base64
encoding and decoding functions that do use padding. encoding and decoding functions that do use padding.
To be concrete, example C# code implementing these functions is shown To be concrete, example C# code implementing these functions is shown
skipping to change at page 13, line 4 skipping to change at page 12, line 48
An example correspondence between unencoded and encoded values An example correspondence between unencoded and encoded values
follows. The octet sequence below encodes into the string below, follows. The octet sequence below encodes into the string below,
which when decoded, reproduces the octet sequence. which when decoded, reproduces the octet sequence.
3 236 255 224 193 3 236 255 224 193
A-z_4ME A-z_4ME
Authors' Addresses Authors' Addresses
Nat Sakimura (editor)
Nat Sakimura, editor
Nomura Research Institute Nomura Research Institute
1-6-5 Marunouchi, Marunouchi Kitaguchi Bldg. 1-6-5 Marunouchi, Marunouchi Kitaguchi Bldg.
Chiyoda-ku, Tokyo 100-0005 Chiyoda-ku, Tokyo 100-0005
Japan Japan
Phone: +81-3-5533-2111 Phone: +81-3-5533-2111
Email: n-sakimura@nri.co.jp Email: n-sakimura@nri.co.jp
URI: http://nat.sakimura.org/ URI: http://nat.sakimura.org/
John Bradley John Bradley
Ping Identity Ping Identity
Casilla 177, Sucursal Talagante Casilla 177, Sucursal Talagante
Talagante, RM Talagante, RM
Chile Chile
Phone: +44 20 8133 3718 Phone: +44 20 8133 3718
Email: ve7jtb@ve7jtb.com Email: ve7jtb@ve7jtb.com
URI: http://www.thread-safe.com/ URI: http://www.thread-safe.com/
skipping to change at page 13, line 27 skipping to change at page 13, line 17
Talagante, RM Talagante, RM
Chile Chile
Phone: +44 20 8133 3718 Phone: +44 20 8133 3718
Email: ve7jtb@ve7jtb.com Email: ve7jtb@ve7jtb.com
URI: http://www.thread-safe.com/ URI: http://www.thread-safe.com/
Naveen Agarwal Naveen Agarwal
Google Google
1600 Amphitheatre Pkwy 1600 Amphitheatre Pkwy
Mountain View, CA 94043 Mountain View, CA 94043
USA USA
Phone: +1 650-253-0000 Phone: +1 650-253-0000
Email: naa@google.com Email: naa@google.com
URI: http://google.com/ URI: http://google.com/
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