Subject: Protocol Action: 'RADIUS Extension for Digest Authentication' to Proposed Standard

From: The IESG <[email-masked]>
Date: Thu, 23 Aug 2007 16:17:36 -0400

The IESG has approved the following document:

- 'RADIUS Extension for Digest Authentication '
   <draft-ietf-radext-rfc4590bis-02.txt> as a Proposed Standard

This document is the product of the RADIUS EXTensions Working Group. 

The IESG contact persons are Dan Romascanu and Ron Bonica.

A URL of this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-radext-rfc4590bis-02.txt

Technical Summary
 
   This document defines an extension to the Remote Authentication Dial-
   In User Service (RADIUS) protocol to enable support of Digest
   Authentication, for use with HTTP-style protocols like the Session
   Initiation Protocol (SIP) and HTTP.
 
Working Group Summary
 
   Working Group discussion largely centered on whether the issues
   identified in RFC 4590 could be fixed via an errata or whether
   a new RFC was required.  Due to conflicts between the RFC 4590 text
   and the parameters allocated by IANA, it was decided that a new
   RFC would be needed, so as to avoid potential interoperability
   problems.

Protocol Quality
 
This document is needed to address a problem in the IANA allocations for
Digest Authentication as well as several errata that were found after the
publication of RFC 4590.  This document is believed to address all issues
raised since the publication of RFC 4590. The document was reviewed by Dan
Romascanu on behalf of the IESG. 

Note to RFC Editor
 
 RFC Editor,
 Please replace Appendix A with the text below: 

  This is an example selected from the traffic between a softphone (A),
  a Proxy Server (B), and an example.com RADIUS server (C).  The
  communication between the Proxy Server and a SIP Public Switched
  Telephone Network (PSTN) gateway is omitted for brevity.  The SIP
  messages are not shown completely.

  The password of user '12345678' is 'secret'. The shared secret
  between RADIUS client and server is 'secret'. To ease testing,
  only the last byte of the RADIUS authenticator changes between
  requests. In a real implementation, this would be a serious flaw.

  A->B

     INVITE sip:[email-masked] SIP/2.0
     From: <sip:[email-masked]>
     To: <sip:[email-masked]>

  B->A

     SIP/2.0 100 Trying

  B->C

     Code = Access-Request (1)
     Packet identifier = 0x7c (124)
     Length = 97
     Authenticator = F5E55840E324AA49D216D9DBD069807C
     NAS-IP-Address = 192.0.2.38
     NAS-Port = 5
     User-Name = 12345678
     Digest-Method = INVITE
     Digest-URI = sip:[email-masked]
     Message-Authenticator = 7600D5B0BDC33987A60D5C6167B28B3B

  C->B

     Code = Access-challenge (11)
     Packet identifier = 0x7c (124)
     Length = 72
     Authenticator = EBE20199C26EFEAD69BF8AB0E786CA4D
     Digest-Nonce = 3bada1a0
     Digest-Realm = example.com
     Digest-Qop = auth
     Digest-Algorithm = MD5
     Message-Authenticator = 5DA18ED3BBC9513DCBDE0A37F51B7DE3

  B->A

     SIP/2.0 407 Proxy Authentication Required
     Proxy-Authenticate: Digest realm="example.com"
          ,nonce="3bada1a0",qop=auth,algorithm=MD5
     Content-Length: 0

  A->B

     ACK sip:[email-masked] SIP/2.0

  A->B

     INVITE sip:[email-masked] SIP/2.0
     Proxy-Authorization: Digest algorithm="md5",nonce="3bada1a0"
          ,realm="example.com"
          ,response="7679b84a560835846ec553174dbabb69"
          ,uri="sip:[email-masked]",username="12345678"
          ,qop=auth,algorithm=MD5
          ,cnonce="56593a80,nc="00000001"

     From: <sip:[email-masked]>
     To: <sip:[email-masked]>

  B->C

     Code = Access-Request (1)
     Packet identifier = 0x7d (125)
     Length = 221
     Authenticator = F5E55840E324AA49D216D9DBD069807D
     NAS-IP-Address = 192.0.2.38
     NAS-Port = 5
     User-Name = 12345678
     Digest-Method = INVITE
     Digest-URI = sip:[email-masked]
     Digest-Realm = example.com
     Digest-Qop = auth
     Digest-Algorithm = MD5
     Digest-CNonce = 56593a80
     Digest-Nonce = 3bada1a0
     Digest-Nonce-Count = 00000001
     Digest-Response = 7679b84a560835846ec553174dbabb69
     Digest-Username = 12345678
     SIP-AOR = sip:[email-masked]
     Message-Authenticator = BD037498E8385878A46ECF4D5F8D2B48

  C->B

     Code = Access-Accept (2)
     Packet identifier = 0x7d (125)
     Length = 72
     Authenticator = 36E1201AD4377664E720184CE7B3D8C6
     Digest-Response-Auth = 3792d3109224eb67213659e2d789f10d
     Message-Authenticator = 9B79B410CEBD335176DAEB24735DCF64

  B->A

     SIP/2.0 180 Ringing

  B->A

     SIP/2.0 200 OK

  A->B

     ACK sip:[email-masked] SIP/2.0

  A second example shows the traffic between a web browser (A), web
  server (B), and a RADIUS server (C).

  A->B

     GET /index.html HTTP/1.1

  B->C
     Code = Access-Request (1)
     Packet identifier = 0x7e (126)
     Length = 68
     Authenticator = F5E55840E324AA49D216D9DBD069807E
     NAS-IP-Address = 192.0.2.38
     NAS-Port = 5
     Digest-Method = GET
     Digest-URI = /index.html
     Message-Authenticator = 690BFC95E88DF3B185F15CD78E469992

  C->B

     Code = Access-challenge (11)
     Packet identifier = 0x7e (126)
     Length = 72
     Authenticator = 2EE5EB01C02C773B6C6EC8515F565E8E
     Digest-Nonce = a3086ac8
     Digest-Realm = example.com
     Digest-Qop = auth
     Digest-Algorithm = MD5
     Message-Authenticator = 646DB2B0AF9E72FFF2CF7FEB33C4952A

  B->A

     HTTP/1.1 401 Authentication Required
     WWW-Authenticate: Digest realm="example.com",
         nonce="a3086ac8",qop=auth,algorithm=MD5
     Content-Length: 0

  A->B

     GET /index.html HTTP/1.1
     Authorization: Digest algorithm=MD5,qop=auth,nonce="a3086ac8"
          ,nc="00000001",cnonce="56593a78"
          ,realm="example.com"
          ,response="ba623217b5ec024d30c4aaef9d8494de"
          ,uri="/index.html",username="12345678"

  B->C

     Code = Access-Request (1)
     Packet identifier = 0x7f (127)
     Length = 176
     Authenticator = F5E55840E324AA49D216D9DBD069807F
     NAS-IP-Address = 192.0.2.38
     NAS-Port = 5
     User-Name = 12345678
     Digest-Method = GET
     Digest-URI = /index.html
     Digest-Realm = example.com
     Digest-Qop = auth
     Digest-Algorithm = MD5
     Digest-CNonce = 56593a80
     Digest-Nonce = a3086ac8
     Digest-Nonce-Count = 00000001
     Digest-Response = ba623217b5ec024d30c4aaef9d8494de
     Digest-Username = 12345678
     Message-Authenticator = C360BFCEDFFBCE893469E802013DA5AA

  C->B

     Code = Access-Accept (2)
     Packet identifier = 0x7f (127)
     Length = 72
     Authenticator = F1ECAC22D3C88E0260B287FA35595F80
     Digest-Response-Auth = 29624e0bee4342994d041d07f7bcd44c
     Message-Authenticator = 956312EC57AF51ABC4F6965270F34982

  B->A

     HTTP/1.1 200 OK
     ...

     <html>
     ...

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