Network Working Group A. Melnikov Internet Draft Isode Limited Document: draft-melnikov-sasl-auxprop-attrs-00.txt April 2004 Expires in six months An LDAP Schema for CMU SASL auxiliary properties plugins Status of this Memo This document is an Internet Draft and is in full conformance with all provisions of Section 10 of RFC 2026. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its Areas, and its Working Groups. Note that other groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as ``work in progress''. The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. A revised version of this draft document will be submitted to the RFC editor as a Draft Standard for the Internet Community. Discussion and suggestions for improvement are requested. Distribution of this draft is unlimited. A. Melnikov FORMFEED[Page i]
Internet DRAFT SASL 2 April 2004 Abstract The CMU SASL implementation of the RFC 2222 defines an API for auxiliary properties (auxprop) plugins. Auxprop plugins can store properties. A property can be a user password in cleartext or in a hashed form used by a particular SASL mechanism, or any other information associated with the user. This document describes a schema for the storage of auxprop properties in an LDAP directory server. 1. Conventions used in this document The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY" in this document are to be interpreted as defined in "Key words for use in RFCs to Indicate Requirement Levels" [KEYWORDS]. <<1.3.6.1.4.1.3.8 - "ldapResources" under CMU node. 1.3.6.1.4.1.3.8.1 - cmuSaslAuxprop 1.3.6.1.4.1.3.8.1.0 - Syntaxes 1.3.6.1.4.1.3.8.1.1 - Attributes types 1.3.6.1.4.1.3.8.1.2 - Object classes >> 2. SASL related Attribute Types This document defines the attribute types cmusaslsecretCRAM-MD5, cmusaslsecretDIGEST-MD5, cmusaslsecretOTP and cmusaslsecretSRP. Their definition is provided below. ( 1.3.6.1.4.1.3.8.1.1.1 NAME 'cmusaslsecretCRAM-MD5' DESC 'Prehashed password as described in CRAM-MD5' EQUALITY octetStringMatch SINGLE-VALUE SYNTAX 1.3.6.1.4.1.1466.115.121.1.40{32} ) cmusaslsecretCRAM-MD5 attribute contains the binary representation of the following C structure: typedef struct HMAC_MD5_STATE_s { UINT4 ipad_state[4]; UINT4 opad_state[4]; A. Melnikov FORMFEED[Page 2]
Internet DRAFT SASL 2 April 2004 } HMAC_MD5_STATE; i.e. 16 bytes (4 element array of 32bit integers, each element in network byte order) of ipad is followed by 16 bytes (4 element array of 32bit integers, each element in network byte order) of opad. ipad and opad are calculated as defined in [SASL-CRAM]. ( 1.3.6.1.4.1.3.8.1.1.2 NAME 'cmusaslsecretDIGEST-MD5' DESC 'Shared secret for DIGEST-MD5' EQUALITY octetStringMatch SINGLE-VALUE SYNTAX 1.3.6.1.4.1.1466.115.121.1.40{16} ) The cmusaslsecretDIGEST-MD5 attribute contains the binary representation of SS (16-octets) as defined in section 2.1.2.1 of [SASL-DIGEST]: SS = H( { unq(username-value), ":", unq(realm-value), ":", passwd } ) ( 1.3.6.1.4.1.3.8.1.1.3 NAME 'cmusaslsecretOTP' DESC 'OTP secret' EQUALITY octetStringMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.40 ) The cmusaslsecretOTP attribute is a tab separated octet string that contains information relevant for OTP [SASL-OTP] authentication. The syntax of the string is as follows: <alg> \t <seq> \t <seed> \t <otp> \t <timeout> where \t is the horizontal tab character (%x09), <alg> - name of the hashing algorithm as described in [SASL-OTP]; <otp> - 16 hex digits (in lowercase) of the 8-byte OTP hash; <seq> - 4 digit unsigned integer that specifies how many times the user is allowed to log in using the password before it has to change it. This value is decremented each time the user has successfully authenticated; <seed> - random string that doesn't contain \t (<<and no NULs?>>) <timeout> 20 digit unsigned integer, the time since the Epoch (00:00:00 UTC, January 1, 1970), measured in seconds. It defines the time when the record lock expires. This value is used to lock A. Melnikov FORMFEED[Page 3]
Internet DRAFT SASL 2 April 2004 the record, as OTP doesn't allow for simultaneous authentication by the same user. This attribute is multivalued. For example, it may contain multiple OTP hashes for different hashing algorithms. ( 1.3.6.1.4.1.3.8.1.1.4 NAME 'cmusaslsecretSRP' DESC 'base64 encoded SRP secret' EQUALITY octetStringMatch SYNTAX 1.3.6.1.4.1.1466.115.121.1.40 ) This is the base64 encoding of the following data described in [SASL- SRP]: { utf8(mda) mpi(v) os(salt) } where mda - message digest algorithm name as defined in [SASL-SRP] v - password verifier (<<See: RFC 2945>>) salt - a random string, 1 to 255 octets in length This attribute is multivalued. For example, it may contain data for multiple message digest algorithms. <<cmusaslsecretPLAIN is deprecated in favor of userPassword>> 3. Object Classes This document defines the following object class: ( 1.3.6.1.4.1.3.8.1.2.1 NAME 'cmuSaslUser' SUP top AUXILIARY MAY ( userPassword $ cmusaslsecretCRAM-MD5 $ cmusaslsecretDIGEST-MD5 $ cmusaslsecretOTP $ cmusaslsecretSRP) ) The cmusaslsecretCRAM-MD5, cmusaslsecretDIGEST-MD5, cmusaslsecretOTP and cmusaslsecretSRP attribute types are described in section 2 of this document. The userPassword attribute type is defined in [RFC2256]. A. Melnikov FORMFEED[Page 4]
Internet DRAFT SASL 2 April 2004 4. Security considerations <<Rant about userPassword>> 5. References 5.1. Normative References [KEYWORDS] Bradner, "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997 [RFC2256] Wahl, A., "A Summary of the X.500(96) User Schema for use with LDAPv3", RFC 2256, December 1997 [SASL-CRAM] Nerenberg, L. (Editor), "The CRAM-MD5 SASL Mechanism", work in progress, draft-ietf-sasl-crammd5-XX.txt, replaces RFC 2195 [KEYED-MD5] Krawczyk, Bellare, Canetti, "HMAC: Keyed-Hashing for Message Authentication", RFC 2104, IBM and UCSD, February 1997. [SASL-DIGEST] Leach, P., Newman, C., Melnikov, A., "Using Digest Authentication as a SASL Mechanism", work in progress, draft-ietf- sasl-rfc2831bis-XX.txt, replaces RFC 2831 [SASL-OTP] Newman, C., "The One-Time-Password SASL Mechanism", RFC 2444, October 1998 [SASL-SRP] Burdis, K.R., Naffah, R., "Secure Remote Password SASL Mechanism", work in progress, draft-burdis-cat-srp-sasl-XX.txt 5.2. Informative References 6. Author's Address Alexey Melnikov Isode Limited 5 Castle Business Village 36 Station Road Hampton, Middlesex TW12 2BX, United Kingdom Email: Alexey.Melnikov@isode.com URI: http://www.melnikov.ca/ A. Melnikov FORMFEED[Page 5]
Internet DRAFT SASL 2 April 2004 7. Acknowledgments The author of the document would like to thank Howard Chu for reminding that this document has to be written; to Chris Ridd, Damy Mahl and Rob Siemborski for comments and suggestions to this document; to Ken Murchison for designing the OTP and SRP secret formats. 8. Full Copyright Statement Copyright (C) The Internet Society (2004). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. 9. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in A. Melnikov FORMFEED[Page 6]
Internet DRAFT SASL 2 April 2004 this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. A. Melnikov FORMFEED[Page 7]
Internet DRAFT SASL 2 April 2004 Status of this Memo .......................................... i Abstract ..................................................... 2 1. Conventions used in this document ...................... 2 2. SASL related Attribute Types ........................... 2 3. Object Classes ......................................... 4 4. Security considerations ................................. 5 5. References ............................................. 5 5.1. Normative References ................................... 5 5.2. Informative References ................................. 5 6. Author's Address ........................................ 5 7. Acknowledgments ......................................... 6 8. Full Copyright Statement ................................ 6 9. Intellectual Property ................................... 6 A. Melnikov FORMFEED[Page ii]