Password-Authenticated Key (PAK) Diffie-Hellman Exchange
RFC 5683
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RFC - Informational
(February 2010; No errata)
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Last updated |
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2015-10-14
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ISE
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plain text
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bibtex
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(None)
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Unknown
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No shepherd assigned
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IESG state |
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RFC 5683 (Informational)
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Responsible AD |
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Tim Polk
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rfc-editor@rfc-editor.org
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Independent Submission A. Brusilovsky
Request for Comments: 5683 I. Faynberg
Category: Informational Z. Zeltsan
ISSN: 2070-1721 Alcatel-Lucent
S. Patel
Google, Inc.
February 2010
Password-Authenticated Key (PAK) Diffie-Hellman Exchange
Abstract
This document proposes to add mutual authentication, based on a
human-memorizable password, to the basic, unauthenticated Diffie-
Hellman key exchange. The proposed algorithm is called the Password-
Authenticated Key (PAK) exchange. PAK allows two parties to
authenticate themselves while performing the Diffie-Hellman exchange.
The protocol is secure against all passive and active attacks. In
particular, it does not allow either type of attacker to obtain any
information that would enable an offline dictionary attack on the
password. PAK provides Forward Secrecy.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This is a contribution to the RFC Series, independently of any other
RFC stream. The RFC Editor has chosen to publish this document at
its discretion and makes no statement about its value for
implementation or deployment. Documents approved for publication by
the RFC Editor are not a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5683.
Brusilovsky, et al. Informational [Page 1]
RFC 5683 PAK Diffie-Hellman Exchange February 2010
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http:trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document.
Table of Contents
1. Introduction ....................................................3
2. Conventions .....................................................3
3. Password-Authenticated Key Exchange .............................4
4. Selection of Parameters .........................................5
4.1. General Considerations .....................................5
4.2. Over-the-Air Service Provisioning (OTASP) and Wireless
Local Area Network (WLAN) Diffie-Hellman Parameters and
Key Expansion Functions ....................................5
5. Security Considerations .........................................7
6. Acknowledgments .................................................8
7. References ......................................................8
7.1. Normative References .......................................8
7.2. Informative References .....................................8
Brusilovsky, et al. Informational [Page 2]
RFC 5683 PAK Diffie-Hellman Exchange February 2010
1. Introduction
PAK has the following advantages:
- It provides a secure, authenticated key-exchange protocol.
- It is secure against offline dictionary attacks when passwords are
used.
- It ensures Forward Secrecy.
- It has been proven to be as secure as the Diffie-Hellman solution.
The PAK protocol ([BMP00], [MP05], [X.1035]) has been proven to be as
secure as the Diffie-Hellman ([RFC2631], [DH76]) in the random oracle
model [BR93]. That is, PAK retains its security when used with low-
entropy passwords. Therefore, it can be seamlessly integrated into
existing applications, requiring secure authentication based on such
low-entropy shared secrets.
2. Conventions
- A is an identity of Alice.
- B is an identity of Bob.
- Ra is a secret random exponent selected by A.
- Rb is a secret random exponent selected by B.
- Xab denotes a value (X presumably computed by A) as derived by B.
- Yba denotes a value (Y presumably computed by B) as derived by A.
- A mod b denotes the least non-negative remainder when a is divided
by b.
- Hi(u) denotes an agreed-on function (e.g., based on SHA-1,
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