Network Working Group G. Zorn Internet-Draft Network Zen Intended status: Standards Track March 7, 2011 Expires: September 8, 2011 A Method for Changing Cleartext Passwords in the Extensible Authentication Protocol draft-zorn-emu-eap-pwc-00 Abstract The Extensible Authentication Protocol (EAP) provides support for multiple authentication methods. One such method is Generic Token Card (EAP-GTC) which, despite its name, is commonly used to support authentication using cleartext passwords in tunneled EAP methods. EAP-GTC does not provide the ability to change a password (for example, an expired password), however. This document defines the PassWord Change EAP method (EAP-PWC) in order to fill that void in functionality. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to format it for publication as an RFC or to translate it into languages other than English. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 8, 2011. Copyright Notice Copyright (c) 2011 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 Zorn Expires September 8, 2011 [Page 1] Internet-Draft EAP-PWC March 2011 (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. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3 3. EAP-PWC . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . . 5 Zorn Expires September 8, 2011 [Page 2] Internet-Draft EAP-PWC March 2011 1. Introduction The Generic Token Card EAP method (EAP-GTC) [RFC3748] is commonly used to support authentication using cleartext passwords in tunneled EAP methods. However, EAP-GTC does not provide the ability to change a password (for example, one which is about to expire). This document defines the PassWord Change EAP method (EAP-PWC) in order to fill that void in EAP functionality. 2. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. EAP-PWC Description If the EAP authenticator determines that the password should be changed as a result of the evaluation of the EAP/Identity response, it SHOULD send an EAP-PWC/Request to the peer. The Request contains a pair of displayable messages separated by the NUL character (0x00) and the Response contains the old and new passwords, also separated by a single NUL character. A Response MUST be sent in reply to the Request. The Response MUST be of Type (PWC), Nak (Type 3), or Expanded Nak (Type 254) [RFC3748]. The Nak Response indicates the peer's desired authentication Type(s). The EAP-PWC method MUST NOT be used to provide support for cleartext password change in the absence of a protected tunnel with server authentication (e.g., TEAM [I-D.zorn-emu-team]). Type Type-Data The Type-Data field in the Request contains a displayable message concatenated with a single NUL character concatenated with a displayable message. Each of the messages MUST be individually processed according to the rules of the [RFC4013] profile of [RFC3454] before the concatenation is performed. The messages SHALL be considered to be "stored strings" per [RFC3454], and unassigned code points are therefore prohibited. The output SHALL be the binary representation of the processed UTF-8 character string. Prohibited output and unassigned codepoints encountered Zorn Expires September 8, 2011 [Page 3] Internet-Draft EAP-PWC March 2011 in SASLprep pre-processing SHALL cause a failure of pre- processing, and the output SHALL NOT be used with EAP-PWC. The Type-Data field in the Response contains the old password concatenated with a single NUL character concatenated with the new password. Each of the strings MUST be individually processed according to the rules of the [RFC4013] profile of [RFC3454] before the concatenation is performed. The passwords SHALL be considered to be "stored strings" per [RFC3454], and unassigned code points are therefore prohibited. The output SHALL be the binary representation of the processed UTF-8 character string. Prohibited output and unassigned codepoints encountered in SASLprep pre-processing SHALL cause a failure of pre-processing, and the output SHALL NOT be used with EAP-PWC. Security Claims Auth. mechanism: Cleartext password Ciphersuite negotiation: No Mutual authentication: No Integrity protection: No Replay protection: No Confidentiality: No Key derivation: No Key strength: N/A Dictionary attack prot.: No Fast reconnect: No Crypto binding: N/A Session independence: N/A Fragmentation: No Channel binding: No 4. Security Considerations The EAP-PWC method MUST NOT be used in the absence of a cryptographically protected tunnel with server authentication. 5. IANA Considerations This memo requires IANA to allocate a new EAP method type for EAP- PWC. The placeholder indicated by in Section 3 above shall be replaced by the new EAP method type upon assignment by IANA. 6. References Zorn Expires September 8, 2011 [Page 4] Internet-Draft EAP-PWC March 2011 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3454] Hoffman, P. and M. Blanchet, "Preparation of Internationalized Strings ("stringprep")", RFC 3454, December 2002. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, "Extensible Authentication Protocol (EAP)", RFC 3748, June 2004. [RFC4013] Zeilenga, K., "SASLprep: Stringprep Profile for User Names and Passwords", RFC 4013, February 2005. 6.2. Informative References [I-D.zorn-emu-team] Zorn, G., Wu, W., and D. Harkins, "The Tunneled Extensible Authentication Protocol Method (TEAM)", draft-zorn-emu-team-01 (work in progress), October 2010. Author's Address Glen Zorn Network Zen 227/358 Thanon Sanphawut Bang Na, Bangkok 10260 Thailand Phone: +66 (0) 87-040-4617 EMail: gwz@net-zen.net Zorn Expires September 8, 2011 [Page 5]