Secure Password Ciphersuites for Transport Layer Security (TLS)
RFC 8492

Document Type RFC - Informational (February 2019; Errata)
Last updated 2019-05-21
Replaces draft-ietf-tls-pwd
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Independent Submission                                   D. Harkins, Ed.
Request for Comments: 8492                                 HP Enterprise
Category: Informational                                    February 2019
ISSN: 2070-1721

    Secure Password Ciphersuites for Transport Layer Security (TLS)

Abstract

   This memo defines several new ciphersuites for the Transport Layer
   Security (TLS) protocol to support certificateless, secure
   authentication using only a simple, low-entropy password.  The
   exchange is called "TLS-PWD".  The ciphersuites are all based on an
   authentication and key exchange protocol, named "dragonfly", that is
   resistant to offline dictionary attacks.

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 candidates for any level of Internet Standard;
   see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8492.

Copyright Notice

   Copyright (c) 2019 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
   (https://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.

Harkins                       Informational                     [Page 1]
RFC 8492                      TLS Password                 February 2019

Table of Contents

   1. Introduction and Motivation .....................................3
      1.1. The Case for Certificateless Authentication ................3
      1.2. Resistance to Dictionary Attacks ...........................3
   2. Key Words .......................................................4
   3. Notation and Background .........................................4
      3.1. Notation ...................................................4
      3.2. Discrete Logarithm Cryptography ............................5
           3.2.1. Elliptic Curve Cryptography .........................5
           3.2.2. Finite Field Cryptography ...........................7
      3.3. Instantiating the Random Function ..........................8
      3.4. Passwords ..................................................8
      3.5. Assumptions ................................................9
   4. Specification of the TLS-PWD Handshake .........................10
      4.1. TLS-PWD Pre-TLS 1.3 .......................................10
      4.2. TLS-PWD in TLS 1.3 ........................................11
      4.3. Protecting the Username ...................................11
           4.3.1. Construction of a Protected Username ...............12
           4.3.2. Recovery of a Protected Username ...................13
      4.4. Fixing the Password Element ...............................14
           4.4.1. Computing an ECC Password Element ..................16
           4.4.2. Computing an FFC Password Element ..................18
           4.4.3. Password Naming ....................................19
           4.4.4. Generating TLS-PWD Commit ..........................20
      4.5. Changes to Handshake Message Contents .....................20
           4.5.1. Pre-1.3 TLS ........................................20
                  4.5.1.1. ClientHello Changes .......................20
                  4.5.1.2. ServerKeyExchange Changes .................21
                  4.5.1.3. ClientKeyExchange Changes .................23
           4.5.2. TLS 1.3 ............................................24
                  4.5.2.1. TLS 1.3 KeyShare ..........................24
                  4.5.2.2. ClientHello Changes .......................24
                  4.5.2.3. ServerHello Changes .......................25
                  4.5.2.4. HelloRetryRequest Changes .................25
      4.6. Computing the Shared Secret ...............................26
   5. Ciphersuite Definition .........................................26
   6. IANA Considerations ............................................27
   7. Security Considerations ........................................27
   8. Human Rights Considerations ....................................30
   9. Implementation Considerations ..................................31
   10. References ....................................................32
      10.1. Normative References .....................................32
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