Extensions to Salted Challenge Response (SCRAM) for 2 factor authentication
draft-melnikov-scram-2fa-02

• Status
• IESG evaluation record
• IESG writeups
• Email expansions
• History

• Versions
• 00
• 01
• 02

Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                        October 29, 2020
Expires: May 2, 2021

      Extensions to Salted Challenge Response (SCRAM) for 2 factor
                             authentication
                      draft-melnikov-scram-2fa-02

Abstract

   This specification describes an extension to family of Simple
   Authentication and Security Layer (SASL; RFC 4422) authentication
   mechanisms called the Salted Challenge Response Authentication
   Mechanism (SCRAM), which provides support for 2 factor
   authentication.

   This specification also gives an example how TOTP (RFC 6238) can be
   used as the second factor.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   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 https://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 May 2, 2021.

Copyright Notice

   Copyright (c) 2020 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

Melnikov                   Expires May 2, 2021                  [Page 1]
Internet-Draft            SCRAM 2FA extensions              October 2020

   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   2
   2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.2.  Notation  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  SCRAM Extension for 2FA . . . . . . . . . . . . . . . . . . .   3
   4.  Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Use of TOTP with SCRAM  . . . . . . . . . . . . . . . . . . .   4
   6.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   7.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   SCRAM [RFC5802] is a password based SASL [RFC4422] authentication
   mechanism that provides (among other things) mutual authentication
   and binding to an external security layer such as TLS.

   Two-factor authentication (2FA) is a way to add additional security
   to an authentication exchange.  The first "factor" is a password.
   The second "factor" is a verification code retrieved from an
   application on a mobile device or computer.  2FA is conceptually
   similar to a security token device that banks in some countries
   require for online banking.  Other names for 2FA systems include OTP
   (one-time password) and TOTP (Time-based One-time Password algorithm,
   such as [RFC6238]).

   This specification describes an extension to SCRAM to provide 2
   factor authentication.  SCRAM already relies on passwords for
   authentication.  This document specifies how second "factors" can be
   incorporated into SCRAM authentication.

2.  Conventions Used in This Document

   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].

Melnikov                   Expires May 2, 2021                  [Page 2]
Internet-Draft            SCRAM 2FA extensions              October 2020

   Formal syntax is defined by [RFC5234] including the core rules
   defined in Appendix B of [RFC5234].

   Example lines prefaced by "C:" are sent by the client and ones
   prefaced by "S:" by the server.  If a single "C:" or "S:" label