TOTP: Time-Based One-Time Password Algorithm
RFC 6238
| Document | Type |
RFC - Informational
(May 2011; Errata)
Was draft-mraihi-totp-timebased (individual in sec area)
|
|
|---|---|---|---|
| Last updated | 2020-01-21 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized with errata bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 6238 (Informational) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | Sean Turner | ||
| IESG note | Hannes Tschofenig (Hannes.Tschofenig@gmx.net) is the document shepherd. | ||
| Send notices to | Hannes.Tschofenig@gmx.net | ||
Internet Engineering Task Force (IETF) D. M'Raihi
Request for Comments: 6238 Verisign, Inc.
Category: Informational S. Machani
ISSN: 2070-1721 Diversinet Corp.
M. Pei
Symantec
J. Rydell
Portwise, Inc.
May 2011
TOTP: Time-Based One-Time Password Algorithm
Abstract
This document describes an extension of the One-Time Password (OTP)
algorithm, namely the HMAC-based One-Time Password (HOTP) algorithm,
as defined in RFC 4226, to support the time-based moving factor. The
HOTP algorithm specifies an event-based OTP algorithm, where the
moving factor is an event counter. The present work bases the moving
factor on a time value. A time-based variant of the OTP algorithm
provides short-lived OTP values, which are desirable for enhanced
security.
The proposed algorithm can be used across a wide range of network
applications, from remote Virtual Private Network (VPN) access and
Wi-Fi network logon to transaction-oriented Web applications. The
authors believe that a common and shared algorithm will facilitate
adoption of two-factor authentication on the Internet by enabling
interoperability across commercial and open-source implementations.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are 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/rfc6238.
M'Raihi, et al. Informational [Page 1]
RFC 6238 HOTPTimeBased May 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
(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 ....................................................2
1.1. Scope ......................................................2
1.2. Background .................................................3
2. Notation and Terminology ........................................3
3. Algorithm Requirements ..........................................3
4. TOTP Algorithm ..................................................4
4.1. Notations ..................................................4
4.2. Description ................................................4
5. Security Considerations .........................................5
5.1. General ....................................................5
5.2. Validation and Time-Step Size ..............................6
6. Resynchronization ...............................................7
7. Acknowledgements ................................................7
8. References ......................................................8
8.1. Normative References .......................................8
8.2. Informative References .....................................8
Appendix A. TOTP Algorithm: Reference Implementation ...............9
Appendix B. Test Vectors ..........................................14
1. Introduction
1.1. Scope
This document describes an extension of the One-Time Password (OTP)
algorithm, namely the HMAC-based One-Time Password (HOTP) algorithm,
as defined in [RFC4226], to support the time-based moving factor.
M'Raihi, et al. Informational [Page 2]
RFC 6238 HOTPTimeBased May 2011
1.2. Background
As defined in [RFC4226], the HOTP algorithm is based on the
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