One Time Password Authentication (otp)

NOTE: This charter is a snapshot of that in effect at the time of the 38th IETF Meeting in Memphis, Tennessee. It may now be out-of-date.


Neil Haller <>
Ran Atkinson <>

Security Area Director(s): 

Jeffrey Schiller <>

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Description of Working Group: 

One form of attack on computing systems connected to the Internet is eavesdropping on network connections to obtain login id's and passwords of legitimate users [RFC 1704]. Bellcore's S/KEY(TM) one-time password system was designed to counter this type of attack, called a replay attack [RFC 1760]. Several one-time password implementations compatible with Bellcore's S/KEY (TM) system exist. These implementations are increasingly widely deployed in the Internet to protect against passive attacks. 

The object of this working group is to write a standards track RFC for one-time password technology, using the technology in the Bellcore S/KEY system and related interoperable packages (e.g., logdaemon, NRL OPIE) as the basis for the group's effort. The standards-track RFC will enhance multi-vendor interoperability in one-time password authentication technologies and thereby help reduce security risks in the Internet. 

General authentication servers are outside the scope of this working group. The ``S/Key-0'' system being considered for use in Kerberos is outside the scope of this working group. 

The standards-track specification will describe how this one-time password technology can be used with at least the MD4, MD5, and SHA algorithms. The standard one-time password dictionary from RFC 1760 will be reused in order to maintain backwards compatibility with the various deployed systems, however, support for hexadecimal format passwords will also be mandatory to implement. The standard might specify passphrase quality checks for the secret passphrase. The standard will be specified so as to eliminate any possible conflict with the Bellcore trademark on the term ``S/Key.'' 

An Informational RFC might also be issued that describes conventions for the UNIX commands relating to one-time passwords, including command(s) to securely update a remote one-time password.

Goals and Milestones:


Reach agreement on required and optional attributes.


Produce Internet-Draft specifying the IETF one-time password authentication technology.


Final review (Working Group Last Call) of the Internet-Draft.


Submit One-Time Password document to IESG for consideration as a Proposed Standard.

Aug 96 

Submit Internet-Draft on optional extensions to OTP.

Dec 96 

Submit Internet-Draft on OTP optional Extensions to IESG for consideration of publication as an RFC.


· OTP Extended Responses 

· OTP Verification Examples 

· A One-Time Password System

Request For Comments:






A One-Time Password System

Current Meeting Report

The Working Group did not meet. 


None Received 

Attendees List