One Time Password Authentication

Document Charter One Time Password Authentication WG (otp)
Title One Time Password Authentication
Last updated 2002-10-29
State Approved
WG State Concluded
IESG Responsible AD (None)
Charter Edit AD (None)
Send notices to (None)


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

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.