SKEY(1)                    OpenBSD Reference Manual                    SKEY(1)

NAME
     skey, otp-md4, otp-md5, otp-rmd160, otp-sha1 - respond to an OTP chal-
     lenge

SYNOPSIS
     skey [-x] [-md4 | -md5 | -rmd160 | -sha1] [-n count] [-p passphrase]
          <sequence#>[/] key

DESCRIPTION
     S/Key is a procedure for using one-time passwords to authenticate access
     to computer systems.  It uses 64 bits of information transformed by the
     MD4, MD5, RIPEMD-160, or SHA1 algorithms.  The user supplies the 64 bits
     in the form of 6 English words that are generated by a secure computer.
     This implementation of S/Key is RFC 2289 compliant.

     Before using skey the system needs to be initialized using skeyinit(1);
     this will establish a secret passphrase.  After that, one-time passwords
     can be generated using skey, which will prompt for the secret passphrase.
     After a one-time password has been used to log in, it can no longer be
     used.

     When skey is invoked as otp-method, skey will use method as the hash
     function where method is currently one of md4, md5, rmd160, or sha1.

     If you misspell your secret passphrase while running skey, you will get a
     list of one-time passwords that will not work, and no indication of the
     problem.

     Password sequence numbers count backwards.  You can enter the passwords
     using small letters, even though skey prints them capitalized.

     The options are as follows:

     -md4 | -md5 | -rmd160 | -sha1
             Selects the hash algorithm: MD4, MD5, RMD-160 (160-bit Ripe Mes-
             sage Digest), or SHA1 (NIST Secure Hash Algorithm Revision 1).

     -n count
             Prints out count one-time passwords.  The default is to print
             one.

     -p passphrase
             Uses passphrase as the secret passphrase.  Use of this option is
             discouraged as your secret passphrase could be visible in a pro-
             cess listing.

     -x      Causes output to be in hexadecimal instead of ASCII.

EXAMPLES
           $ skey 99 th91334
           Reminder - Do not use this program while logged in via telnet.
           Enter secret passphrase: <your secret passphrase is entered here>
           OMEN US HORN OMIT BACK AHOY
           $

SEE ALSO
     login(1), skeyaudit(1), skeyinfo(1), skeyinit(1), skey(5), skeyprune(8)

     A One-Time Password System, RFC 2289, 1998.

TRADEMARKS AND PATENTS
     S/Key is a Trademark of Bellcore.

AUTHORS
     Phil Karn, Neil M. Haller, John S. Walden, Scott Chasin

OpenBSD 4.7                      May 31, 2007                                2
