NAME    [Toc]    [Back]

     md5 - calculate a message-digest fingerprint (checksum)  for
a file

SYNOPSIS    [Toc]    [Back]

     md5  [-p  |  -t | -x | -c [checklist ...] | -s string | file
...]

DESCRIPTION    [Toc]    [Back]

     md5 takes as input a message of arbitrary  length  and  produces as output a
     128-bit  "fingerprint" or "message digest" of the input.  It
was conjectured
 that it would be computationally infeasible to produce
two messages
     having  the same message digest (a collision), or to produce
any message
     having a given prespecified target message digest.  However,
collisions
     have  now been produced for MD5, so the use of other message
digest functions,
 such as sha1(1), is now preferred.

     The MD5 algorithm is intended for digital signature applications, where a
     large  file  must  be "compressed" in a secure manner before
being encrypted
     with a private (secret) key under a public-key  cryptosystem
such as RSA.

     The options are as follows:

     -c [checklist ...]
             Compares   all   checksums  contained  in  the  file
checklist with newly
             computed  checksums  for  the  corresponding  files.
Output consists
             of  the  digest  used,  the  file name, and an OK or
FAILED for the
             result of the comparison.  This will validate any of
the supported
  checksums  (see cksum(1)).  If no file is given,
stdin is used.

     -p      Echoes stdin to stdout and appends the  MD5  sum  to
stdout.

     -s string
             Prints a checksum of the given string.

     -t      Runs a built-in time trial.

     -x      Runs a built-in test script.

     The  MD5  sum  of  each  file  listed on the command line is
printed after the
     options are processed.

SEE ALSO    [Toc]    [Back]

     cksum(1), rmd160(1), sha1(1)

     R. Rivest, The MD5 Message-Digest Algorithm, RFC 1321.

BUGS    [Toc]    [Back]

     Since collisions have been found for MD5, the use of sha1(1)
is recommended
 instead.

OpenBSD      3.6                          April      30,     2004