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MD5(1)                                   BSD General Commands Manual                                  MD5(1)

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

SYNOPSIS
     md5 [-pqrtx] [-s string] [file ...]

DESCRIPTION
     The md5 utility takes as input a message of arbitrary length and produces as output a ``fingerprint''
     or ``message digest'' of the input.  It is conjectured that it is computationally infeasible to produce
     two messages having the same message digest, or to produce any message having a given prespecified tar-get target
     get message digest.  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.

     MD5 has not yet (2001-09-03) been broken, but sufficient attacks have been made that its security is in
     some doubt.  The attacks on MD5 are in the nature of finding ``collisions'' -- that is, multiple inputs
     which hash to the same value; it is still unlikely for an attacker to be able to determine the exact
     original input given a hash value.

     The following options may be used in any combination and must precede any files named on the command
     line.  The hexadecimal checksum of each file listed on the command line is printed after the options
     are processed.

     -s string
             Print a checksum of the given string.

     -p      Echo stdin to stdout and append the checksum to stdout.

     -q      Quiet mode - only the checksum is printed out.  Overrides the -r option.

     -r      Reverses the format of the output.  This helps with visual diffs.  Does nothing when combined
             with the -ptx options.

     -t      Run a built-in time trial.

     -x      Run a built-in test script.

EXIT STATUS
     The md5 utility exits 0 on success, and 1 if at least one of the input files could not be read.

SEE ALSO
     cksum(1), md5(3), ripemd(3), sha(3)

     R. Rivest, The MD5 Message-Digest Algorithm, RFC1321.

ACKNOWLEDGMENTS
     This program is placed in the public domain for free general use by RSA Data Security.

BSD                                             June 6, 2004                                             BSD