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OpenDarwin 7.2.1 - man page for md5 (opendarwin section 1)

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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
     Md5 takes as input a message of arbitrary length and produces as output a 128-bit
     ``fingerprint'' or ``message digest'' of the input.  It is conjectured that it is computa-
     tionally infeasible to produce two messages having the same message digest, or to produce
     any message having a given prespecified target 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 cryp-
     tosystem 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 MD5 sum 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 appends the MD5 sum to stdout.

     -q      Quiet mode - only the MD5 sum 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.

SEE ALSO
     cksum(1)

     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					February 14, 1994				      BSD
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