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MD5(1)                  FreeBSD General Commands Manual                 MD5(1)

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

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

     The md5 utility 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 computationally 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 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 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

     -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.


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

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

FreeBSD 4.10                   February 14, 1994                  FreeBSD 4.10


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