MD5(1) BSD General Commands Manual MD5(1)NAMEmd5 — calculate a message-digest fingerprint (checksum) for a file
SYNOPSISmd5 [-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 conjec‐
tured that it is computationally infeasible to produce two messages hav‐
ing 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
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 ALSOcksum(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
