MD5(1)                       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 “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's designer Ron Rivest has stated "md5 and sha1 are both clearly broken
     (in terms of collision-resistance)".  So MD5 should be avoided when
     creating new protocols, or implementing protocols with better options.
     SHA256 and SHA512 are better options as they have been more resilient to
     attacks (as of 2009).

     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

     -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.

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

     cksum(1), CC_SHA256_Init(3), md5(3), ripemd(3), sha(3)

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

     Vlastimil Klima, Finding MD5 Collisions - a Toy For a Notebook, Cryptology
     ePrint Archive: Report 2005/075.

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

macOS 12.1                        June 6, 2004                        macOS 12.1