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.
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
macOS 12.1 June 6, 2004 macOS 12.1