MD5(1) BSD Reference Manual MD5(1)
md5 - calculate a message-digest fingerprint (checksum) for a file
md5 [-b] [-p | -s string | file ...] md5 -G [file ...] md5 -t | -x | -c [checklist ...] md5sum [-b | -t] [file ...]
md5 takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. It was conjec- tured that it would be computationally infeasible to produce two messages having the same message digest (a collision), or to produce any message having a given prespecified target message digest. However, collisions have now been produced for MD5, so the use of other message digest func- tions is now preferred. 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. The options are as follows: -b Print the checksum as binary to stdout. Ignored in GNU mode. -c [checklist ...] Compares all checksums contained in the file checklist with newly computed checksums for the corresponding files. Output consists of the digest used, the file name, and an OK or FAILED for the result of the comparison. This will validate any of the supported checksums (see cksum(1)). If no file is given, stdin is used. -G Enable GNU md5sum compatible output mode. Can also be enabled by calling this programme as md5sum. -p Echoes stdin to stdout and appends the MD5 sum to stdout. -s string Prints a checksum of the given string. -t Runs a built-in time trial. Ignored in GNU mode. -x Runs a built-in test script. The MD5 sum of each file listed on the command line is printed after the options are processed.
cksum(1), rmd160(1), sha1(1) R. Rivest, The MD5 Message-Digest Algorithm, RFC 1321.
Since collisions have been found for MD5, the use of rmd160(1) or sha1(1) is recommended instead. MirOS BSD #10-current November 17, 2009 1
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