.\" $OpenBSD: rmd160.3,v 1.30 2010/07/13 07:01:23 jmc Exp $ .\" .\" Copyright (c) 1997, 2004 Todd C. Miller .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .\" See http://www.esat.kuleuven.ac.be/~bosselae/ripemd160.html .\" for detailed information about RIPEMD-160. .\" .Dd $Mdocdate: July 13 2010 $ .Dt RMD160 3 .Os .Sh NAME .Nm RMD160Init , .Nm RMD160Update , .Nm RMD160Pad , .Nm RMD160Final , .Nm RMD160Transform , .Nm RMD160End , .Nm RMD160File , .Nm RMD160FileChunk , .Nm RMD160Data .Nd calculate the ``RIPEMD-160'' message digest .Sh LIBRARY .Lb libmd .Sh SYNOPSIS .Fd #include .Fd #include .Ft void .Fn RMD160Init "RMD160_CTX *context" .Ft void .Fn RMD160Update "RMD160_CTX *context" "const uint8_t *data" "uint32_t nbytes" .Ft void .Fn RMD160Pad "RMD160_CTX *context" .Ft void .Fn RMD160Final "uint8_t digest[RMD160_DIGEST_LENGTH]" "RMD160_CTX *context" .Ft void .Fn RMD160Transform "uint32_t state[5]" "const uint8_t block[RMD160_BLOCK_LENGTH]" .Ft "char *" .Fn RMD160End "RMD160_CTX *context" "char *buf" .Ft "char *" .Fn RMD160File "const char *filename" "char *buf" .Ft "char *" .Fn RMD160FileChunk "const char *filename" "char *buf" "off_t offset" "off_t length" .Ft "char *" .Fn RMD160Data "const uint8_t *data" "size_t len" "char *buf" .Sh DESCRIPTION The RMD160 functions implement the 160-bit RIPE message digest hash algorithm (RMD-160). RMD-160 is used to generate a condensed representation of a message called a message digest. The algorithm takes a message less than 2^64 bits as input and produces a 160-bit digest suitable for use as a digital signature. .Pp The RMD160 functions are considered to be more secure than the .Xr md4 3 and .Xr md5 3 functions and at least as secure as the .Xr sha1 3 function. All share a similar interface. .Pp The .Fn RMD160Init function initializes a RMD160_CTX .Ar context for use with .Fn RMD160Update , and .Fn RMD160Final . The .Fn RMD160Update function adds .Ar data of length .Ar nbytes to the RMD160_CTX specified by .Ar context . .Fn RMD160Final is called when all data has been added via .Fn RMD160Update and stores a message digest in the .Ar digest parameter. .Pp The .Fn RMD160Pad function can be used to apply padding to the message digest as in .Fn RMD160Final , but the current context can still be used with .Fn RMD160Update . .Pp The .Fn RMD160Transform function is used by .Fn RMD160Update to hash 512-bit blocks and forms the core of the algorithm. Most programs should use the interface provided by .Fn RMD160Init , .Fn RMD160Update and .Fn RMD160Final instead of calling .Fn RMD160Transform directly. .Pp The .Fn RMD160End function is a front end for .Fn RMD160Final which converts the digest into an .Tn ASCII representation of the 160 bit digest in hexadecimal. .Pp The .Fn RMD160File function calculates the digest for a file and returns the result via .Fn RMD160End . If .Fn RMD160File is unable to open the file a NULL pointer is returned. .Pp .Fn RMD160FileChunk behaves like .Fn RMD160File but calculates the digest only for that portion of the file starting at .Fa offset and continuing for .Fa length bytes or until end of file is reached, whichever comes first. A zero .Fa length can be specified to read until end of file. A negative .Fa length or .Fa offset will be ignored. .Pp The .Fn RMD160Data function calculates the digest of an arbitrary string and returns the result via .Fn RMD160End . .Pp For each of the .Fn RMD160End , .Fn RMD160File , and .Fn RMD160Data functions the .Ar buf parameter should either be a string of at least 41 characters in size or a NULL pointer. In the latter case, space will be dynamically allocated via .Xr malloc 3 and should be freed using .Xr free 3 when it is no longer needed. .Sh EXAMPLES The follow code fragment will calculate the digest for the string "abc" which is ``0x8eb208f7e05d987a9b044a8e98c6b087f15a0bfc''. .Bd -literal -offset indent RMD160_CTX rmd; uint8_t results[RMD160_DIGEST_LENGTH]; char *buf; int n; buf = "abc"; n = strlen(buf); RMD160Init(&rmd); RMD160Update(&rmd, (uint8_t *)buf, n); RMD160Final(results, &rmd); /* Print the digest as one long hex value */ printf("0x"); for (n = 0; n < RMD160_DIGEST_LENGTH; n++) printf("%02x", results[n]); putchar('\en'); .Ed .Pp Alternately, the helper functions could be used in the following way: .Bd -literal -offset indent RMD160_CTX rmd; uint8_t output[RMD160_DIGEST_STRING_LENGTH]; char *buf = "abc"; printf("0x%s\en", RMD160Data(buf, strlen(buf), output)); .Ed .Sh SEE ALSO .Xr cksum 1 , .Xr md4 3 , .Xr md5 3 , .Xr sha1 3 , .Xr sha2 3 .Rs .%A H. Dobbertin, A. Bosselaers, B. Preneel .%T RIPEMD-160, a strengthened version of RIPEMD .Re .Rs .%T Information technology - Security techniques - Hash-functions - Part 3: Dedicated hash-functions .%O ISO/IEC 10118-3 .Re .Rs .%A H. Dobbertin, A. Bosselaers, B. Preneel .%T The RIPEMD-160 cryptographic hash function .%J Dr. Dobb's Journal .%V Vol. 22, No. 1 .%D January 1997 .%P pp. 24-28 .Re .Sh HISTORY The RMD-160 functions appeared in .Ox 2.1 . .Sh AUTHORS This implementation of RMD-160 was written by Markus Friedl. .Pp The .Fn RMD160End , .Fn RMD160File , .Fn RMD160FileChunk , and .Fn RMD160Data helper functions are derived from code written by Poul-Henning Kamp. .Sh CAVEATS If a message digest is to be copied to a multi-byte type (ie: an array of five 32-bit integers) it will be necessary to perform byte swapping on little endian machines such as the i386, alpha, and vax.