NAME

       RMD160Init,    RMD160Update,    RMD160Pad,    RMD160Final,    RMD160Transform,   RMD160End,   RMD160File,
       RMD160FileChunk, RMD160Data — calculate the ``RIPEMD-160'' message digest

LIBRARY

       Message Digest (MD4, MD5, etc.) Support Library (libmd, -lmd)

SYNOPSIS

       #include <sys/types.h>
       #include <rmd160.h>

       void
       RMD160Init(RMD160_CTX *context);

       void
       RMD160Update(RMD160_CTX *context, const uint8_t *data, uint32_t nbytes);

       void
       RMD160Pad(RMD160_CTX *context);

       void
       RMD160Final(uint8_t digest[RMD160_DIGEST_LENGTH], RMD160_CTX *context);

       void
       RMD160Transform(uint32_t state[5], const uint8_t block[RMD160_BLOCK_LENGTH]);

       char *
       RMD160End(RMD160_CTX *context, char *buf);

       char *
       RMD160File(const char *filename, char *buf);

       char *
       RMD160FileChunk(const char *filename, char *buf, off_t offset, off_t length);

       char *
       RMD160Data(const uint8_t *data, size_t len, char *buf);

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.

       The RMD160 functions are considered to be more secure than the md4(3), md5(3) and sha1(3) functions.  All
       share a similar interface.

       The  RMD160Init()  function  initializes  a  RMD160_CTX  context  for  use   with   RMD160Update(),   and
       RMD160Final().   The  RMD160Update()  function  adds data of length nbytes to the RMD160_CTX specified by
       context.  RMD160Final() is called when all data has been added via RMD160Update() and  stores  a  message
       digest in the digest parameter.

       The  RMD160Pad() function can be used to apply padding to the message digest as in RMD160Final(), but the
       current context can still be used with RMD160Update().

       The RMD160Transform() function is used by RMD160Update() to hash 512-bit blocks and forms the core of the
       algorithm.  Most  programs  should  use  the  interface  provided  by  RMD160Init(),  RMD160Update()  and
       RMD160Final() instead of calling RMD160Transform() directly.

       The  RMD160End()  function  is  a  front  end  for  RMD160Final() which converts the digest into an ASCII
       representation of the 160 bit digest in hexadecimal.

       The RMD160File() function calculates the digest for a file and returns the result  via  RMD160End().   If
       RMD160File() is unable to open the file a NULL pointer is returned.

       RMD160FileChunk()  behaves  like RMD160File() but calculates the digest only for that portion of the file
       starting at offset and continuing for length bytes or until end  of  file  is  reached,  whichever  comes
       first.   A  zero  length can be specified to read until end of file.  A negative length or offset will be
       ignored.

       The RMD160Data() function calculates the digest of  an  arbitrary  string  and  returns  the  result  via
       RMD160End().

       For  each of the RMD160End(), RMD160File(), and RMD160Data() functions the 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 malloc(3) and should be freed using free(3) when it is no longer needed.

EXAMPLES

       The   follow   code   fragment   will   calculate   the   digest   for   the   string   "abc"   which  is
       ``0x8eb208f7e05d987a9b044a8e98c6b087f15a0bfc''.

             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('\n');

       Alternately, the helper functions could be used in the following way:

             RMD160_CTX rmd;
             uint8_t output[RMD160_DIGEST_STRING_LENGTH];
             char *buf = "abc";

             printf("0x%s\n", RMD160Data(buf, strlen(buf), output));

SEE ALSO

       cksum(1), md4(3), md5(3), sha1(3), sha2(3)

       H. Dobbertin, A. Bosselaers, B. Preneel, RIPEMD-160, a strengthened version of RIPEMD.

       Information technology - Security techniques - Hash-functions - Part 3: Dedicated hash-functions, ISO/IEC
       10118-3.

       H. Dobbertin, A. Bosselaers, B.  Preneel,  “The  RIPEMD-160  cryptographic  hash  function”,  Dr.  Dobb's
       Journal, Vol. 22, No. 1, pp. 24-28, January 1997.

HISTORY

       The RMD-160 functions appeared in OpenBSD 2.1.

AUTHORS

       This implementation of RMD-160 was written by Markus Friedl.

       The RMD160End(), RMD160File(), RMD160FileChunk(), and RMD160Data() helper functions are derived from code
       written by Poul-Henning Kamp.

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.

Debian                                            July 13, 2010                                        RMD160(3)