NAME    [Toc]    [Back]

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

SYNOPSIS    [Toc]    [Back]

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

     void
     RMD160Init(RMD160_CTX *context);

     void
     RMD160Update(RMD160_CTX *context, const u_int8_t *data,
             u_int32_t nbytes);

     void
     RMD160Pad(RMD160_CTX *context);

     void
     RMD160Final(u_int8_t           digest[RMD160_DIGEST_LENGTH],
RMD160_CTX *context);

     void
     RMD160Transform(u_int32_t state[5],
             const u_int8_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 u_int8_t *data, size_t len, char *buf);

DESCRIPTION    [Toc]    [Back]

     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) and
     md5(3) functions and at least as secure as the sha1(3) function.  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    [Toc]    [Back]

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

           RMD160_CTX rmd;
           u_int8_t results[RMD160_DIGEST_LENGTH];
           char *buf;
           int n;

           buf = "abc";
           n = strlen(buf);
           RMD160Init(&rmd);
           RMD160Update(&rmd, (u_int8_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('0);

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

           RMD160_CTX rmd;
           u_int8_t output[RMD160_DIGEST_STRING_LENGTH];
           char *buf = "abc";

           printf("0x%s0, RMD160Data(buf, strlen(buf), output));

SEE ALSO    [Toc]    [Back]

     cksum(1), rmd160(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
     Information0 0Information1 1Information2, 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    [Toc]    [Back]

     The RMD-160 functions appeared in OpenBSD 2.1.

AUTHORS    [Toc]    [Back]

     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    [Toc]    [Back]

     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.

OpenBSD      3.6                          April      29,     2004