NAME
RMD160Init,
RMD160Update, RMD160Pad,
RMD160Final,
RMD160Transform, RMD160End,
RMD160File, RMD160FileChunk,
RMD160Data —
calculate the RIPEMD-160 message
digest
SYNOPSIS
#include
<sys/types.h>
#include <rmd160.h>
void
RMD160Init(RMD160_CTX
*context);
void
RMD160Update(RMD160_CTX
*context, const u_int8_t
*data, size_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
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 MD5 functions and at least as secure as the SHA1 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
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('\n');
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%s\n", RMD160Data(buf, strlen(buf), output));
SEE ALSO
cksum(1), MD5Init(3), SHA1Init(3), SHA256Init(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.