NAME
RMD160Init,
RMD160Update,
RMD160Final,
RMD160Transform,
RMD160End,
RMD160File,
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_char
*data,
u_int nbytes);
void
RMD160Final(
u_char
digest[20],
RMD160_CTX
*context);
void
RMD160Transform(
uint32_t
state[5],
const uint32_t
block[16]);
char *
RMD160End(
RMD160_CTX
*context,
char *buf);
char *
RMD160File(
char
*filename,
char
*buf);
char *
RMD160Data(
u_char
*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) 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. When a null
pointer is passed to
RMD160Final() as first argument only
the final padding will be applied and 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.
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_char results[20];
char *buf;
int n;
buf = "abc";
n = strlen(buf);
RMD160Init(&rmd);
RMD160Update(&rmd, (u_char *)buf, n);
RMD160Final(results, &rmd);
/* Print the digest as one long hex value */
printf("0x");
for (n = 0; n < 20; n++)
printf("%02x", results[n]);
putchar('\n');
Alternately, the helper functions could be used in the following way:
RMD160_CTX rmd;
u_char output[41];
char *buf = "abc";
printf("0x%s\n", RMD160Data(buf, strlen(buf), output));
SEE ALSO
rmd160(1),
md4(3),
md5(3),
sha1(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 Antoon Bosselaers.
The
RMD160End(),
RMD160File(), and
RMD160Data() helper functions are derived from code written
by Poul-Henning Kamp.
BUGS
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.