NAME
MD2Init,
MD2Update,
MD2Final,
MD2End,
MD2File,
MD2Data —
calculate the RSA Data Security, Inc., “MD2”
message digest
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <mdX.h>
void
MD2Init(
MD2_CTX
*context);
void
MD2Update(
MD2_CTX
*context,
const unsigned
char *data,
unsigned int
len);
void
MD2Final(
unsigned
char digest[16],
MD2_CTX
*context);
char *
MD2End(
MD2_CTX
*context,
char *buf);
char *
MD2File(
const
char *filename,
char
*buf);
char *
MD2Data(
const
unsigned char *data,
unsigned int len,
char *buf);
DESCRIPTION
The MD2 functions calculate a 128-bit cryptographic checksum (digest) for any
number of input bytes. A cryptographic checksum is a one-way hash-function,
that is, you cannot find (except by exhaustive search) the input corresponding
to a particular output. This net result is a ``fingerprint'' of the
input-data, which doesn't disclose the actual input.
The MD2 routines should not be used for any security-related purpose.
The
MD2Init(),
MD2Update(), and
MD2Final() functions are the core functions. Allocate an
MD2_CTX, initialize it with
MD2Init(), run over the data
with
MD2Update(), and finally extract the result using
MD2Final().
MD2End() is a wrapper for
MD2Final() which
converts the return value to a 33-character (including the terminating '\0')
ASCII string which represents the 128 bits in hexadecimal.
MD2File() calculates the digest of a file, and uses
MD2End() to return the result. If the file cannot be opened,
a null pointer is returned.
MD2Data() calculates the digest
of a chunk of data in memory, and uses
MD2End() to return
the result.
When using
MD2End(),
MD2File(), or
MD2Data(), the
buf argument can be a
null pointer, in which case the returned string is allocated with
malloc(3) and subsequently must
be explicitly deallocated using
free(3) after use. If the
buf argument is non-null it must point to at least 33
characters of buffer space.
SEE ALSO
md2(3),
B. Kaliski, The MD2
Message-Digest Algorithm, RFC 1319.
RSA Laboratories,
Frequently Asked Questions About today's
Cryptography.
HISTORY
These functions appeared in
NetBSD 1.3.
AUTHORS
The original MD2 routines were developed by RSA Data Security, Inc., and
published in the above references. This code is a public domain implementation
by Andrew Brown.
BUGS
No method is known to exist which finds two files having the same hash value,
nor to find a file with a specific hash value. There is on the other hand no
guarantee that such a method doesn't exist.