MD5(3bsd) LOCAL MD5(3bsd)
NAME
MD5Init, MD5Update, MD5Pad, MD5Final, MD5Transform, MD5End, MD5File, MD5FileChunk, MD5Data -- calculate the RSA Data Security, Inc., ``MD5''
message digest
LIBRARY
Utility functions from BSD systems (libbsd, -lbsd)
SYNOPSIS
#include <sys/types.h>
#include <bsd/md5.h>
void
MD5Init(MD5_CTX *context);
void
MD5Update(MD5_CTX *context, const u_int8_t *data, size_t len);
void
MD5Pad(MD5_CTX *context);
void
MD5Final(u_int8_t digest[MD5_DIGEST_LENGTH], MD5_CTX *context);
void
MD5Transform(u_int32_t state[4], u_int8_t block[MD5_BLOCK_LENGTH]);
char *
MD5End(MD5_CTX *context, char *buf);
char *
MD5File(const char *filename, char *buf);
char *
MD5FileChunk(const char *filename, char *buf, off_t offset, off_t length);
char *
MD5Data(const u_int8_t *data, size_t len, char *buf);
DESCRIPTION
The MD5 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.
MD4 has been broken; it should only be used where necessary for backward compatibility. MD5 has not yet (1999-02-11) been broken, but recent
attacks have cast some doubt on its security properties. The attacks on both MD4 and MD5 are both in the nature of finding ``collisions'' -
that is, multiple inputs which hash to the same value; it is still unlikely for an attacker to be able to determine the exact original input
given a hash value.
The MD5Init(), MD5Update(), and MD5Final() functions are the core functions. Allocate an MD5_CTX, initialize it with MD5Init(), run over the
data with MD5Update(), and finally extract the result using MD5Final().
The MD5Pad() function can be used to apply padding to the message digest as in MD5Final(), but the current context can still be used with
MD5Update().
The MD5Transform() function is used by MD5Update() to hash 512-bit blocks and forms the core of the algorithm. Most programs should use the
interface provided by MD5Init(), MD5Update() and MD5Final() instead of calling MD5Transform() directly.
MD5End() is a wrapper for MD5Final() which converts the return value to an MD5_DIGEST_STRING_LENGTH-character (including the terminating
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