NAME¶
mhash - Hash Library
VERSION¶
mhash 0.9.2
SYNOPSIS¶
#include "mhash.h"
Informative Functions
size_t mhash_count(void);
size_t mhash_get_block_size(hashid type);
char *mhash_get_hash_name(hashid type);
size_t mhash_get_hash_pblock(hashid type);
hashid mhash_get_mhash_algo( MHASH);
Key Generation Functions
int mhash_keygen_ext(keygenid algorithm, KEYGEN algorithm_data,
void* keyword, int keysize,
unsigned char* password, int passwordlen);
Initializing Functions
MHASH mhash_init(hashid type);
MHASH mhash_hmac_init(const hashid type, void *key, int keysize, int block);
MHASH mhash_cp( MHASH);
Update Functions
int mhash(MHASH thread, const void *plaintext, size_t size);
Save/Restore Functions
int mhash_save_state_mem(MHASH thread, void *mem, int* mem_size );
MHASH mhash_restore_state_mem(void* mem);
Finalizing Functions
void mhash_deinit(MHASH thread, void *result);
void *mhash_end(MHASH thread);
void *mhash_end_m(MHASH thread, void* (*hash_malloc)(size_t));
void *mhash_hmac_end(MHASH thread);
void *mhash_hmac_end_m(MHASH thread, void* (*hash_malloc)(size_t));
int mhash_hmac_deinit(MHASH thread, void *result);
Available Hashes
CRC32: The crc32 algorithm is used to compute checksums. The two variants
used in mhash are:
MHASH_CRC32 (like the one used in ethernet) and
MHASH_CRC32B (like the one used in ZIP programs).
ADLER32: The adler32 algorithm is used to compute checksums. It is faster
than CRC32 and it is considered to be as reliable as CRC32. This algorithm is
defined as
MHASH_ADLER32.
MD5: The MD5 algorithm by Ron Rivest and RSA. In mhash this algorithm is
defined as
MHASH_MD5.
MD4: The MD4 algorithm by Ron Rivest and RSA. This algorithm is
considered broken, so don't use it. In mhash this algorithm is defined as
MHASH_MD4.
SHA1/
SHA256: The SHA algorithm by US. NIST/NSA. This algorithm is
specified for use in the NIST's Digital Signature Standard. In mhash these
algorithm are defined as
MHASH_SHA1 and
MHASH_SHA256.
HAVAL: HAVAL is a one-way hashing algorithm with variable length of
output. HAVAL is a modification of MD5. Defined in mhash as:
MHASH_HAVAL256, MHASH_HAVAL192, MHASH_HAVAL160, MHASH_HAVAL128.
RIPEMD160: RIPEMD-160 is a 160-bit cryptographic hash function, designed
by Hans Dobbertin, Antoon Bosselaers, and Bart Preneel. It is intended to be
used as a secure replacement for the 128-bit hash functions MD4, MD5, and
RIPEMD. MD4 and MD5 were developed by Ron Rivest for RSA Data Security, while
RIPEMD was developed in the framework of the EU project RIPE (RACE Integrity
Primitives Evaluation, 1988-1992). In mhash this algorithm is defined as
MHASH_RIPEMD160.
TIGER: Tiger is a fast hash function, by Eli Biham and Ross Anderson.
Tiger was designed to be very fast on modern computers, and in particular on
the state-of-the-art 64-bit computers, while it is still not slower than other
suggested hash functions on 32-bit machines. In mhash this algorithm is
defined as:
MHASH_TIGER, MHASH_TIGER160, MHASH_TIGER128.
GOST: GOST algorithm is a russian standard and it uses the GOST
encryption algorithm to produce a 256 bit hash value. This algorithm is
specified for use in the Russian Digital Signature Standard. In mhash this
algorithm is defined as
MHASH_GOST.
Available Key Generation algorithms
KEYGEN_MCRYPT: The key generator used in mcrypt.
KEYGEN_ASIS: Just returns the password as binary key.
KEYGEN_HEX: Just converts a hex key into a binary one.
KEYGEN_PKDES: The transformation used in Phil Karn's DES encryption
program.
KEYGEN_S2K_SIMPLE: The OpenPGP (rfc2440) Simple S2K.
KEYGEN_S2K_SALTED: The OpenPGP Salted S2K.
KEYGEN_S2K_ISALTED: The OpenPGP Iterated Salted S2K.
DESCRIPTION¶
The
mhash library provides an easy to use C interface for several
hash algorithms (also known as "one-way" algorithms).
These can be used to create checksums, message digests and more. Currently,
MD5, SHA1, GOST, TIGER, RIPE-MD160, HAVAL and several other algorithms are
supported.
mhash support
HMAC generation (a mechanism for
message authentication using cryptographic hash functions, and is described in
rfc2104). HMAC can be used to create message digests using a secret key, so
that these message digests cannot be regenerated (or replaced) by someone
else. A key generation mechanism was added to
mhash since
key
generation algorithms usually involve hash algorithms.
API FUNCTIONS¶
We will describe the API of
mhash in detail now. The order follows the
one in the SYNOPSIS directly.
- size_t mhash_count(void);
- This returns the "hashid" of the last available hash. Hashes are
numbered from 0 to "mhash_count()".
- size_t mhash_get_block_size(hashid type);
- If type exists, this returns the used blocksize of the hash
type in bytes. Otherwise, it returns 0.
- char *mhash_get_hash_name(hashid type);
- If type exists, this returns the name of the hash type.
Otherwise, a "NULL" pointer is returned. The string is allocated
with malloc(3) separately, so do not forget to free(3)
it.
- const char *mhash_get_hash_name_static(hashid type);
- If type exists, this returns the name of the hash type.
Otherwise, a "NULL" pointer is returned.
- size_t mhash_get_hash_pblock(hashid type);
- It returns the block size that the algorithm operates. This is used in
mhash_hmac_init. If the return value is 0 you shouldn't use that algorithm
in HMAC.
- hashid mhash_get_mhash_algo(MHASH src);
- Returns the algorithm used in the state of src.
- MHASH mhash_init(hashid type);
- This setups a context to begin hashing using the algorithm type. It
returns a descriptor to that context which will result in leaking memory,
if you do not call mhash_deinit(3) later. Returns
"MHASH_FAILED" on failure.
- MHASH mhash_hmac_init(const hashid type, void *key,
int keysize, int block);
- This setups a context to begin hashing using the algorithm type in HMAC
mode. key should be a pointer to the key and keysize its
len. The block is the block size (in bytes) that the algorithm
operates. It should be obtained by mhash_get_hash_pblock(). If its
0 it defaults to 64. After calling it you should use mhash() to
update the context. It returns a descriptor to that context which will
result in leaking memory, if you do not call mhash_hmac_deinit(3)
later. Returns "MHASH_FAILED" on failure.
- MHASH mhash_cp(MHASH src);
- This setups a new context using the state of src.
- int mhash(MHASH thread, const void *plaintext, size_t
size);
- This updates the context described by thread with plaintext.
size is the length of plaintext which may be binary
data.
- int mhash_save_state_mem( MHASH thread, void *mem,
int* mem_size);
- Saves the state of a hashing algorithm such that it can be restored at
some later point in time using mhash_restore_state_mem().
mem_size should contain the size of the given mem pointer.
If it is not enough to hold the buffer the required value will be copied
there.
- MHASH mhash_restore_state_mem(void* mem);
- Restores the state of a hashing algorithm that was saved using
mhash_save_state_mem(). Use like mhash_init().
- void *mhash_end(MHASH thread);
- This frees all resources associated with thread and returns the
result of the whole hashing operation (the `` digest'').
- void mhash_deinit(MHASH thread, void* digest);
- This frees all resources associated with thread and stores the
result of the whole hashing operation in memory pointed by digest.
digest may be null.
- void *mhash_hmac_end(MHASH thread);
- This frees all resources associated with thread and returns the result of
the whole hashing operation (the `` mac'').
- int mhash_hmac_deinit(MHASH thread, void* digest);
- This frees all resources associated with thread and stores the
result of the whole hashing operation in memory pointed by digest. Digest
may be null. Returns non-zero in case of an error.
- void *mhash_end_m(MHASH thread, void*
(*hash_malloc)(size_t));
- This frees all resources associated with thread and returns the
result of the whole hashing operation (the `` digest''). The result
will be allocated by using the hash_malloc() function
provided.
- void *mhash_hmac_end(MHASH thread, void*
(*hash_malloc)(size_t));
- This frees all resources associated with thread and returns the result of
the whole hashing operation (the `` mac''). The result will be
allocated by using the hash_malloc() function provided.
KEYGEN API FUNCTIONS¶
We will now describe the Key Generation API of
mhash in detail.
- int mhash_keygen_ext(keygenid algorithm, KEYGEN
algorithm_data, void* keyword, int keysize, unsigned
char* password, int passwordlen);
- This function, generates a key from a password. The password is read from
password and it's len should be in passwordlen. The key
generation algorithm is specified in algorithm, and that algorithm
may (internally) use the KEYGEN structure. The KEYGEN structure consists
of:
typedef struct keygen {
hashid hash_algorithm[2];
unsigned int count;
void* salt;
int salt_size;
} KEYGEN;
The algorithm(s) specified in algorithm_data.hash_algorithm, should
be hash algorithms and may be used by the key generation algorithm. Some
key generation algorithms may use more than one hash algorithms (view also
mhash_keygen_uses_hash_algorithm()). If it is desirable (and
supported by the algorithm, eg. KEYGEN_S2K_SALTED) a salt may be specified
in algorithm_data.salt of size algorithm_data.salt_size or
may be NULL.
The algorithm may use the algorithm_data.count internally (eg.
KEYGEN_S2K_ISALTED). The generated keyword is stored in keyword,
which should be (at least) keysize bytes long. The generated
keyword is a binary one. Returns a negative number on failure.
- int mhash_keygen_uses_salt( keygenid algorithm);
- This function returns 1 if the specified key generation algorithm needs a
salt to be specified.
- int mhash_keygen_uses_count( keygenid algorithm);
- This function returns 1 if the specified key generation algorithm needs
the algorithm_data.count field in mhash_keygen_ext(). The count
field tells the algorithm to hash repeatedly the password and to stop when
count bytes have been processed.
- int mhash_get_keygen_salt_size( keygenid algorithm);
- This function returns the size of the salt size, that the specific
algorithm will use. If it returns 0, then there is no limitation in
the size.
- int mhash_get_keygen_max_key_size( keygenid algorithm);
- This function returns the maximum size of the key, that the key generation
algorithm may produce. If it returns 0, then there is no limitation in the
size.
- int mhash_keygen_uses_hash_algorithm( keygenid
algorithm);
- This function returns the number of the hash algorithms the key generation
algorithm will use. If it is 0 then no hash algorithm is used by the key
generation algorithm. This is for the algorithm_data.hash_algorithm
field in mhash_keygen_ext(). If
- size_t mhash_keygen_count(void);
- This returns the "keygenid" of the last available key generation
algorithm. Algorithms are numbered from 0 to
"mhash_keygen_count()".
- char *mhash_get_keygen_name(keygenid type);
- If type exists, this returns the name of the keygen type.
Otherwise, a "NULL" pointer is returned. The string is allocated
with malloc(3) separately, so do not forget to free(3)
it.
- const char *mhash_get_keygen_name_static(keygenid
type);
- If type exists, this returns the name of the keygen type.
Otherwise, a "NULL" pointer is returned.
EXAMPLE¶
Hashing STDIN until EOF.
#include <mhash.h>
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
int i;
MHASH td;
unsigned char buffer;
unsigned char hash[16]; /* enough size for MD5 */
td = mhash_init(MHASH_MD5);
if (td == MHASH_FAILED) exit(1);
while (fread(&buffer, 1, 1, stdin) == 1) {
mhash(td, &buffer, 1);
}
mhash_deinit(td, hash);
printf("Hash:");
for (i = 0; i < mhash_get_block_size(MHASH_MD5); i++) {
printf("%.2x", hash[i]);
}
printf("\n");
exit(0);
}
EXAMPLE¶
An example program using HMAC:
#include <mhash.h>
#include <stdio.h>
int main()
{
char password[] = "Jefe";
int keylen = 4;
char data[] = "what do ya want for nothing?";
int datalen = 28;
MHASH td;
unsigned char mac[16];
int j;
td = mhash_hmac_init(MHASH_MD5, password, keylen,
mhash_get_hash_pblock(MHASH_MD5));
mhash(td, data, datalen);
mhash_hmac_deinit(td, mac);
/*
* The output should be 0x750c783e6ab0b503eaa86e310a5db738
* according to RFC 2104.
*/
printf("0x");
for (j = 0; j < mhash_get_block_size(MHASH_MD5); j++) {
printf("%.2x", mac[j]);
}
printf("\n");
exit(0);
}
HISTORY¶
This library was originally written by
Nikos Mavroyanopoulos
<nmav@hellug.gr> who passed the project over to
Sascha Schumann
<sascha@schumann.cx> in May 1999. Sascha maintained it until March 2000.
The library is now maintained by
Nikos Mavroyanopoulos.
BUGS¶
If you find any, please send a bug report (preferrably together with a patch) to
the maintainer with a detailed description on how to reproduce the bug.
AUTHORS¶
Sascha Schumann <sascha@schumann.cx> Nikos Mavroyanopoulos
<nmav@hellug.gr>