Provided by: libmhash-dev_0.9.9.9-9build2_amd64 bug

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 (preferably 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>