hmac.c

来自「文件驱动加密,功能强大,可产生加密分区,支持AES,MD2,MD4,MD5MD2」· C语言 代码 · 共 525 行 · 第 1/2 页

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * gurantee it works.
 *
 * Tom St Denis, [e-mail], http://libtomcrypt.org
 */
/* Submited by Dobes Vandermeer  ([e-mail]) */

#include "mycrypt.h"

/*
    (1) append zeros to the end of K to create a B byte string
        (e.g., if K is of length 20 bytes and B=64, then K will be
         appended with 44 zero bytes 0x00)
    (2) XOR (bitwise exclusive-OR) the B byte string computed in step
        (1) with ipad (ipad = the byte 0x36 repeated B times)
    (3) append the stream of data 'text' to the B byte string resulting
        from step (2)
    (4) apply H to the stream generated in step (3)
    (5) XOR (bitwise exclusive-OR) the B byte string computed in
        step (1) with opad (opad = the byte 0x5C repeated B times.)
    (6) append the H result from step (4) to the B byte string
        resulting from step (5)
    (7) apply H to the stream generated in step (6) and output
        the result
*/

#ifdef HMAC

#define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize

int hmac_init(hmac_state *hmac, int hash, const unsigned char *key, unsigned long keylen)
{
    unsigned char buf[MAXBLOCKSIZE];
    unsigned long hashsize;
    unsigned long i, z;
    int err;

    _ARGCHK(hmac != NULL);
    _ARGCHK(key != NULL);

    if ((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }

    /* valid key length? */
    if (keylen == 0) {
        return CRYPT_INVALID_KEYSIZE;
    }

    hmac->hash = hash;

    // (1) make sure we have a large enough key
    hashsize = hash_descriptor[hash].hashsize;
    if(keylen > HMAC_BLOCKSIZE) {
        z = (unsigned long)sizeof(hmac->key);
        if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) {
           return err;
        }
        if(hashsize < HMAC_BLOCKSIZE) {
            zeromem((hmac->key) + hashsize, (size_t)(HMAC_BLOCKSIZE - hashsize));
        }
        keylen = hashsize;
    } else {
        memcpy(hmac->key, key, (size_t)keylen);
        if(keylen < HMAC_BLOCKSIZE) {
            zeromem((hmac->key) + keylen, (size_t)(HMAC_BLOCKSIZE - keylen));
        }
    }

    // Create the initial vector for step (3)
    for(i=0; i < HMAC_BLOCKSIZE;   i++) {
       buf[i] = hmac->key[i] ^ 0x36;
    }

    // Pre-pend that to the hash data
    hash_descriptor[hash].init(&hmac->md);
    hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE);

    return CRYPT_OK;
}

int hmac_process(hmac_state *hmac, const unsigned char *buf, unsigned long len)
{
    int err;
    _ARGCHK(hmac != NULL);
    _ARGCHK(buf != NULL);
    if ((err = hash_is_valid(hmac->hash)) != CRYPT_OK) {
        return err;
    }
    return hash_descriptor[hmac->hash].process(&hmac->md, buf, len);
}

int hmac_done(hmac_state *hmac, unsigned char *hashOut, unsigned long *outlen)
{
    unsigned char buf[MAXBLOCKSIZE];
    unsigned char isha[MAXBLOCKSIZE];
    unsigned long hashsize, i;
    int hash, err;

    _ARGCHK(hmac != NULL);
    _ARGCHK(hashOut != NULL);

    hash = hmac->hash;
    if((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }

    /* get the hash message digest size */
    hashsize = hash_descriptor[hash].hashsize;

    // Get the hash of the first HMAC vector plus the data
    if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
       return err;
    }

    // Create the second HMAC vector vector for step (3)
    for(i=0; i < HMAC_BLOCKSIZE; i++) {
        buf[i] = hmac->key[i] ^ 0x5C;
    }

    // Now calculate the "outer" hash for step (5), (6), and (7)
    hash_descriptor[hash].init(&hmac->md);
    hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE);
    hash_descriptor[hash].process(&hmac->md, isha, hashsize);
    hash_descriptor[hash].done(&hmac->md, buf);

    // copy to output 
    for (i = 0; i < hashsize && i < *outlen; i++) {
        hashOut[i] = buf[i];
    }
    *outlen = i;

#ifdef CLEAN_STACK
    zeromem(isha, sizeof(buf));
    zeromem(buf,  sizeof(isha));
    zeromem(hmac, sizeof(*hmac));
#endif
    return CRYPT_OK;
}

int hmac_memory(int hash, const unsigned char *key, unsigned long keylen,
                const unsigned char *data, unsigned long len, 
                unsigned char *dst, unsigned long *dstlen)
{
    hmac_state hmac;
    int err;

    _ARGCHK(key    != NULL);
    _ARGCHK(data   != NULL);
    _ARGCHK(dst    != NULL); 
    _ARGCHK(dstlen != NULL);
    
    if((err = hash_is_valid(hash)) != CRYPT_OK) {
        return err;
    }

    if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
        return err;
    }

    if ((err = hmac_process(&hmac, data, len)) != CRYPT_OK) {
       return err;
    }

    if ((err = hmac_done(&hmac, dst, dstlen)) != CRYPT_OK) {
       return err;
    }
    return CRYPT_OK;
}

/* hmac_file added by Tom St Denis */
int hmac_file(int hash, const char *fname, 
              const unsigned char *key, unsigned long keylen, 
                    unsigned char *dst, unsigned long *dstlen)
{
#ifdef NO_FILE
    return CRYPT_NOP;
#else
   hmac_state hmac;
   FILE *in;
   unsigned char buf[512];
   size_t x;
   int err;

   _ARGCHK(fname  != NULL);
   _ARGCHK(key    != NULL);
   _ARGCHK(dst    != NULL);
   _ARGCHK(dstlen != NULL);
   
   if((err = hash_is_valid(hash)) != CRYPT_OK) {
       return err;
   }

   if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
       return err;
   }

   in = fopen(fname, "rb");
   if (in == NULL) {
      return CRYPT_FILE_NOTFOUND;
   }

   /* process the file contents */
   do {
      x = fread(buf, 1, sizeof(buf), in);
      if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) {
         /* we don't trap this error since we're already returning an error! */
         fclose(in);
         return err;
      }
   } while (x == sizeof(buf));

   if (fclose(in) != 0) {
      return CRYPT_ERROR;
   }

   /* get final hmac */
   if ((err = hmac_done(&hmac, dst, dstlen)) != CRYPT_OK) {
      return err;
   }

#ifdef CLEAN_STACK
   /* clear memory */
   zeromem(buf, sizeof(buf));
#endif   
   return CRYPT_OK;
#endif
}

/*

    TEST CASES SOURCE:

Network Working Group                                          P. Cheng
Request for Comments: 2202                                          IBM
Category: Informational                                        R. Glenn
                                                                   NIST
                                                         September 1997

                 Test Cases for HMAC-MD5 and HMAC-SHA-1
*/


int hmac_test(void)
{
 #ifndef LTC_TEST
    return CRYPT_NOP;
 #else    
    unsigned char digest[MAXBLOCKSIZE];
    int i;

    static const struct hmac_test_case {
        int num;
        char *algo;
        unsigned char key[128];
        unsigned long keylen;
        unsigned char data[128];
        unsigned long datalen;