/* 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 * guarantee it works. * * Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org *//* Submited by Dobes Vandermeer  (dobes@smartt.com) */#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/* 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}#endif