/* 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 *//* OMAC1 Support by Tom St Denis (for 64 and 128 bit block ciphers only) */#include "mycrypt.h"#ifdef OMACint omac_process(omac_state *state, const unsigned char *buf, unsigned long len){   int err, n, x;   _ARGCHK(state != NULL);   _ARGCHK(buf   != NULL);   if ((err = cipher_is_valid(state->cipher_idx)) != CRYPT_OK) {      return err;   }   if ((state->buflen > (int)sizeof(state->block)) || (state->buflen < 0) ||       (state->blklen > (int)sizeof(state->block)) || (state->buflen > state->blklen)) {      return CRYPT_INVALID_ARG;   }   while (len != 0) {        /* ok if the block is full we xor in prev, encrypt and replace prev */       if (state->buflen == state->blklen) {          for (x = 0; x < state->blklen; x++) {              state->block[x] ^= state->prev[x];          }          cipher_descriptor[state->cipher_idx].ecb_encrypt(state->block, state->prev, &state->key);          state->buflen = 0;       }       /* add bytes */       n = MIN(len, (unsigned long)(state->blklen - state->buflen));       memcpy(state->block + state->buflen, buf, n);       state->buflen += n;       len           -= n;       buf           += n;   }   return CRYPT_OK;}#endif