/* 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 */#include "mycrypt.h"#ifdef CFBint cfb_start(int cipher, const unsigned char *IV, const unsigned char *key,               int keylen, int num_rounds, symmetric_CFB *cfb){   int x, err;   _ARGCHK(IV != NULL);   _ARGCHK(key != NULL);   _ARGCHK(cfb != NULL);   if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {      return err;   }      /* copy data */   cfb->cipher = cipher;   cfb->blocklen = cipher_descriptor[cipher].block_length;   for (x = 0; x < cfb->blocklen; x++)       cfb->IV[x] = IV[x];   /* init the cipher */   if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &cfb->key)) != CRYPT_OK) {      return err;   }   /* encrypt the IV */   cipher_descriptor[cfb->cipher].ecb_encrypt(cfb->IV, cfb->IV, &cfb->key);   cfb->padlen = 0;   return CRYPT_OK;}#endif