/* 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 OFBint ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb){   int err;   _ARGCHK(pt != NULL);   _ARGCHK(ct != NULL);   _ARGCHK(ofb != NULL);   if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {       return err;   }      /* is blocklen/padlen valid? */   if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||       ofb->padlen   < 0 || ofb->padlen   > (int)sizeof(ofb->IV)) {      return CRYPT_INVALID_ARG;   }      while (len-- > 0) {       if (ofb->padlen == ofb->blocklen) {          cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key);          ofb->padlen = 0;       }       *ct++ = *pt++ ^ ofb->IV[ofb->padlen++];   }   return CRYPT_OK;}#endif