| /* 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 OFB |
| |
| int 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 |