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