| /* 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 |
| */ |
| |
| /* OCB Implementation by Tom St Denis */ |
| #include "mycrypt.h" |
| |
| #ifdef OCB_MODE |
| |
| int ocb_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned char *ct) |
| { |
| unsigned char Z[MAXBLOCKSIZE], tmp[MAXBLOCKSIZE]; |
| int err, x; |
| |
| _ARGCHK(ocb != NULL); |
| _ARGCHK(pt != NULL); |
| _ARGCHK(ct != NULL); |
| if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) { |
| return err; |
| } |
| if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length) { |
| return CRYPT_INVALID_ARG; |
| } |
| |
| /* compute checksum */ |
| for (x = 0; x < ocb->block_len; x++) { |
| ocb->checksum[x] ^= pt[x]; |
| } |
| |
| /* Get Z[i] value */ |
| ocb_shift_xor(ocb, Z); |
| |
| /* xor pt in, encrypt, xor Z out */ |
| for (x = 0; x < ocb->block_len; x++) { |
| tmp[x] = pt[x] ^ Z[x]; |
| } |
| cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, ct, &ocb->key); |
| for (x = 0; x < ocb->block_len; x++) { |
| ct[x] ^= Z[x]; |
| } |
| |
| #ifdef CLEAN_STACK |
| zeromem(Z, sizeof(Z)); |
| zeromem(tmp, sizeof(tmp)); |
| #endif |
| return CRYPT_OK; |
| } |
| |
| #endif |