| /* 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_decrypt_verify_memory(int cipher, |
| const unsigned char *key, unsigned long keylen, |
| const unsigned char *nonce, |
| const unsigned char *ct, unsigned long ctlen, |
| unsigned char *pt, |
| const unsigned char *tag, unsigned long taglen, |
| int *res) |
| { |
| int err; |
| ocb_state *ocb; |
| |
| _ARGCHK(key != NULL); |
| _ARGCHK(nonce != NULL); |
| _ARGCHK(pt != NULL); |
| _ARGCHK(ct != NULL); |
| _ARGCHK(tag != NULL); |
| _ARGCHK(res != NULL); |
| |
| /* allocate memory */ |
| ocb = XMALLOC(sizeof(ocb_state)); |
| if (ocb == NULL) { |
| return CRYPT_MEM; |
| } |
| |
| if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) { |
| goto __ERR; |
| } |
| |
| while (ctlen > (unsigned long)ocb->block_len) { |
| if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) { |
| goto __ERR; |
| } |
| ctlen -= ocb->block_len; |
| pt += ocb->block_len; |
| ct += ocb->block_len; |
| } |
| |
| err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, res); |
| __ERR: |
| #ifdef CLEAN_STACK |
| zeromem(ocb, sizeof(ocb_state)); |
| #endif |
| |
| XFREE(ocb); |
| |
| return err; |
| } |
| |
| #endif |