| /* 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@gmail.com, http://libtomcrypt.com |
| */ |
| |
| /** |
| @file ocb_decrypt_verify_memory.c |
| OCB implementation, helper to decrypt block of memory, by Tom St Denis |
| */ |
| #include "tomcrypt.h" |
| |
| #ifdef OCB_MODE |
| |
| /** |
| Decrypt and compare the tag with OCB. |
| @param cipher The index of the cipher desired |
| @param key The secret key |
| @param keylen The length of the secret key (octets) |
| @param nonce The session nonce (length of the block size of the block cipher) |
| @param ct The ciphertext |
| @param ctlen The length of the ciphertext (octets) |
| @param pt [out] The plaintext |
| @param tag The tag to compare against |
| @param taglen The length of the tag (octets) |
| @param stat [out] The result of the tag comparison (1==valid, 0==invalid) |
| @return CRYPT_OK if successful regardless of the tag comparison |
| */ |
| 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 *stat) |
| { |
| int err; |
| ocb_state *ocb; |
| |
| LTC_ARGCHK(key != NULL); |
| LTC_ARGCHK(nonce != NULL); |
| LTC_ARGCHK(pt != NULL); |
| LTC_ARGCHK(ct != NULL); |
| LTC_ARGCHK(tag != NULL); |
| LTC_ARGCHK(stat != 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 LBL_ERR; |
| } |
| |
| while (ctlen > (unsigned long)ocb->block_len) { |
| if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| ctlen -= ocb->block_len; |
| pt += ocb->block_len; |
| ct += ocb->block_len; |
| } |
| |
| err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, stat); |
| LBL_ERR: |
| #ifdef LTC_CLEAN_STACK |
| zeromem(ocb, sizeof(ocb_state)); |
| #endif |
| |
| XFREE(ocb); |
| |
| return err; |
| } |
| |
| #endif |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/encauth/ocb/ocb_decrypt_verify_memory.c,v $ */ |
| /* $Revision: 1.4 $ */ |
| /* $Date: 2006/03/31 14:15:35 $ */ |