1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* LibTomCrypt, modular cryptographic library -- Tom St Denis 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 3f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * LibTomCrypt is a library that provides various cryptographic 4f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * algorithms in a highly modular and flexible manner. 5f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 6f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library is free for all purposes without any express 7f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * guarantee it works. 8f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 9f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com 10f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 11f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @file ocb_decrypt_verify_memory.c 14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project OCB implementation, helper to decrypt block of memory, by Tom St Denis 15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include "tomcrypt.h" 17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef OCB_MODE 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project Decrypt and compare the tag with OCB. 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param cipher The index of the cipher desired 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param key The secret key 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param keylen The length of the secret key (octets) 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param nonce The session nonce (length of the block size of the block cipher) 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param ct The ciphertext 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param ctlen The length of the ciphertext (octets) 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param pt [out] The plaintext 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param tag The tag to compare against 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param taglen The length of the tag (octets) 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param stat [out] The result of the tag comparison (1==valid, 0==invalid) 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @return CRYPT_OK if successful regardless of the tag comparison 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint ocb_decrypt_verify_memory(int cipher, 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *key, unsigned long keylen, 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *nonce, 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *ct, unsigned long ctlen, 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project unsigned char *pt, 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *tag, unsigned long taglen, 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int *stat) 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int err; 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ocb_state *ocb; 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(key != NULL); 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(nonce != NULL); 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(pt != NULL); 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(ct != NULL); 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(tag != NULL); 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(stat != NULL); 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* allocate memory */ 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ocb = XMALLOC(sizeof(ocb_state)); 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (ocb == NULL) { 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return CRYPT_MEM; 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = ocb_init(ocb, cipher, key, keylen, nonce)) != CRYPT_OK) { 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto LBL_ERR; 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project while (ctlen > (unsigned long)ocb->block_len) { 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = ocb_decrypt(ocb, ct, pt)) != CRYPT_OK) { 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project goto LBL_ERR; 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctlen -= ocb->block_len; 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project pt += ocb->block_len; 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ct += ocb->block_len; 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project err = ocb_done_decrypt(ocb, ct, ctlen, pt, tag, taglen, stat); 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source ProjectLBL_ERR: 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef LTC_CLEAN_STACK 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project zeromem(ocb, sizeof(ocb_state)); 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project XFREE(ocb); 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 82f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 83f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 84f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtomcrypt/src/encauth/ocb/ocb_decrypt_verify_memory.c,v $ */ 85f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.4 $ */ 86f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:15:35 $ */ 87