ctr_start.c revision f7fc46c63fdc8f39234fea409b8dbe116d73ebf8
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#include "tomcrypt.h" 12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @file ctr_start.c 15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project CTR implementation, start chain, Tom St Denis 16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef LTC_CTR_MODE 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project Initialize a CTR context 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param cipher The index of the cipher desired 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param IV The initial vector 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param key The secret key 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param keylen The length of the secret key (octets) 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param num_rounds Number of rounds in the cipher desired (0 for default) 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param ctr_mode The counter mode (CTR_COUNTER_LITTLE_ENDIAN or CTR_COUNTER_BIG_ENDIAN) 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param ctr The CTR state to initialize 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @return CRYPT_OK if successful 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint ctr_start( int cipher, 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *IV, 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *key, int keylen, 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int num_rounds, int ctr_mode, 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project symmetric_CTR *ctr) 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int x, err; 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(IV != NULL); 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(key != NULL); 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(ctr != NULL); 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* bad param? */ 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = cipher_is_valid(cipher)) != CRYPT_OK) { 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* setup cipher */ 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = cipher_descriptor[cipher].setup(key, keylen, num_rounds, &ctr->key)) != CRYPT_OK) { 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* copy ctr */ 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->blocklen = cipher_descriptor[cipher].block_length; 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->cipher = cipher; 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->padlen = 0; 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->mode = ctr_mode & 1; 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = 0; x < ctr->blocklen; x++) { 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->ctr[x] = IV[x]; 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (ctr_mode & LTC_CTR_RFC3686) { 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* increment the IV as per RFC 3686 */ 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) { 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* little-endian */ 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = 0; x < ctr->blocklen; x++) { 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (ctr->ctr[x] != (unsigned char)0) { 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project break; 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } else { 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* big-endian */ 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = ctr->blocklen-1; x >= 0; x--) { 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255; 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (ctr->ctr[x] != (unsigned char)0) { 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project break; 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 82f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 83f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 84f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key); 85f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 86f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 87f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif 88f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 89f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtomcrypt/src/modes/ctr/ctr_start.c,v $ */ 90f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.11 $ */ 91f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/11/05 01:46:35 $ */ 92