1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 *
9 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file ecb_decrypt.c
15 ECB implementation, decrypt a block, Tom St Denis
16 */
17
18 #ifdef LTC_ECB_MODE
19
20 /**
21 ECB decrypt
22 @param ct Ciphertext
23 @param pt [out] Plaintext
24 @param len The number of octets to process (must be multiple of the cipher block size)
25 @param ecb ECB state
26 @return CRYPT_OK if successful
27 */
ecb_decrypt(const unsigned char * ct,unsigned char * pt,unsigned long len,symmetric_ECB * ecb)28 int ecb_decrypt(const unsigned char *ct, unsigned char *pt, unsigned long len, symmetric_ECB *ecb)
29 {
30 int err;
31 LTC_ARGCHK(pt != NULL);
32 LTC_ARGCHK(ct != NULL);
33 LTC_ARGCHK(ecb != NULL);
34 if ((err = cipher_is_valid(ecb->cipher)) != CRYPT_OK) {
35 return err;
36 }
37 if (len % cipher_descriptor[ecb->cipher].block_length) {
38 return CRYPT_INVALID_ARG;
39 }
40
41 /* check for accel */
42 if (cipher_descriptor[ecb->cipher].accel_ecb_decrypt != NULL) {
43 return cipher_descriptor[ecb->cipher].accel_ecb_decrypt(ct, pt, len / cipher_descriptor[ecb->cipher].block_length, &ecb->key);
44 } else {
45 while (len) {
46 if ((err = cipher_descriptor[ecb->cipher].ecb_decrypt(ct, pt, &ecb->key)) != CRYPT_OK) {
47 return err;
48 }
49 pt += cipher_descriptor[ecb->cipher].block_length;
50 ct += cipher_descriptor[ecb->cipher].block_length;
51 len -= cipher_descriptor[ecb->cipher].block_length;
52 }
53 }
54 return CRYPT_OK;
55 }
56
57 #endif
58
59 /* $Source: /cvs/libtom/libtomcrypt/src/modes/ecb/ecb_decrypt.c,v $ */
60 /* $Revision: 1.9 $ */
61 /* $Date: 2006/06/29 01:51:34 $ */
62