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