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 ofb_start.c
14 OFB implementation, start chain, Tom St Denis
15 */
16
17
18 #ifdef LTC_OFB_MODE
19
20 /**
21 Initialize a OFB context
22 @param cipher The index of the cipher desired
23 @param IV The initialization vector
24 @param key The secret key
25 @param keylen The length of the secret key (octets)
26 @param num_rounds Number of rounds in the cipher desired (0 for default)
27 @param ofb The OFB state to initialize
28 @return CRYPT_OK if successful
29 */
ofb_start(int cipher,const unsigned char * IV,const unsigned char * key,int keylen,int num_rounds,symmetric_OFB * ofb)30 int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
31 int keylen, int num_rounds, symmetric_OFB *ofb)
32 {
33 int x, err;
34
35 LTC_ARGCHK(IV != NULL);
36 LTC_ARGCHK(key != NULL);
37 LTC_ARGCHK(ofb != NULL);
38
39 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
40 return err;
41 }
42
43 /* copy details */
44 ofb->cipher = cipher;
45 ofb->blocklen = cipher_descriptor[cipher]->block_length;
46 for (x = 0; x < ofb->blocklen; x++) {
47 ofb->IV[x] = IV[x];
48 }
49
50 /* init the cipher */
51 ofb->padlen = ofb->blocklen;
52 return cipher_descriptor[cipher]->setup(key, keylen, num_rounds, &ofb->key);
53 }
54
55 #endif
56
57 /* ref: $Format:%D$ */
58 /* git commit: $Format:%H$ */
59 /* commit time: $Format:%ai$ */
60