1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis */
2 /* SPDX-License-Identifier: Unlicense */
3 #include "tomcrypt_private.h"
4
5 /**
6 @file ofb_start.c
7 OFB implementation, start chain, Tom St Denis
8 */
9
10
11 #ifdef LTC_OFB_MODE
12
13 /**
14 Initialize a OFB context
15 @param cipher The index of the cipher desired
16 @param IV The initialization vector
17 @param key The secret key
18 @param keylen The length of the secret key (octets)
19 @param num_rounds Number of rounds in the cipher desired (0 for default)
20 @param ofb The OFB state to initialize
21 @return CRYPT_OK if successful
22 */
ofb_start(int cipher,const unsigned char * IV,const unsigned char * key,int keylen,int num_rounds,symmetric_OFB * ofb)23 int ofb_start(int cipher, const unsigned char *IV, const unsigned char *key,
24 int keylen, int num_rounds, symmetric_OFB *ofb)
25 {
26 int x, err;
27
28 LTC_ARGCHK(IV != NULL);
29 LTC_ARGCHK(key != NULL);
30 LTC_ARGCHK(ofb != NULL);
31
32 if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
33 return err;
34 }
35
36 /* copy details */
37 ofb->cipher = cipher;
38 ofb->blocklen = cipher_descriptor[cipher]->block_length;
39 for (x = 0; x < ofb->blocklen; x++) {
40 ofb->IV[x] = IV[x];
41 }
42
43 /* init the cipher */
44 ofb->padlen = ofb->blocklen;
45 return cipher_descriptor[cipher]->setup(key, keylen, num_rounds, &ofb->key);
46 }
47
48 #endif
49