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_encrypt.c
14 OFB implementation, encrypt data, Tom St Denis
15 */
16
17 #ifdef LTC_OFB_MODE
18
19 /**
20 OFB encrypt
21 @param pt Plaintext
22 @param ct [out] Ciphertext
23 @param len Length of plaintext (octets)
24 @param ofb OFB state
25 @return CRYPT_OK if successful
26 */
ofb_encrypt(const unsigned char * pt,unsigned char * ct,unsigned long len,symmetric_OFB * ofb)27 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
28 {
29 int err;
30 LTC_ARGCHK(pt != NULL);
31 LTC_ARGCHK(ct != NULL);
32 LTC_ARGCHK(ofb != NULL);
33 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
34 return err;
35 }
36
37 /* is blocklen/padlen valid? */
38 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
39 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
40 return CRYPT_INVALID_ARG;
41 }
42
43 while (len-- > 0) {
44 if (ofb->padlen == ofb->blocklen) {
45 if ((err = cipher_descriptor[ofb->cipher]->ecb_encrypt(ofb->IV, ofb->IV, &ofb->key)) != CRYPT_OK) {
46 return err;
47 }
48 ofb->padlen = 0;
49 }
50 *ct++ = *pt++ ^ ofb->IV[(ofb->padlen)++];
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