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 #include "tomcrypt.h"
10
11 /**
12 @file ofb_encrypt.c
13 OFB implementation, encrypt data, Tom St Denis
14 */
15
16 #ifdef LTC_OFB_MODE
17
18 /**
19 OFB encrypt
20 @param pt Plaintext
21 @param ct [out] Ciphertext
22 @param len Length of plaintext (octets)
23 @param ofb OFB state
24 @return CRYPT_OK if successful
25 */
ofb_encrypt(const unsigned char * pt,unsigned char * ct,unsigned long len,symmetric_OFB * ofb)26 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
27 {
28 int err;
29 LTC_ARGCHK(pt != NULL);
30 LTC_ARGCHK(ct != NULL);
31 LTC_ARGCHK(ofb != NULL);
32 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
33 return err;
34 }
35
36 /* is blocklen/padlen valid? */
37 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
38 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
39 return CRYPT_INVALID_ARG;
40 }
41
42 while (len-- > 0) {
43 if (ofb->padlen == ofb->blocklen) {
44 if ((err = cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key)) != CRYPT_OK) {
45 return err;
46 }
47 ofb->padlen = 0;
48 }
49 *ct++ = *pt++ ^ ofb->IV[(ofb->padlen)++];
50 }
51 return CRYPT_OK;
52 }
53
54 #endif
55
56 /* ref: $Format:%D$ */
57 /* git commit: $Format:%H$ */
58 /* commit time: $Format:%ai$ */
59