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 * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
10 */
11 #include "tomcrypt.h"
12
13 /**
14 @file ofb_encrypt.c
15 OFB implementation, encrypt data, Tom St Denis
16 */
17
18 #ifdef LTC_OFB_MODE
19
20 /**
21 OFB encrypt
22 @param pt Plaintext
23 @param ct [out] Ciphertext
24 @param len Length of plaintext (octets)
25 @param ofb OFB state
26 @return CRYPT_OK if successful
27 */
ofb_encrypt(const unsigned char * pt,unsigned char * ct,unsigned long len,symmetric_OFB * ofb)28 int ofb_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_OFB *ofb)
29 {
30 int err;
31 LTC_ARGCHK(pt != NULL);
32 LTC_ARGCHK(ct != NULL);
33 LTC_ARGCHK(ofb != NULL);
34 if ((err = cipher_is_valid(ofb->cipher)) != CRYPT_OK) {
35 return err;
36 }
37
38 /* is blocklen/padlen valid? */
39 if (ofb->blocklen < 0 || ofb->blocklen > (int)sizeof(ofb->IV) ||
40 ofb->padlen < 0 || ofb->padlen > (int)sizeof(ofb->IV)) {
41 return CRYPT_INVALID_ARG;
42 }
43
44 while (len-- > 0) {
45 if (ofb->padlen == ofb->blocklen) {
46 if ((err = cipher_descriptor[ofb->cipher].ecb_encrypt(ofb->IV, ofb->IV, &ofb->key)) != CRYPT_OK) {
47 return err;
48 }
49 ofb->padlen = 0;
50 }
51 *ct++ = *pt++ ^ ofb->IV[(ofb->padlen)++];
52 }
53 return CRYPT_OK;
54 }
55
56 #endif
57
58 /* $Source: /cvs/libtom/libtomcrypt/src/modes/ofb/ofb_encrypt.c,v $ */
59 /* $Revision: 1.7 $ */
60 /* $Date: 2006/11/26 01:45:14 $ */
61