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comparison src/encauth/ocb/ocb_encrypt.c @ 191:1c15b283127b libtomcrypt-orig

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Import of libtomcrypt 1.02 with manual path rename rearrangement etc
author Matt Johnston <matt@ucc.asn.au>
date Fri, 06 May 2005 13:23:02 +0000
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children 39d5d58461d6
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143:5d99163f7e32 191:1c15b283127b
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, [email protected], http://libtomcrypt.org
10 */
11
12 /**
13 @file ocb_encrypt.c
14 OCB implementation, encrypt data, by Tom St Denis
15 */
16 #include "tomcrypt.h"
17
18 #ifdef OCB_MODE
19
20 /**
21 Encrypt a block of data with OCB.
22 @param ocb The OCB state
23 @param pt The plaintext (length of the block size of the block cipher)
24 @param ct [out] The ciphertext (same size as the pt)
25 @return CRYPT_OK if successful
26 */
27 int ocb_encrypt(ocb_state *ocb, const unsigned char *pt, unsigned char *ct)
28 {
29 unsigned char Z[MAXBLOCKSIZE], tmp[MAXBLOCKSIZE];
30 int err, x;
31
32 LTC_ARGCHK(ocb != NULL);
33 LTC_ARGCHK(pt != NULL);
34 LTC_ARGCHK(ct != NULL);
35 if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
36 return err;
37 }
38 if (ocb->block_len != cipher_descriptor[ocb->cipher].block_length) {
39 return CRYPT_INVALID_ARG;
40 }
41
42 /* compute checksum */
43 for (x = 0; x < ocb->block_len; x++) {
44 ocb->checksum[x] ^= pt[x];
45 }
46
47 /* Get Z[i] value */
48 ocb_shift_xor(ocb, Z);
49
50 /* xor pt in, encrypt, xor Z out */
51 for (x = 0; x < ocb->block_len; x++) {
52 tmp[x] = pt[x] ^ Z[x];
53 }
54 cipher_descriptor[ocb->cipher].ecb_encrypt(tmp, ct, &ocb->key);
55 for (x = 0; x < ocb->block_len; x++) {
56 ct[x] ^= Z[x];
57 }
58
59 #ifdef LTC_CLEAN_STACK
60 zeromem(Z, sizeof(Z));
61 zeromem(tmp, sizeof(tmp));
62 #endif
63 return CRYPT_OK;
64 }
65
66 #endif