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
11 /**
12 @file ocb3_encrypt.c
13 OCB implementation, encrypt data, by Tom St Denis
14 */
15 #include "tomcrypt_private.h"
16
17 #ifdef LTC_OCB3_MODE
18
19 /**
20 Encrypt blocks of data with OCB
21 @param ocb The OCB state
22 @param pt The plaintext (length multiple of the block size of the block cipher)
23 @param ptlen The length of the input (octets)
24 @param ct [out] The ciphertext (same size as the pt)
25 @return CRYPT_OK if successful
26 */
ocb3_encrypt(ocb3_state * ocb,const unsigned char * pt,unsigned long ptlen,unsigned char * ct)27 int ocb3_encrypt(ocb3_state *ocb, const unsigned char *pt, unsigned long ptlen, unsigned char *ct)
28 {
29 unsigned char tmp[MAXBLOCKSIZE];
30 int err, i, full_blocks;
31 unsigned char *pt_b, *ct_b;
32
33 LTC_ARGCHK(ocb != NULL);
34 if (ptlen == 0) return CRYPT_OK; /* no data, nothing to do */
35 LTC_ARGCHK(pt != NULL);
36 LTC_ARGCHK(ct != NULL);
37
38 if ((err = cipher_is_valid(ocb->cipher)) != CRYPT_OK) {
39 return err;
40 }
41 if (ocb->block_len != cipher_descriptor[ocb->cipher]->block_length) {
42 return CRYPT_INVALID_ARG;
43 }
44
45 if (ptlen % ocb->block_len) { /* ptlen has to bu multiple of block_len */
46 return CRYPT_INVALID_ARG;
47 }
48
49 full_blocks = ptlen/ocb->block_len;
50 for(i=0; i<full_blocks; i++) {
51 pt_b = (unsigned char *)pt+i*ocb->block_len;
52 ct_b = (unsigned char *)ct+i*ocb->block_len;
53
54 /* ocb->Offset_current[] = ocb->Offset_current[] ^ Offset_{ntz(block_index)} */
55 ocb3_int_xor_blocks(ocb->Offset_current, ocb->Offset_current, ocb->L_[ocb3_int_ntz(ocb->block_index)], ocb->block_len);
56
57 /* tmp[] = pt[] XOR ocb->Offset_current[] */
58 ocb3_int_xor_blocks(tmp, pt_b, ocb->Offset_current, ocb->block_len);
59
60 /* encrypt */
61 if ((err = cipher_descriptor[ocb->cipher]->ecb_encrypt(tmp, tmp, &ocb->key)) != CRYPT_OK) {
62 goto LBL_ERR;
63 }
64
65 /* ct[] = tmp[] XOR ocb->Offset_current[] */
66 ocb3_int_xor_blocks(ct_b, tmp, ocb->Offset_current, ocb->block_len);
67
68 /* ocb->checksum[] = ocb->checksum[] XOR pt[] */
69 ocb3_int_xor_blocks(ocb->checksum, ocb->checksum, pt_b, ocb->block_len);
70
71 ocb->block_index++;
72 }
73
74 err = CRYPT_OK;
75
76 LBL_ERR:
77 #ifdef LTC_CLEAN_STACK
78 zeromem(tmp, sizeof(tmp));
79 #endif
80 return err;
81 }
82
83 #endif
84
85 /* ref: $Format:%D$ */
86 /* git commit: $Format:%H$ */
87 /* commit time: $Format:%ai$ */
88