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 omac_done.c
14 OMAC1 support, terminate a stream, Tom St Denis
15 */
16
17 #ifdef LTC_OMAC
18
19 /**
20 Terminate an OMAC stream
21 @param omac The OMAC state
22 @param out [out] Destination for the authentication tag
23 @param outlen [in/out] The max size and resulting size of the authentication tag
24 @return CRYPT_OK if successful
25 */
omac_done(omac_state * omac,unsigned char * out,unsigned long * outlen)26 int omac_done(omac_state *omac, unsigned char *out, unsigned long *outlen)
27 {
28 int err, mode;
29 unsigned x;
30
31 LTC_ARGCHK(omac != NULL);
32 LTC_ARGCHK(out != NULL);
33 LTC_ARGCHK(outlen != NULL);
34 if ((err = cipher_is_valid(omac->cipher_idx)) != CRYPT_OK) {
35 return err;
36 }
37
38 if ((omac->buflen > (int)sizeof(omac->block)) || (omac->buflen < 0) ||
39 (omac->blklen > (int)sizeof(omac->block)) || (omac->buflen > omac->blklen)) {
40 return CRYPT_INVALID_ARG;
41 }
42
43 /* figure out mode */
44 if (omac->buflen != omac->blklen) {
45 /* add the 0x80 byte */
46 omac->block[omac->buflen++] = 0x80;
47
48 /* pad with 0x00 */
49 while (omac->buflen < omac->blklen) {
50 omac->block[omac->buflen++] = 0x00;
51 }
52 mode = 1;
53 } else {
54 mode = 0;
55 }
56
57 /* now xor prev + Lu[mode] */
58 for (x = 0; x < (unsigned)omac->blklen; x++) {
59 omac->block[x] ^= omac->prev[x] ^ omac->Lu[mode][x];
60 }
61
62 /* encrypt it */
63 if ((err = cipher_descriptor[omac->cipher_idx]->ecb_encrypt(omac->block, omac->block, &omac->key)) != CRYPT_OK) {
64 return err;
65 }
66 cipher_descriptor[omac->cipher_idx]->done(&omac->key);
67
68 /* output it */
69 for (x = 0; x < (unsigned)omac->blklen && x < *outlen; x++) {
70 out[x] = omac->block[x];
71 }
72 *outlen = x;
73
74 #ifdef LTC_CLEAN_STACK
75 zeromem(omac, sizeof(*omac));
76 #endif
77 return CRYPT_OK;
78 }
79
80 #endif
81
82
83 /* ref: $Format:%D$ */
84 /* git commit: $Format:%H$ */
85 /* commit time: $Format:%ai$ */
86