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comparison src/mac/omac/omac_done.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 #include "tomcrypt.h"
12
13 /**
14 @file omac_done.c
15 OMAC1 support, terminate a stream, Tom St Denis
16 */
17
18 #ifdef OMAC
19
20 /**
21 Terminate an OMAC stream
22 @param omac The OMAC state
23 @param out [out] Destination for the authentication tag
24 @param outlen [in/out] The max size and resulting size of the authentication tag
25 @return CRYPT_OK if successful
26 */
27 int omac_done(omac_state *omac, unsigned char *out, unsigned long *outlen)
28 {
29 int err, mode;
30 unsigned x;
31
32 LTC_ARGCHK(omac != NULL);
33 LTC_ARGCHK(out != NULL);
34 LTC_ARGCHK(outlen != NULL);
35 if ((err = cipher_is_valid(omac->cipher_idx)) != CRYPT_OK) {
36 return err;
37 }
38
39 if ((omac->buflen > (int)sizeof(omac->block)) || (omac->buflen < 0) ||
40 (omac->blklen > (int)sizeof(omac->block)) || (omac->buflen > omac->blklen)) {
41 return CRYPT_INVALID_ARG;
42 }
43
44 /* figure out mode */
45 if (omac->buflen != omac->blklen) {
46 /* add the 0x80 byte */
47 omac->block[omac->buflen++] = 0x80;
48
49 /* pad with 0x00 */
50 while (omac->buflen < omac->blklen) {
51 omac->block[omac->buflen++] = 0x00;
52 }
53 mode = 1;
54 } else {
55 mode = 0;
56 }
57
58 /* now xor prev + Lu[mode] */
59 for (x = 0; x < (unsigned)omac->blklen; x++) {
60 omac->block[x] ^= omac->prev[x] ^ omac->Lu[mode][x];
61 }
62
63 /* encrypt it */
64 cipher_descriptor[omac->cipher_idx].ecb_encrypt(omac->block, omac->block, &omac->key);
65 cipher_descriptor[omac->cipher_idx].done(&omac->key);
66
67 /* output it */
68 for (x = 0; x < (unsigned)omac->blklen && x < *outlen; x++) {
69 out[x] = omac->block[x];
70 }
71 *outlen = x;
72
73 #ifdef LTC_CLEAN_STACK
74 zeromem(omac, sizeof(*omac));
75 #endif
76 return CRYPT_OK;
77 }
78
79 #endif
80