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comparison libtomcrypt/src/mac/hmac/hmac_done.c @ 285:1b9e69c058d2

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propagate from branch 'au.asn.ucc.matt.ltc.dropbear' (head 20dccfc09627970a312d77fb41dc2970b62689c3) to branch 'au.asn.ucc.matt.dropbear' (head fdf4a7a3b97ae5046139915de7e40399cceb2c01)
author Matt Johnston <matt@ucc.asn.au>
date Wed, 08 Mar 2006 13:23:58 +0000
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children 0cbe8f6dbf9e
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281:997e6f7dc01e 285:1b9e69c058d2
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 hmac_done.c
15 HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer
16 */
17
18 #ifdef HMAC
19
20 #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
21
22 /**
23 Terminate an HMAC session
24 @param hmac The HMAC state
25 @param out [out] The destination of the HMAC authentication tag
26 @param outlen [in/out] The max size and resulting size of the HMAC authentication tag
27 @return CRYPT_OK if successful
28 */
29 int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen)
30 {
31 unsigned char *buf, *isha;
32 unsigned long hashsize, i;
33 int hash, err;
34
35 LTC_ARGCHK(hmac != NULL);
36 LTC_ARGCHK(out != NULL);
37
38 /* test hash */
39 hash = hmac->hash;
40 if((err = hash_is_valid(hash)) != CRYPT_OK) {
41 return err;
42 }
43
44 /* get the hash message digest size */
45 hashsize = hash_descriptor[hash].hashsize;
46
47 /* allocate buffers */
48 buf = XMALLOC(HMAC_BLOCKSIZE);
49 isha = XMALLOC(hashsize);
50 if (buf == NULL || isha == NULL) {
51 if (buf != NULL) {
52 XFREE(buf);
53 }
54 if (isha != NULL) {
55 XFREE(isha);
56 }
57 return CRYPT_MEM;
58 }
59
60 /* Get the hash of the first HMAC vector plus the data */
61 if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
62 goto LBL_ERR;
63 }
64
65 /* Create the second HMAC vector vector for step (3) */
66 for(i=0; i < HMAC_BLOCKSIZE; i++) {
67 buf[i] = hmac->key[i] ^ 0x5C;
68 }
69
70 /* Now calculate the "outer" hash for step (5), (6), and (7) */
71 if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) {
72 goto LBL_ERR;
73 }
74 if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) {
75 goto LBL_ERR;
76 }
77 if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) {
78 goto LBL_ERR;
79 }
80 if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) {
81 goto LBL_ERR;
82 }
83
84 /* copy to output */
85 for (i = 0; i < hashsize && i < *outlen; i++) {
86 out[i] = buf[i];
87 }
88 *outlen = i;
89
90 err = CRYPT_OK;
91 LBL_ERR:
92 XFREE(hmac->key);
93 #ifdef LTC_CLEAN_STACK
94 zeromem(isha, hashsize);
95 zeromem(buf, hashsize);
96 zeromem(hmac, sizeof(*hmac));
97 #endif
98
99 XFREE(isha);
100 XFREE(buf);
101
102 return err;
103 }
104
105 #endif
106
107 /* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_done.c,v $ */
108 /* $Revision: 1.3 $ */
109 /* $Date: 2005/05/05 14:35:58 $ */