1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
|
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
*/
#include "tomcrypt.h"
/**
@file hmac_done.c
HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer
*/
#ifdef LTC_HMAC
#define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
/**
Terminate an HMAC session
@param hmac The HMAC state
@param out [out] The destination of the HMAC authentication tag
@param outlen [in/out] The max size and resulting size of the HMAC authentication tag
@return CRYPT_OK if successful
*/
int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen)
{
unsigned char *buf, *isha;
unsigned long hashsize, i;
int hash, err;
LTC_ARGCHK(hmac != NULL);
LTC_ARGCHK(out != NULL);
/* test hash */
hash = hmac->hash;
if((err = hash_is_valid(hash)) != CRYPT_OK) {
return err;
}
/* get the hash message digest size */
hashsize = hash_descriptor[hash].hashsize;
/* allocate buffers */
buf = XMALLOC(HMAC_BLOCKSIZE);
isha = XMALLOC(hashsize);
if (buf == NULL || isha == NULL) {
if (buf != NULL) {
XFREE(buf);
}
if (isha != NULL) {
XFREE(isha);
}
return CRYPT_MEM;
}
/* Get the hash of the first HMAC vector plus the data */
if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
goto LBL_ERR;
}
/* Create the second HMAC vector vector for step (3) */
for(i=0; i < HMAC_BLOCKSIZE; i++) {
buf[i] = hmac->key[i] ^ 0x5C;
}
/* Now calculate the "outer" hash for step (5), (6), and (7) */
if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) {
goto LBL_ERR;
}
/* copy to output */
for (i = 0; i < hashsize && i < *outlen; i++) {
out[i] = buf[i];
}
*outlen = i;
err = CRYPT_OK;
LBL_ERR:
XFREE(hmac->key);
#ifdef LTC_CLEAN_STACK
zeromem(isha, hashsize);
zeromem(buf, hashsize);
zeromem(hmac, sizeof(*hmac));
#endif
XFREE(isha);
XFREE(buf);
return err;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_done.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/11/03 00:39:49 $ */
|
