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 hmac_done.c
14 HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer
15 */
16
17 #ifdef LTC_HMAC
18
19 #define LTC_HMAC_BLOCKSIZE hash_descriptor[hash]->blocksize
20
21 /**
22 Terminate an HMAC session
23 @param hmac The HMAC state
24 @param out [out] The destination of the HMAC authentication tag
25 @param outlen [in/out] The max size and resulting size of the HMAC authentication tag
26 @return CRYPT_OK if successful
27 */
hmac_done(hmac_state * hmac,unsigned char * out,unsigned long * outlen)28 int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen)
29 {
30 unsigned char *buf, *isha;
31 unsigned long hashsize, i;
32 int hash, err;
33
34 LTC_ARGCHK(hmac != NULL);
35 LTC_ARGCHK(out != NULL);
36
37 /* test hash */
38 hash = hmac->hash;
39 if((err = hash_is_valid(hash)) != CRYPT_OK) {
40 return err;
41 }
42
43 /* get the hash message digest size */
44 hashsize = hash_descriptor[hash]->hashsize;
45
46 /* allocate buffers */
47 buf = XMALLOC(LTC_HMAC_BLOCKSIZE);
48 isha = XMALLOC(hashsize);
49 if (buf == NULL || isha == NULL) {
50 if (buf != NULL) {
51 XFREE(buf);
52 }
53 if (isha != NULL) {
54 XFREE(isha);
55 }
56 return CRYPT_MEM;
57 }
58
59 /* Get the hash of the first HMAC vector plus the data */
60 if ((err = hash_descriptor[hash]->done(&hmac->md, isha)) != CRYPT_OK) {
61 goto LBL_ERR;
62 }
63
64 /* Create the second HMAC vector vector for step (3) */
65 for(i=0; i < LTC_HMAC_BLOCKSIZE; i++) {
66 buf[i] = hmac->key[i] ^ 0x5C;
67 }
68
69 /* Now calculate the "outer" hash for step (5), (6), and (7) */
70 if ((err = hash_descriptor[hash]->init(&hmac->md)) != CRYPT_OK) {
71 goto LBL_ERR;
72 }
73 if ((err = hash_descriptor[hash]->process(&hmac->md, buf, LTC_HMAC_BLOCKSIZE)) != CRYPT_OK) {
74 goto LBL_ERR;
75 }
76 if ((err = hash_descriptor[hash]->process(&hmac->md, isha, hashsize)) != CRYPT_OK) {
77 goto LBL_ERR;
78 }
79 if ((err = hash_descriptor[hash]->done(&hmac->md, buf)) != CRYPT_OK) {
80 goto LBL_ERR;
81 }
82
83 /* copy to output */
84 for (i = 0; i < hashsize && i < *outlen; i++) {
85 out[i] = buf[i];
86 }
87 *outlen = i;
88
89 err = CRYPT_OK;
90 LBL_ERR:
91 #ifdef LTC_CLEAN_STACK
92 zeromem(isha, hashsize);
93 zeromem(buf, hashsize);
94 zeromem(hmac, sizeof(*hmac));
95 #endif
96
97 XFREE(isha);
98 XFREE(buf);
99
100 return err;
101 }
102
103 #endif
104
105 /* ref: $Format:%D$ */
106 /* git commit: $Format:%H$ */
107 /* commit time: $Format:%ai$ */
108