|
3
|
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 /* Submited by Dobes Vandermeer ([email protected]) */ |
|
|
12 |
|
|
13 #include "mycrypt.h" |
|
|
14 |
|
|
15 /* |
|
|
16 (1) append zeros to the end of K to create a B byte string |
|
|
17 (e.g., if K is of length 20 bytes and B=64, then K will be |
|
|
18 appended with 44 zero bytes 0x00) |
|
|
19 (2) XOR (bitwise exclusive-OR) the B byte string computed in step |
|
|
20 (1) with ipad (ipad = the byte 0x36 repeated B times) |
|
|
21 (3) append the stream of data 'text' to the B byte string resulting |
|
|
22 from step (2) |
|
|
23 (4) apply H to the stream generated in step (3) |
|
|
24 (5) XOR (bitwise exclusive-OR) the B byte string computed in |
|
|
25 step (1) with opad (opad = the byte 0x5C repeated B times.) |
|
|
26 (6) append the H result from step (4) to the B byte string |
|
|
27 resulting from step (5) |
|
|
28 (7) apply H to the stream generated in step (6) and output |
|
|
29 the result |
|
|
30 */ |
|
|
31 |
|
|
32 #ifdef HMAC |
|
|
33 |
|
|
34 #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize |
|
|
35 |
|
|
36 int hmac_init(hmac_state *hmac, int hash, const unsigned char *key, unsigned long keylen) |
|
|
37 { |
|
|
38 unsigned char buf[MAXBLOCKSIZE]; |
|
|
39 unsigned long hashsize; |
|
|
40 unsigned long i, z; |
|
|
41 int err; |
|
|
42 |
|
|
43 _ARGCHK(hmac != NULL); |
|
|
44 _ARGCHK(key != NULL); |
|
|
45 |
|
|
46 if ((err = hash_is_valid(hash)) != CRYPT_OK) { |
|
|
47 return err; |
|
|
48 } |
|
|
49 |
|
|
50 /* valid key length? */ |
|
|
51 if (keylen == 0) { |
|
|
52 return CRYPT_INVALID_KEYSIZE; |
|
|
53 } |
|
|
54 |
|
|
55 hmac->hash = hash; |
|
|
56 |
|
|
57 // (1) make sure we have a large enough key |
|
|
58 hashsize = hash_descriptor[hash].hashsize; |
|
|
59 if(keylen > HMAC_BLOCKSIZE) { |
|
|
60 z = (unsigned long)sizeof(hmac->key); |
|
|
61 if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) { |
|
|
62 return err; |
|
|
63 } |
|
|
64 if(hashsize < HMAC_BLOCKSIZE) { |
|
|
65 zeromem((hmac->key) + hashsize, (size_t)(HMAC_BLOCKSIZE - hashsize)); |
|
|
66 } |
|
|
67 keylen = hashsize; |
|
|
68 } else { |
|
|
69 memcpy(hmac->key, key, (size_t)keylen); |
|
|
70 if(keylen < HMAC_BLOCKSIZE) { |
|
|
71 zeromem((hmac->key) + keylen, (size_t)(HMAC_BLOCKSIZE - keylen)); |
|
|
72 } |
|
|
73 } |
|
|
74 |
|
|
75 // Create the initial vector for step (3) |
|
|
76 for(i=0; i < HMAC_BLOCKSIZE; i++) { |
|
|
77 buf[i] = hmac->key[i] ^ 0x36; |
|
|
78 } |
|
|
79 |
|
|
80 // Pre-pend that to the hash data |
|
|
81 hash_descriptor[hash].init(&hmac->md); |
|
|
82 hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE); |
|
|
83 |
|
|
84 return CRYPT_OK; |
|
|
85 } |
|
|
86 |
|
|
87 #endif |
