5 hashfunc_t hfunc, int hlen, int hblock,
7 unsigned char *in, int n,
8 unsigned char *key, int k
11 unsigned char hashbuf[32];
12 unsigned char k_xor_ipad[128];
13 unsigned char k_xor_opad[128];
14 unsigned char catbuf[256];
17 if(sizeof(hashbuf) < (size_t) hlen)
18 Host_Error("Invalid hash function used for HMAC - too long hash length");
19 if(sizeof(k_xor_ipad) < (size_t) hblock)
20 Host_Error("Invalid hash function used for HMAC - too long hash block length");
21 if(sizeof(catbuf) < (size_t) hblock + (size_t) hlen)
22 Host_Error("Invalid hash function used for HMAC - too long hash block length");
23 if(sizeof(catbuf) < (size_t) hblock + (size_t) n)
24 Host_Error("Invalid hash function used for HMAC - too long message length");
28 // hash the key if it is too long
29 // NO! that makes it too short if hblock != hlen
30 // just shorten it, then
31 // hfunc(hashbuf, key, k);
37 // zero pad the key if it is too short
38 memcpy(k_xor_opad, key, k);
39 for(i = k; i < hblock; ++i)
45 for(i = 0; i < hblock; ++i)
47 k_xor_ipad[i] = key[i] ^ 0x36;
48 k_xor_opad[i] = key[i] ^ 0x5c;
51 memcpy(catbuf, k_xor_ipad, hblock);
52 memcpy(catbuf + hblock, in, n);
53 hfunc(hashbuf, catbuf, hblock + n);
54 memcpy(catbuf, k_xor_opad, hblock);
55 memcpy(catbuf + hblock, hashbuf, hlen);
56 hfunc(out, catbuf, hblock + hlen);