1// Copyright (c) 2014-present The Bitcoin Core developers
2// Distributed under the MIT software license, see the accompanying
3// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5#include <crypto/hmac_sha256.h>
6
7#include <crypto/sha256.h>
8#include <support/cleanse.h>
9
10#include <cstring>
11
12CHMAC_SHA256::CHMAC_SHA256(const unsigned char* key, size_t keylen)
13{
14    unsigned char rkey[64];
15    if (keylen <= 64) {
16        memcpy(rkey, key, keylen);
17        memset(rkey + keylen, 0, 64 - keylen);
18    } else {
19        CSHA256().Write(key, keylen).Finalize(rkey);
20        memset(rkey + 32, 0, 32);
21    }
22
23    for (int n = 0; n < 64; n++)
24        rkey[n] ^= 0x5c;
25    outer.Write(rkey, 64);
26
27    for (int n = 0; n < 64; n++)
28        rkey[n] ^= 0x5c ^ 0x36;
29    inner.Write(rkey, 64);
30
31    memory_cleanse(rkey, sizeof(rkey));
32}
33
34void CHMAC_SHA256::Finalize(unsigned char hash[OUTPUT_SIZE])
35{
36    unsigned char temp[32];
37    inner.Finalize(temp);
38    outer.Write(temp, 32).Finalize(hash);
39    memory_cleanse(temp, sizeof(temp));
40}
41