hmac_sha256.cpp

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// Copyright (c) 2014-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <crypto/hmac_sha256.h>
 
#include <crypto/sha256.h>
#include <support/cleanse.h>
 
#include <cstring>
 
CHMAC_SHA256::CHMAC_SHA256(const unsigned char* key, size_t keylen)
{
    unsigned char rkey[64];
    if (keylen <= 64) {
        memcpy(rkey, key, keylen);
        memset(rkey + keylen, 0, 64 - keylen);
    } else {
        CSHA256().Write(key, keylen).Finalize(rkey);
        memset(rkey + 32, 0, 32);
    }
 
    for (int n = 0; n < 64; n++)
        rkey[n] ^= 0x5c;
    outer.Write(rkey, 64);
 
    for (int n = 0; n < 64; n++)
        rkey[n] ^= 0x5c ^ 0x36;
    inner.Write(rkey, 64);
 
    memory_cleanse(rkey, sizeof(rkey));
}
 
void CHMAC_SHA256::Finalize(unsigned char hash[OUTPUT_SIZE])
{
    unsigned char temp[32];
    inner.Finalize(temp);
    outer.Write(temp, 32).Finalize(hash);
    memory_cleanse(temp, sizeof(temp));
}