Modified source engine (2017) developed by valve and leaked in 2020. Not for commercial purporses
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// hmac.cpp - written and placed in the public domain by Wei Dai
#include "pch.h"
#ifndef CRYPTOPP_IMPORTS
#include "hmac.h"
NAMESPACE_BEGIN(CryptoPP)
void HMAC_Base::UncheckedSetKey(const byte *userKey, unsigned int keylength, const NameValuePairs &)
{
AssertValidKeyLength(keylength);
Restart();
HashTransformation &hash = AccessHash();
unsigned int blockSize = hash.BlockSize();
if (!blockSize)
throw InvalidArgument("HMAC: can only be used with a block-based hash function");
m_buf.resize(2*AccessHash().BlockSize() + AccessHash().DigestSize());
if (keylength <= blockSize)
memcpy(AccessIpad(), userKey, keylength);
else
{
AccessHash().CalculateDigest(AccessIpad(), userKey, keylength);
keylength = hash.DigestSize();
}
assert(keylength <= blockSize);
memset(AccessIpad()+keylength, 0, blockSize-keylength);
for (unsigned int i=0; i<blockSize; i++)
{
AccessOpad()[i] = AccessIpad()[i] ^ 0x5c;
AccessIpad()[i] ^= 0x36;
}
}
void HMAC_Base::KeyInnerHash()
{
assert(!m_innerHashKeyed);
HashTransformation &hash = AccessHash();
hash.Update(AccessIpad(), hash.BlockSize());
m_innerHashKeyed = true;
}
void HMAC_Base::Restart()
{
if (m_innerHashKeyed)
{
AccessHash().Restart();
m_innerHashKeyed = false;
}
}
void HMAC_Base::Update(const byte *input, size_t length)
{
if (!m_innerHashKeyed)
KeyInnerHash();
AccessHash().Update(input, length);
}
void HMAC_Base::TruncatedFinal(byte *mac, size_t size)
{
ThrowIfInvalidTruncatedSize(size);
HashTransformation &hash = AccessHash();
if (!m_innerHashKeyed)
KeyInnerHash();
hash.Final(AccessInnerHash());
hash.Update(AccessOpad(), hash.BlockSize());
hash.Update(AccessInnerHash(), hash.DigestSize());
hash.TruncatedFinal(mac, size);
m_innerHashKeyed = false;
}
NAMESPACE_END
#endif