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/*
* HMAC
* (C) 1999-2007,2014 Jack Lloyd
* 2007 Yves Jerschow
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/internal/mac_utils.h>
#include <botan/hmac.h>
namespace Botan {
HMAC* HMAC::make(const Spec& spec)
{
if(spec.arg_count() == 1)
{
if(HashFunction* h = get_hash_function(spec.arg(0)))
return new HMAC(h);
}
return nullptr;
}
/*
* Update a HMAC Calculation
*/
void HMAC::add_data(const byte input[], size_t length)
{
m_hash->update(input, length);
}
/*
* Finalize a HMAC Calculation
*/
void HMAC::final_result(byte mac[])
{
m_hash->final(mac);
m_hash->update(m_okey);
m_hash->update(mac, output_length());
m_hash->final(mac);
m_hash->update(m_ikey);
}
/*
* HMAC Key Schedule
*/
void HMAC::key_schedule(const byte key[], size_t length)
{
m_hash->clear();
m_ikey.resize(m_hash->hash_block_size());
m_okey.resize(m_hash->hash_block_size());
std::fill(m_ikey.begin(), m_ikey.end(), 0x36);
std::fill(m_okey.begin(), m_okey.end(), 0x5C);
if(length > m_hash->hash_block_size())
{
secure_vector<byte> hmac_key = m_hash->process(key, length);
xor_buf(m_ikey, hmac_key, hmac_key.size());
xor_buf(m_okey, hmac_key, hmac_key.size());
}
else
{
xor_buf(m_ikey, key, length);
xor_buf(m_okey, key, length);
}
m_hash->update(m_ikey);
}
/*
* Clear memory of sensitive data
*/
void HMAC::clear()
{
m_hash->clear();
zap(m_ikey);
zap(m_okey);
}
/*
* Return the name of this type
*/
std::string HMAC::name() const
{
return "HMAC(" + m_hash->name() + ")";
}
/*
* Return a clone of this object
*/
MessageAuthenticationCode* HMAC::clone() const
{
return new HMAC(m_hash->clone());
}
/*
* HMAC Constructor
*/
HMAC::HMAC(HashFunction* hash) : m_hash(hash)
{
if(m_hash->hash_block_size() == 0)
throw Invalid_Argument("HMAC cannot be used with " + m_hash->name());
}
}
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