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/*
* HKDF
* (C) 2013 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/hkdf.h>
namespace Botan {
std::string HKDF::name() const
{
return "HKDF(" + m_prf->name() + ")";
}
void HKDF::clear()
{
m_extractor->clear();
m_prf->clear();
}
void HKDF::start_extract(const byte salt[], size_t salt_len)
{
m_extractor->set_key(salt, salt_len);
}
void HKDF::extract(const byte input[], size_t input_len)
{
m_extractor->update(input, input_len);
}
void HKDF::finish_extract()
{
m_prf->set_key(m_extractor->final());
}
void HKDF::expand(byte output[], size_t output_len,
const byte info[], size_t info_len)
{
if(output_len > m_prf->output_length() * 255)
throw std::invalid_argument("HKDF requested output too large");
byte counter = 1;
secure_vector<byte> T;
while(output_len)
{
m_prf->update(T);
m_prf->update(info, info_len);
m_prf->update(counter++);
T = m_prf->final();
const size_t to_write = std::min(T.size(), output_len);
copy_mem(&output[0], &T[0], to_write);
output += to_write;
output_len -= to_write;
}
}
}
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