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/*
* KDF defined in NIST SP 800-56c
* (C) 2016 Kai Michaelis
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/sp800_108.h>
#include <botan/sp800_56c.h>
#include <botan/hmac.h>
namespace Botan {
SP800_56C* SP800_56C::make(const Spec& spec)
{
if(auto exp = SP800_108_Feedback::make(spec))
{
if(auto mac = MessageAuthenticationCode::create(spec.arg(0)))
return new SP800_56C(mac.release(), exp);
if(auto mac = MessageAuthenticationCode::create("HMAC(" + spec.arg(0) + ")"))
return new SP800_56C(mac.release(), exp);
}
return nullptr;
}
size_t SP800_56C::kdf(byte key[], size_t key_len,
const byte secret[], size_t secret_len,
const byte salt[], size_t salt_len) const
{
// Randomness Extraction
secure_vector< byte > k_dk, context;
m_prf->set_key(salt, salt_len);
m_prf->update(secret, secret_len);
m_prf->final(k_dk);
// Key Expansion
m_exp->kdf(key, key_len, k_dk.data(), k_dk.size(), context.data(), context.size());
return key_len;
}
}
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