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/*
* KDFs defined in NIST SP 800-108
* (C) 2016 Kai Michaelis
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/sp800_108.h>
#include <botan/hmac.h>
namespace Botan {
SP800_108_Counter* SP800_108_Counter::make(const Spec& spec)
{
if(auto mac = MessageAuthenticationCode::create(spec.arg(0)))
return new SP800_108_Counter(mac.release());
if(auto mac = MessageAuthenticationCode::create("HMAC(" + spec.arg(0) + ")"))
return new SP800_108_Counter(mac.release());
return nullptr;
}
size_t SP800_108_Counter::kdf(byte key[], size_t key_len,
const byte secret[], size_t secret_len,
const byte salt[], size_t salt_len) const
{
const std::size_t prf_len = m_prf->output_length();
byte *p = key;
uint32_t counter = 1;
secure_vector<byte> tmp;
m_prf->set_key(secret, secret_len);
while(p < key + key_len && counter != 0)
{
const std::size_t to_copy = std::min< std::size_t >(key + key_len - p, prf_len);
byte be_cnt[4] = { 0 };
store_be(counter, be_cnt);
m_prf->update(be_cnt,4);
m_prf->update(salt, salt_len);
m_prf->final(tmp);
std::move(tmp.begin(), tmp.begin() + to_copy, p);
++counter;
if (counter == 0)
throw Invalid_Argument("Can't process more than 4GB");
p += to_copy;
}
return key_len;
}
SP800_108_Feedback* SP800_108_Feedback::make(const Spec& spec)
{
if(auto mac = MessageAuthenticationCode::create(spec.arg(0)))
return new SP800_108_Feedback(mac.release());
if(auto mac = MessageAuthenticationCode::create("HMAC(" + spec.arg(0) + ")"))
return new SP800_108_Feedback(mac.release());
return nullptr;
}
size_t SP800_108_Feedback::kdf(byte key[], size_t key_len,
const byte secret[], size_t secret_len,
const byte salt[], size_t salt_len) const
{
const std::size_t prf_len = m_prf->output_length();
const std::size_t iv_len = (salt_len >= prf_len ? prf_len : 0);
byte *p = key;
uint32_t counter = 1;
secure_vector< byte > prev(salt, salt + iv_len);
secure_vector< byte > ctx(salt + iv_len, salt + salt_len);
m_prf->set_key(secret, secret_len);
while(p < key + key_len && counter != 0)
{
const std::size_t to_copy = std::min< std::size_t >(key + key_len - p, prf_len);
byte be_cnt[4] = { 0 };
store_be(counter, be_cnt);
m_prf->update(prev);
m_prf->update(be_cnt,4);
m_prf->update(ctx);
m_prf->final(prev);
std::copy(prev.begin(), prev.begin() + to_copy, p);
++counter;
if (counter == 0)
throw Invalid_Argument("Can't process more than 4GB");
p += to_copy;
}
return key_len;
}
SP800_108_Pipeline* SP800_108_Pipeline::make(const Spec& spec)
{
if(auto mac = MessageAuthenticationCode::create(spec.arg(0)))
return new SP800_108_Pipeline(mac.release());
if(auto mac = MessageAuthenticationCode::create("HMAC(" + spec.arg(0) + ")"))
return new SP800_108_Pipeline(mac.release());
return nullptr;
}
size_t SP800_108_Pipeline::kdf(byte key[], size_t key_len,
const byte secret[], size_t secret_len,
const byte salt[], size_t salt_len) const
{
const std::size_t prf_len = m_prf->output_length();
byte *p = key;
uint32_t counter = 1;
secure_vector<byte> ai(salt, salt + salt_len), ki;
m_prf->set_key(secret,secret_len);
while(p < key + key_len && counter != 0)
{
// A(i)
m_prf->update(ai);
m_prf->final(ai);
// K(i)
const std::size_t to_copy = std::min< std::size_t >(key + key_len - p, prf_len);
byte be_cnt[4] = { 0 };
store_be(counter, be_cnt);
m_prf->update(ai);
m_prf->update(be_cnt,4);
m_prf->update(salt, salt_len);
m_prf->final(ki);
std::copy(ki.begin(), ki.begin() + to_copy, p);
++counter;
if (counter == 0)
throw Invalid_Argument("Can't process more than 4GB");
p += to_copy;
}
return key_len;
}
}
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