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/*
* PBKDF2
* (C) 1999-2007 Jack Lloyd
* (C) 2018 Ribose Inc
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#include <botan/pbkdf2.h>
#include <botan/exceptn.h>
#include <botan/internal/rounding.h>
#include <botan/internal/timer.h>
namespace Botan {
namespace {
void pbkdf2_set_key(MessageAuthenticationCode& prf,
const char* password,
size_t password_len)
{
try
{
prf.set_key(cast_char_ptr_to_uint8(password), password_len);
}
catch(Invalid_Key_Length&)
{
throw Exception("PBKDF2 cannot accept passphrase of the given size");
}
}
}
size_t
pbkdf2(MessageAuthenticationCode& prf,
uint8_t out[],
size_t out_len,
const std::string& password,
const uint8_t salt[], size_t salt_len,
size_t iterations,
std::chrono::milliseconds msec)
{
if(iterations == 0)
{
iterations = PBKDF2(prf, out_len, msec).iterations();
}
PBKDF2 pbkdf2(prf, iterations);
pbkdf2.derive_key(out, out_len,
password.c_str(), password.size(),
salt, salt_len);
return iterations;
}
namespace {
size_t tune_pbkdf2(MessageAuthenticationCode& prf,
size_t output_length,
uint32_t msec)
{
const size_t prf_sz = prf.output_length();
BOTAN_ASSERT_NOMSG(prf_sz > 0);
secure_vector<uint8_t> U(prf_sz);
const size_t trial_iterations = 10000;
// Short output ensures we only need a single PBKDF2 block
Timer timer("PBKDF2");
const std::chrono::milliseconds tune_msec(30);
prf.set_key(nullptr, 0);
timer.run_until_elapsed(tune_msec, [&]() {
uint8_t out[16] = { 0 };
uint8_t salt[16] = { 0 };
pbkdf2(prf, out, sizeof(out), salt, sizeof(salt), trial_iterations);
});
if(timer.events() == 0)
return trial_iterations;
const uint64_t duration_nsec = timer.value() / timer.events();
const uint64_t desired_nsec = static_cast<uint64_t>(msec) * 1000000;
if(duration_nsec > desired_nsec)
return trial_iterations;
const size_t blocks_needed = (output_length + prf_sz - 1) / prf_sz;
const size_t multiplier = (desired_nsec / duration_nsec / blocks_needed);
if(multiplier == 0)
return trial_iterations;
else
return trial_iterations * multiplier;
}
}
void pbkdf2(MessageAuthenticationCode& prf,
uint8_t out[],
size_t out_len,
const uint8_t salt[],
size_t salt_len,
size_t iterations)
{
clear_mem(out, out_len);
if(out_len == 0)
return;
const size_t prf_sz = prf.output_length();
BOTAN_ASSERT_NOMSG(prf_sz > 0);
secure_vector<uint8_t> U(prf_sz);
uint32_t counter = 1;
while(out_len)
{
const size_t prf_output = std::min<size_t>(prf_sz, out_len);
prf.update(salt, salt_len);
prf.update_be(counter++);
prf.final(U.data());
xor_buf(out, U.data(), prf_output);
for(size_t i = 1; i != iterations; ++i)
{
prf.update(U);
prf.final(U.data());
xor_buf(out, U.data(), prf_output);
}
out_len -= prf_output;
out += prf_output;
}
}
// PBKDF interface
size_t
PKCS5_PBKDF2::pbkdf(uint8_t key[], size_t key_len,
const std::string& password,
const uint8_t salt[], size_t salt_len,
size_t iterations,
std::chrono::milliseconds msec) const
{
if(iterations == 0)
{
iterations = PBKDF2(*m_mac, key_len, msec).iterations();
}
PBKDF2 pbkdf2(*m_mac, iterations);
pbkdf2.derive_key(key, key_len,
password.c_str(), password.size(),
salt, salt_len);
return iterations;
}
std::string PKCS5_PBKDF2::name() const
{
return "PBKDF2(" + m_mac->name() + ")";
}
PBKDF* PKCS5_PBKDF2::clone() const
{
return new PKCS5_PBKDF2(m_mac->clone());
}
// PasswordHash interface
PBKDF2::PBKDF2(const MessageAuthenticationCode& prf, size_t olen, std::chrono::milliseconds msec) :
m_prf(prf.clone()),
m_iterations(tune_pbkdf2(*m_prf, olen, msec.count()))
{}
std::string PBKDF2::to_string() const
{
return "PBKDF2(" + m_prf->name() + "," + std::to_string(m_iterations) + ")";
}
void PBKDF2::derive_key(uint8_t out[], size_t out_len,
const char* password, const size_t password_len,
const uint8_t salt[], size_t salt_len) const
{
pbkdf2_set_key(*m_prf, password, password_len);
pbkdf2(*m_prf, out, out_len, salt, salt_len, m_iterations);
}
std::string PBKDF2_Family::name() const
{
return "PBKDF2(" + m_prf->name() + ")";
}
std::unique_ptr<PasswordHash> PBKDF2_Family::tune(size_t output_len, std::chrono::milliseconds msec, size_t) const
{
return std::unique_ptr<PasswordHash>(new PBKDF2(*m_prf, output_len, msec));
}
std::unique_ptr<PasswordHash> PBKDF2_Family::default_params() const
{
return std::unique_ptr<PasswordHash>(new PBKDF2(*m_prf, 150000));
}
std::unique_ptr<PasswordHash> PBKDF2_Family::from_params(size_t iter, size_t, size_t) const
{
return std::unique_ptr<PasswordHash>(new PBKDF2(*m_prf, iter));
}
std::unique_ptr<PasswordHash> PBKDF2_Family::from_iterations(size_t iter) const
{
return std::unique_ptr<PasswordHash>(new PBKDF2(*m_prf, iter));
}
}
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