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/*
* OpenPGP S2K
* (C) 1999-2007,2017 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
#include <botan/pgp_s2k.h>
namespace Botan {
//static
uint8_t OpenPGP_S2K::encode_count(size_t desired_iterations)
{
/*
Only 256 different iterations are actually representable in OpenPGP format ...
*/
for(size_t c = 0; c < 256; ++c)
{
size_t decoded_iter = OpenPGP_S2K::decode_count(c);
if(decoded_iter >= desired_iterations)
return c;
}
}
//static
size_t OpenPGP_S2K::decode_count(uint8_t iter)
{
// See RFC 4880 section 3.7.1.3
return (16 + (iter & 0x0F)) << ((iter >> 4) + 6);
}
size_t OpenPGP_S2K::pbkdf(uint8_t output_buf[], size_t output_len,
const std::string& passphrase,
const uint8_t salt[], size_t salt_len,
size_t iterations,
std::chrono::milliseconds msec) const
{
if(iterations == 0 && msec.count() > 0) // FIXME
throw Not_Implemented("OpenPGP_S2K does not implemented timed KDF");
secure_vector<uint8_t> input_buf(salt_len + passphrase.size());
if(salt_len > 0)
{
copy_mem(&input_buf[0], salt, salt_len);
}
if(passphrase.empty() == false)
{
copy_mem(&input_buf[salt_len],
reinterpret_cast<const uint8_t*>(passphrase.data()),
passphrase.size());
}
/*
The input is always fully processed even if iterations is very small
*/
const size_t to_hash = std::max(iterations, input_buf.size());
secure_vector<uint8_t> hash_buf(m_hash->output_length());
size_t pass = 0;
size_t generated = 0;
while(generated != output_len)
{
const size_t output_this_pass =
std::min(hash_buf.size(), output_len - generated);
// Preload some number of zero bytes (empty first iteration)
std::vector<uint8_t> zero_padding(pass);
m_hash->update(zero_padding);
size_t left = to_hash;
while(left > 0)
{
const size_t input_to_take = std::min(left, input_buf.size());
m_hash->update(input_buf.data(), input_to_take);
left -= input_to_take;
}
m_hash->final(hash_buf.data());
copy_mem(output_buf + generated, hash_buf.data(), output_this_pass);
generated += output_this_pass;
++pass;
}
return iterations;
}
}
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