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/*
* OpenPGP S2K
* (C) 1999-2007,2017 Jack Lloyd
* (C) 2018 Ribose Inc
*
* Distributed under the terms of the Botan license
*/
#include <botan/pgp_s2k.h>
#include <botan/exceptn.h>
#include <botan/internal/timer.h>
namespace Botan {
uint8_t RFC4880_encode_count(size_t desired_iterations)
{
/*
Only 256 different iterations are actually representable in OpenPGP format ...
*/
for(size_t c = 0; c < 256; ++c)
{
// TODO could binary search
const size_t decoded_iter = RFC4880_decode_count(static_cast<uint8_t>(c));
if(decoded_iter >= desired_iterations)
return static_cast<uint8_t>(c);
}
return 255;
}
size_t RFC4880_decode_count(uint8_t iter)
{
/*
PGP stores the iteration count as a single byte
Thus it can only actually take on one of 256 values, based on the
formula in RFC 4880 section 3.6.1.3
*/
static const uint32_t OPENPGP_S2K_ITERS[256] = {
1024, 1088, 1152, 1216, 1280, 1344, 1408, 1472, 1536, 1600,
1664, 1728, 1792, 1856, 1920, 1984, 2048, 2176, 2304, 2432,
2560, 2688, 2816, 2944, 3072, 3200, 3328, 3456, 3584, 3712,
3840, 3968, 4096, 4352, 4608, 4864, 5120, 5376, 5632, 5888,
6144, 6400, 6656, 6912, 7168, 7424, 7680, 7936, 8192, 8704,
9216, 9728, 10240, 10752, 11264, 11776, 12288, 12800, 13312,
13824, 14336, 14848, 15360, 15872, 16384, 17408, 18432, 19456,
20480, 21504, 22528, 23552, 24576, 25600, 26624, 27648, 28672,
29696, 30720, 31744, 32768, 34816, 36864, 38912, 40960, 43008,
45056, 47104, 49152, 51200, 53248, 55296, 57344, 59392, 61440,
63488, 65536, 69632, 73728, 77824, 81920, 86016, 90112, 94208,
98304, 102400, 106496, 110592, 114688, 118784, 122880, 126976,
131072, 139264, 147456, 155648, 163840, 172032, 180224, 188416,
196608, 204800, 212992, 221184, 229376, 237568, 245760, 253952,
262144, 278528, 294912, 311296, 327680, 344064, 360448, 376832,
393216, 409600, 425984, 442368, 458752, 475136, 491520, 507904,
524288, 557056, 589824, 622592, 655360, 688128, 720896, 753664,
786432, 819200, 851968, 884736, 917504, 950272, 983040, 1015808,
1048576, 1114112, 1179648, 1245184, 1310720, 1376256, 1441792,
1507328, 1572864, 1638400, 1703936, 1769472, 1835008, 1900544,
1966080, 2031616, 2097152, 2228224, 2359296, 2490368, 2621440,
2752512, 2883584, 3014656, 3145728, 3276800, 3407872, 3538944,
3670016, 3801088, 3932160, 4063232, 4194304, 4456448, 4718592,
4980736, 5242880, 5505024, 5767168, 6029312, 6291456, 6553600,
6815744, 7077888, 7340032, 7602176, 7864320, 8126464, 8388608,
8912896, 9437184, 9961472, 10485760, 11010048, 11534336,
12058624, 12582912, 13107200, 13631488, 14155776, 14680064,
15204352, 15728640, 16252928, 16777216, 17825792, 18874368,
19922944, 20971520, 22020096, 23068672, 24117248, 25165824,
26214400, 27262976, 28311552, 29360128, 30408704, 31457280,
32505856, 33554432, 35651584, 37748736, 39845888, 41943040,
44040192, 46137344, 48234496, 50331648, 52428800, 54525952,
56623104, 58720256, 60817408, 62914560, 65011712 };
return OPENPGP_S2K_ITERS[iter];
}
namespace {
void pgp_s2k(HashFunction& hash,
uint8_t output_buf[], size_t output_len,
const char* password, const size_t password_size,
const uint8_t salt[], size_t salt_len,
size_t iterations)
{
if(iterations > 1 && salt_len == 0)
throw Invalid_Argument("OpenPGP S2K requires a salt in iterated mode");
secure_vector<uint8_t> input_buf(salt_len + password_size);
if(salt_len > 0)
{
copy_mem(&input_buf[0], salt, salt_len);
}
if(password_size > 0)
{
copy_mem(&input_buf[salt_len],
cast_char_ptr_to_uint8(password),
password_size);
}
secure_vector<uint8_t> hash_buf(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);
hash.update(zero_padding);
// The input is always fully processed even if iterations is very small
if(input_buf.empty() == false)
{
size_t left = std::max(iterations, input_buf.size());
while(left > 0)
{
const size_t input_to_take = std::min(left, input_buf.size());
hash.update(input_buf.data(), input_to_take);
left -= input_to_take;
}
}
hash.final(hash_buf.data());
copy_mem(output_buf + generated, hash_buf.data(), output_this_pass);
generated += output_this_pass;
++pass;
}
}
}
size_t OpenPGP_S2K::pbkdf(uint8_t output_buf[], size_t output_len,
const std::string& password,
const uint8_t salt[], size_t salt_len,
size_t iterations,
std::chrono::milliseconds msec) const
{
std::unique_ptr<PasswordHash> pwdhash;
if(iterations == 0)
{
RFC4880_S2K_Family s2k_params(m_hash->clone());
iterations = s2k_params.tune(output_len, msec, 0)->iterations();
}
pgp_s2k(*m_hash, output_buf, output_len,
password.c_str(), password.size(),
salt, salt_len,
iterations);
return iterations;
}
std::string RFC4880_S2K_Family::name() const
{
return "OpenPGP-S2K(" + m_hash->name() + ")";
}
std::unique_ptr<PasswordHash> RFC4880_S2K_Family::tune(size_t output_len, std::chrono::milliseconds msec, size_t) const
{
const std::chrono::milliseconds tune_time = std::chrono::milliseconds(30);
const size_t buf_size = 1024;
Botan::secure_vector<uint8_t> buffer(buf_size);
Timer timer("RFC4880_S2K", buf_size);
timer.run_until_elapsed(tune_time, [&]() {
m_hash->update(buffer);
});
// bug in Timer::bytes_per_second?
const double hash_bytes_per_second = buf_size * timer.bytes_per_second();
const uint64_t desired_nsec = msec.count() * 1000000;
const size_t hash_size = m_hash->output_length();
const size_t blocks_required = (output_len <= hash_size ? 1 : (output_len + hash_size - 1) / hash_size);
const double bytes_to_be_hashed = (hash_bytes_per_second * (desired_nsec / 1000000000.0)) / blocks_required;
const size_t iterations = RFC4880_round_iterations(static_cast<size_t>(bytes_to_be_hashed));
return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iterations));
}
std::unique_ptr<PasswordHash> RFC4880_S2K_Family::from_params(size_t iter, size_t, size_t) const
{
return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iter));
}
std::unique_ptr<PasswordHash> RFC4880_S2K_Family::default_params() const
{
return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), 50331648));
}
std::unique_ptr<PasswordHash> RFC4880_S2K_Family::from_iterations(size_t iter) const
{
return std::unique_ptr<PasswordHash>(new RFC4880_S2K(m_hash->clone(), iter));
}
RFC4880_S2K::RFC4880_S2K(HashFunction* hash, size_t iterations) :
m_hash(hash),
m_iterations(iterations)
{
}
std::string RFC4880_S2K::to_string() const
{
return "OpenPGP-S2K(" + m_hash->name() + "," + std::to_string(m_iterations) + ")";
}
void RFC4880_S2K::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
{
pgp_s2k(*m_hash, out, out_len,
password, password_len,
salt, salt_len,
m_iterations);
}
}
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