pbkdf2.hpp

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//---------------------------------------------------------------------------//
// Copyright (c) 2018-2020 Mikhail Komarov <nemo@nil.foundation>
//
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//---------------------------------------------------------------------------//
 
#ifndef CRYPTO3_PBKDF_PBKDF2_HPP
#define CRYPTO3_PBKDF_PBKDF2_HPP
 
#include <nil/crypto3/pbkdf/detail/pbkdf2/pbkdf2_functions.hpp>
 
#include <chrono>
 
namespace nil {
    namespace crypto3 {
        namespace pbkdf {
            template<typename MessageAuthenticationCode>
            class pbkdf2 {
                typedef detail::pbkdf2_functions<MessageAuthenticationCode> policy_type;
 
            public:
                typedef typename policy_type::mac_type mac_type;
 
                constexpr static const std::size_t digest_bits = policy_type::digest_bits;
                typedef typename policy_type::digest_type digest_type;
 
                constexpr static const std::size_t salt_bits = policy_type::salt_bits;
                typedef typename policy_type::salt_type salt_type;
 
                size_t derive(digest_type &digest, const std::string &passphrase, const salt_type &salt,
                              size_t iterations, std::chrono::milliseconds msec) {
                    clear_mem(out, out_len);
 
                    if (out_len == 0) {
                        return 0;
                    }
 
                    try {
                        prf.set_key(cast_char_ptr_to_uint8(passphrase.data()), passphrase.size());
                    } catch (Invalid_Key_Length &) {
                        throw Exception("PBKDF2 with " + prf.name() + " cannot accept passphrases of length " +
                                        std::to_string(passphrase.size()));
                    }
 
                    const size_t prf_sz = prf.output_length();
                    secure_vector<uint8_t> U(prf_sz);
 
                    const std::size_t blocks_needed = policy_type::round_up(out_len, prf_sz) / prf_sz;
 
                    std::chrono::microseconds usec_per_block =
                        std::chrono::duration_cast<std::chrono::microseconds>(msec) / blocks_needed;
 
                    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);
 
                        if (iterations == 0) {
                            /*
                            If no iterations set, run the first block to calibrate based
                            on how long hashing takes on whatever machine we're running on.
                            */
 
                            const auto start = std::chrono::high_resolution_clock::now();
 
                            iterations = 1;    // the first iteration we did above
 
                            while (true) {
                                prf.update(U);
                                prf.final(U.data());
                                xor_buf(out, U.data(), prf_output);
                                iterations++;
 
                                /*
                                Only break on relatively 'even' iterations. For one it
                                avoids confusion, and likely some broken implementations
                                break on getting completely randomly distributed values
                                */
                                if (iterations % 10000 == 0) {
                                    auto time_taken = std::chrono::high_resolution_clock::now() - start;
                                    auto usec_taken = std::chrono::duration_cast<std::chrono::microseconds>(time_taken);
                                    if (usec_taken > usec_per_block) {
                                        break;
                                    }
                                }
                            }
                        } else {
                            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;
                    }
 
                    return iterations;
                }
            };
        }    // namespace pbkdf
    }        // namespace crypto3
}    // namespace nil
 
#endif