merkle_damgard_construction.hpp

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//---------------------------------------------------------------------------//
// Copyright (c) 2018-2020 Mikhail Komarov <nemo@nil.foundation>
// Copyright (c) 2020 Alexander Sokolov <asokolov@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
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//---------------------------------------------------------------------------//
 
#ifndef CRYPTO3_HASH_MERKLE_DAMGARD_CONSTRUCTION_HPP
#define CRYPTO3_HASH_MERKLE_DAMGARD_CONSTRUCTION_HPP
 
#include <nil/crypto3/hash/detail/nop_finalizer.hpp>
 
#include <nil/crypto3/detail/static_digest.hpp>
#include <nil/crypto3/detail/pack.hpp>
 
namespace nil {
    namespace crypto3 {
        namespace hashes {
            template<typename Params, typename IV, typename Compressor, typename Padding,
                     typename Finalizer = detail::nop_finalizer>
            class merkle_damgard_construction {
            public:
                typedef IV iv_generator;
                typedef Compressor compressor_functor;
                typedef Padding padding_functor;
                typedef Finalizer finalizer_functor;
 
                typedef typename Params::digest_endian endian_type;
 
                constexpr static const std::size_t word_bits = compressor_functor::word_bits;
                typedef typename compressor_functor::word_type word_type;
 
                constexpr static const std::size_t state_bits = compressor_functor::state_bits;
                constexpr static const std::size_t state_words = compressor_functor::state_words;
                typedef typename compressor_functor::state_type state_type;
 
                constexpr static const std::size_t block_bits = compressor_functor::block_bits;
                constexpr static const std::size_t block_words = compressor_functor::block_words;
                typedef typename compressor_functor::block_type block_type;
 
                constexpr static const std::size_t digest_bits = Params::digest_bits;
                constexpr static const std::size_t digest_bytes = digest_bits / octet_bits;
                constexpr static const std::size_t digest_words = digest_bits / word_bits;
                typedef static_digest<digest_bits> digest_type;
 
            protected:
                constexpr static const std::size_t length_bits = Params::length_bits;
                // FIXME: do something more intelligent than capping at 64
                constexpr static const std::size_t length_type_bits = length_bits < word_bits ? word_bits :
                                                                      length_bits > 64        ? 64 :
                                                                                                length_bits;
                typedef typename boost::uint_t<length_type_bits>::least length_type;
                constexpr static const std::size_t length_words = length_bits / word_bits;
                BOOST_STATIC_ASSERT(!length_bits || length_bits % word_bits == 0);
 
            public:
                template<typename Integer = std::size_t>
                inline merkle_damgard_construction &process_block(const block_type &block, Integer seen = Integer()) {
                    compressor_functor::process_block(state_, block);
                    return *this;
                }
 
                inline digest_type digest(const block_type &block = block_type(),
                                          length_type total_seen = length_type()) {
                    using namespace nil::crypto3::detail;
 
                    block_type b = block;
                    std::size_t block_seen = total_seen % block_bits;
                    // Process block if block is full
                    if (total_seen && !block_seen)
                        process_block(b);
 
                    // Pad last message block
                    padding_functor padding;
                    padding(b, block_seen);
 
                    // Process block if total length cannot be appended
                    if (block_seen + length_bits > block_bits) {
                        process_block(b);
                        std::fill(b.begin(), b.end(), 0);
                    }
 
                    // Append total length to the last block
                    append_length<int>(b, total_seen);
 
                    // Process the last block
                    process_block(b);
 
                    // Apply finalizer
                    finalizer_functor()(state_);
 
                    // Convert digest to byte representation
                    digest_type d;
                    pack_from<endian_type, word_bits, octet_bits>(state_.begin(), state_.begin() + digest_words,
                                                                  d.begin());
                    return d;
                }
 
                merkle_damgard_construction() {
                    reset();
                }
 
                inline void reset(const state_type &s) {
                    state_ = s;
                }
 
                inline void reset() {
                    iv_generator iv;
                    reset(iv());
                }
 
                inline const state_type &state() const {
                    return state_;
                }
 
            protected:
                template<typename Dummy>
                typename std::enable_if<length_bits && sizeof(Dummy)>::type append_length(block_type &block,
                                                                                          length_type length) {
                    using namespace nil::crypto3::detail;
 
                    std::array<length_type, 1> length_array = {{length}};
                    std::array<word_type, length_words> length_words_array;
                    pack<endian_type, endian_type, length_bits, word_bits>(length_array.begin(), length_array.end(),
                                                                           length_words_array.begin());
                    // Append length
                    for (std::size_t i = length_words; i; --i)
                        block[block_words - i] = length_words_array[length_words - i];
                }
 
                template<typename Dummy>
                typename std::enable_if<!(length_bits && sizeof(Dummy))>::type append_length(block_type &block,
                                                                                             length_type length) {
                    // No appending requested, so nothing to do
                }
                state_type state_;
            };
 
        }    // namespace hashes
    }        // namespace crypto3
}    // namespace nil
 
#endif    // CRYPTO3_HASH_MERKLE_DAMGARD_BLOCK_HASH_HPP