eme_pkcs.hpp

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//---------------------------------------------------------------------------//
// Copyright (c) 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
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//---------------------------------------------------------------------------//
 
#ifndef CRYPTO3_EME_PKCS1_HPP
#define CRYPTO3_EME_PKCS1_HPP
 
#include <nil/crypto3/pkpad/eme.hpp>
 
namespace nil {
    namespace crypto3 {
        namespace pubkey {
            namespace padding {
                template<typename Scheme, typename Hash>
                class eme_pkcs1v15 : public eme<Scheme, Hash> {
                public:
                    template<typename UniformRandomBitGenerator, typename RandomNumberDistribution,
                             typename InputIterator, typename OutputIterator>
                    OutputIterator pad(InputIterator first, InputIterator last, OutputIterator out,
                                       std::size_t key_length, UniformRandomBitGenerator rand,
                                       RandomNumberDistribution dist) {
                        std::ptrdiff_t distance = std::distance(first, last);
 
                        if (distance > maximum_input_size(key_length)) {
                            throw std::invalid_argument("PKCS1: Input is too large");
                        }
 
                        key_length /= 8;
 
                        secure_vector<uint8_t> out(key_length);
 
                        out[0] = 0x02;
                        rand.randomize(out.data() + 1, (key_length - distance - 2));
 
                        for (size_t j = 1; j != key_length - distance - 1; ++j) {
                            if (out[j] == 0) {
                                out[j] = rand.next_nonzero_byte();
                            }
                        }
 
                        buffer_insert(out, key_length - distance, in, distance);
 
                        return out;
                    }
 
                    template<typename InputIterator, typename OutputIterator>
                    OutputIterator unpad(InputIterator first, InputIterator last, OutputIterator out) {
                        std::ptrdiff_t distance = std::distance(first, last);
 
                        if (distance < 2) {
                            throw std::invalid_argument("");
                        }
 
                        ct::poison(in, distance);
 
                        uint8_t bad_input_m = 0;
                        uint8_t seen_zero_m = 0;
                        size_t delim_idx = 0;
 
                        bad_input_m |= ~ct::is_equal<uint8_t>(*first, 0);
                        bad_input_m |= ~ct::is_equal<uint8_t>(*(first + 1), 2);
 
                        for (size_t i = 2; i < distance; ++i) {
                            const uint8_t is_zero_m = ct::is_zero<uint8_t>(in[i]);
 
                            delim_idx += ct::select<uint8_t>(~seen_zero_m, 1, 0);
 
                            bad_input_m |= is_zero_m & ct::expand_mask<uint8_t>(i < 10);
                            seen_zero_m |= is_zero_m;
                        }
 
                        bad_input_m |= ~seen_zero_m;
                        bad_input_m |= ct::is_less<size_t>(delim_idx, 8);
 
                        ct::unpoison(in, distance);
                        ct::unpoison(bad_input_m);
                        ct::unpoison(delim_idx);
 
                        secure_vector<uint8_t> output(&in[delim_idx + 2], &in[distance]);
                        ct::cond_zero_mem(bad_input_m, output.data(), output.size());
 
                        return out;
                    }
 
                    virtual size_t maximum_input_size(std::size_t key_bits) const override {
                        if (key_bits / 8 > 10) {
                            return ((key_bits / 8) - 10);
                        } else {
                            return 0;
                        }
                    }
                };
            }    // namespace padding
        }        // namespace pubkey
    }            // namespace crypto3
}    // namespace nil
 
#endif