/////////////////////////////////////////////////////////////////// // Copyright Christopher Kormanyos 2023. // // Distributed under the Boost Software License, // // Version 1.0. (See accompanying file LICENSE_1_0.txt // // or copy at http://www.boost.org/LICENSE_1_0.txt) // /////////////////////////////////////////////////////////////////// // This work uses (significantly) translated and modified parts // of andreacorbellini/ecc // see also: https://github.com/andreacorbellini/ecc // and also: https://github.com/andreacorbellini/ecc/blob/master/scripts/ecdsa.py // Full original andreacorbellini/ecc copyright information follows. /*---------------------------------------------------------------------------- The MIT License (MIT) Copyright (c) 2015 Andrea Corbellini 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. -----------------------------------------------------------------------------*/ // For algorithm description of ECDSA, please consult also: // D. Hankerson, A. Menezes, S. Vanstone, "Guide to Elliptic // Curve Cryptography", Springer 2004, Chapter 4, in particular // Algorithm 4.24 (keygen on page 180), and Algorithms 4.29 and 4.30. // Complete descriptions of sign/verify are featured on page 184. // For another algorithm description of ECDSA, // see also: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5.pdf // For algorithm description of SHA-2 HASH-256, // see also: https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf // The SHA-2 HASH-256 implementation has been taken (with slight modification) // from: https://github.com/imahjoub/hash_sha256 #include #include #include #include #include #include #include #include

namespace example013_ecdsa
{
  #if defined(WIDE_INTEGER_NAMESPACE)
  using WIDE_INTEGER_NAMESPACE::math::wide_integer::detail::fill_unsafe;
  #else
  using ::math::wide_integer::detail::fill_unsafe;
  #endif

  class hash_sha256
  {
  public:
    #if defined(WIDE_INTEGER_NAMESPACE)
    using result_type = WIDE_INTEGER_NAMESPACE::math::wide_integer::detail::array_detail::array (UINT8_C(32))>;
    #else
    using result_type = ::math::wide_integer::detail::array_detail::array (UINT8_C(32))>;
    #endif

    // LCOV_EXCL_START
    constexpr hash_sha256()                       = default;
    constexpr hash_sha256(const hash_sha256&)     = default;
    constexpr hash_sha256(hash_sha256&&) noexcept = default;
    ~hash_sha256() = default;

    constexpr auto operator=(hash_sha256&&) noexcept -> hash_sha256& = default;
    constexpr auto operator=(const hash_sha256&) ->     hash_sha256& = default;
    // LCOV_EXCL_STOP

    constexpr auto hash(const std::uint8_t* msg, const size_t length) -> result_type
    {
      init();
      update(msg, length);
      return finalize();
    }

    constexpr void init()
    {
      my_datalen = static_cast (UINT8_C(0));
      my_bitlen  = static_cast (UINT8_C(0));

      transform_context[static_cast (UINT8_C(0))] = static_cast (UINT32_C(0x6A09E667));
      transform_context[static_cast (UINT8_C(1))] = static_cast (UINT32_C(0xBB67AE85));
      transform_context[static_cast (UINT8_C(2))] = static_cast (UINT32_C(0x3C6EF372));
      transform_context[static_cast (UINT8_C(3))] = static_cast (UINT32_C(0xA54FF53A));
      transform_context[static_cast (UINT8_C(4))] = static_cast (UINT32_C(0x510E527F));
      transform_context[static_cast (UINT8_C(5))] = static_cast (UINT32_C(0x9B05688C));
      transform_context[static_cast (UINT8_C(6))] = static_cast (UINT32_C(0x1F83D9AB));
      transform_context[static_cast (UINT8_C(7))] = static_cast (UINT32_C(0x5BE0CD19));
    }

    constexpr void update(const std::uint8_t* msg, const size_t length)
    {
      for (auto i = static_cast (UINT8_C(0)); i < length; ++i)
      {
        my_data[my_datalen] = msg[i]; // NOLINT(cppcoreguidelines-pro-bounds-pointer-arithmetic,cppcoreguidelines-pro-bounds-constant-array-index)
        my_datalen++;

        if(my_datalen == static_cast (UINT8_C(64)))
        {
          // LCOV_EXCL_START
          sha256_transform();

          my_datalen = static_cast (UINT8_C(0));

          my_bitlen = static_cast (my_bitlen + static_cast (UINT16_C(512)));
          // LCOV_EXCL_STOP
        }
      }
    }

    constexpr auto finalize() -> result_type
    {
      result_type hash_result { };

      auto hash_index = static_cast (my_datalen);

      my_data[hash_index] = static_cast (UINT8_C(0x80)); // NOLINT(cppcoreguidelines-pro-bounds-pointer-arithmetic,cppcoreguidelines-pro-bounds-constant-array-index)

      ++hash_index;

      // Pad whatever data is left in the buffer.
      if(my_datalen < static_cast (UINT8_C(56U)))
      {
        fill_unsafe((my_data.begin() + hash_index), (my_data.begin() + static_cast (UINT8_C(56))), static_cast (UINT8_C(0)));
      }
      else
      {
        // LCOV_EXCL_START
        fill_unsafe((my_data.begin() + hash_index), my_data.end(), static_cast (UINT8_C(0)));

        sha256_transform();

        fill_unsafe(my_data.begin(), my_data.begin() + static_cast (UINT8_C(56)), static_cast (UINT8_C(0)));
        // LCOV_EXCL_STOP
      }

      // Append to the padding the total message length (in bits) and subsequently transform.
      my_bitlen =
        static_cast (
            my_bitlen
          + static_cast (
              static_cast (my_datalen) * static_cast (UINT8_C(8))
            )
        );

      my_data[static_cast (UINT8_C(63))] = static_cast (my_bitlen >> static_cast (UINT8_C( 0)));
      my_data[static_cast (UINT8_C(62))] = static_cast (my_bitlen >> static_cast (UINT8_C( 8)));
      my_data[static_cast (UINT8_C(61))] = static_cast (my_bitlen >> static_cast (UINT8_C(16)));
      my_data[static_cast (UINT8_C(60))] = static_cast (my_bitlen >> static_cast (UINT8_C(24)));
      my_data[static_cast (UINT8_C(59))] = static_cast