strobe.hpp

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#ifndef KAGOME_STROBE_HPP
#define KAGOME_STROBE_HPP

#include <array>
#include <cstdint>
#include <cstring>
#include <gsl/span>
#include <tuple>
#include <type_traits>

#include <boost/assert.hpp>

#include "crypto/keccak/keccak.h"
#include "primitives/math.hpp"

namespace kagome::primitives {

  class Strobe final {
    static constexpr size_t kBufferSize = 200ull;
    static constexpr size_t kAlignment = 8ull;
    static constexpr uint8_t kStrobeR = 166;

    using Flags = uint8_t;
    using Position = uint8_t;

    static constexpr Flags kFlag_NU = 0x00;  // NU = No Use
    static constexpr Flags kFlag_I = 0x01;
    static constexpr Flags kFlag_A = 0x02;
    static constexpr Flags kFlag_C = 0x04;
    static constexpr Flags kFlag_T = 0x08;
    static constexpr Flags kFlag_M = 0x10;
    static constexpr Flags kFlag_K = 0x20;

    uint8_t raw_data[kBufferSize + kAlignment - 1ull + 3ull];
    uint8_t *const buffer_;
    Position &current_position_;
    Position &begin_position_;
    Flags &current_state_;

    template <typename T, size_t kOffset = 0ull>
    constexpr T *as() {
      static_assert(kOffset < count<T>(), "Overflow!");
      return (reinterpret_cast<T *>(buffer_) + kOffset);  // NOLINT
    }

    template <typename T, size_t kOffset = 0ull>
    constexpr const T *as() const {
      static_assert(kOffset < count<T>(), "Overflow!");
      return (reinterpret_cast<const T *>(buffer_) + kOffset);  // NOLINT
    }

    template <typename T>
    T *as(Position offset) {
      BOOST_ASSERT(static_cast<size_t>(offset) < count<T>());
      return (as<T>() + offset);
    }

    template <typename T>
    static constexpr size_t count() {
      static_assert(!std::is_reference_v<T>, "Can not be a reference type.");
      static_assert(!std::is_pointer_v<T>, "Can not be a pointer.");
      static_assert(std::is_integral_v<T>, "Cast to non integral type.");
      return kBufferSize / sizeof(T);
    }

    template <size_t kOffset, typename T, size_t N>
    void load(const T (&data)[N]) {  // NOLINT
      static_assert(kOffset + N <= count<T>(), "Load overflows!");
      std::memcpy(as<T, kOffset>(), data, N);
    }

    template <typename T, size_t N>
    void absorb(const T (&src)[N]) {
      for (const auto i : src) {
        *as<uint8_t>(current_position_++) ^= static_cast<uint8_t>(i);
        if (kStrobeR == current_position_) {
          runF();
        }
      }
    }

    template <typename T, size_t N>
    void overwrite(const T (&src)[N]) {
      for (const auto i : src) {
        *as<uint8_t>(current_position_++) = static_cast<uint8_t>(i);
        if (kStrobeR == current_position_) {
          runF();
        }
      }
    }

    template <typename T, size_t N>
    void squeeze(T (&src)[N]) {
      for (auto &i : src) {
        i = static_cast<T>(*as<uint8_t>(current_position_));
        *as<uint8_t>(current_position_++) = 0;
        if (kStrobeR == current_position_) {
          runF();
        }
      }
    }

    template <bool kMore, Flags kFlags>
    void beginOp() {
      static_assert((kFlags & kFlag_T) == 0, "T flag doesn't support");
      if constexpr (kMore) {
        BOOST_ASSERT(current_state_ == kFlags);
        return;
      }

      const auto old_begin = begin_position_;
      begin_position_ = current_position_ + 1;
      current_state_ = kFlags;
      absorb({old_begin, kFlags});

      if constexpr (0 != (kFlags & (kFlag_C | kFlag_K))) {
        if (current_position_ != 0) {
          runF();
        }
      }
    }

    void runF() {
      *as<uint8_t>(current_position_) ^= begin_position_;
      *as<uint8_t>(current_position_ + 1) ^= 0x04;
      *as<uint8_t>(kStrobeR + 1) ^= 0x80;
      keccakf(as<uint64_t>());

      current_position_ = 0;
      begin_position_ = 0;
    }

   public:
    Strobe()
        : buffer_{reinterpret_cast<uint8_t *>(
            math::roundUp<kAlignment>(reinterpret_cast<uintptr_t>(raw_data)))},
          current_position_{*(buffer_ + kBufferSize)},
          begin_position_{*(buffer_ + kBufferSize + 1ull)},
          current_state_{*(buffer_ + kBufferSize + 2ull)} {}

    Strobe(const Strobe &other) : Strobe() {
      std::copy(std::begin(other.raw_data),
                std::end(other.raw_data),
                std::begin(raw_data));
    };

    Strobe &operator=(const Strobe &other) {
      std::copy(std::begin(other.raw_data),
                std::end(other.raw_data),
                std::begin(raw_data));
      return *this;
    }

    Strobe(Strobe &&) = delete;
    Strobe &operator=(Strobe &&) = delete;

    template <typename T, size_t N>
    void initialize(const T (&label)[N]) {
      constexpr bool kUseRuntimeCalculation = false;

      if constexpr (kUseRuntimeCalculation) {
        std::memset(as<uint8_t>(), 0, count<uint8_t>());
        load<0ull>((uint8_t[6]){1, kStrobeR + 2, 1, 0, 1, 96});
        load<6ull>("STROBEv1.0.2");
        keccakf(as<uint64_t>());
      } else {
        load<0ull>((uint8_t[kBufferSize]){
            0x9c, 0x6d, 0x16, 0x8f, 0xf8, 0xfd, 0x55, 0xda, 0x2a, 0xa7, 0x3c,
            0x23, 0x55, 0x65, 0x35, 0x63, 0xdc, 0xc,  0x47, 0x5c, 0x55, 0x15,
            0x26, 0xf6, 0x73, 0x3b, 0xea, 0x22, 0xf1, 0x6c, 0xb5, 0x7c, 0xd3,
            0x1f, 0x68, 0x2e, 0x66, 0xe,  0xe9, 0x12, 0x82, 0x4a, 0x77, 0x22,
            0x1,  0xee, 0x13, 0x94, 0x22, 0x6f, 0x4a, 0xfc, 0xb6, 0x2d, 0x33,
            0x12, 0x93, 0xcc, 0x92, 0xe8, 0xa6, 0x24, 0xac, 0xf6, 0xe1, 0xb6,
            0x0,  0x95, 0xe3, 0x22, 0xbb, 0xfb, 0xc8, 0x45, 0xe5, 0xb2, 0x69,
            0x95, 0xfe, 0x7d, 0x7c, 0x84, 0x13, 0x74, 0xd1, 0xff, 0x58, 0x98,
            0xc9, 0x2e, 0xe0, 0x63, 0x6b, 0x6,  0x72, 0x73, 0x21, 0xc9, 0x2a,
            0x60, 0x39, 0x7,  0x3,  0x53, 0x49, 0xcc, 0xbb, 0x1b, 0x92, 0xb7,
            0xb0, 0x5,  0x7e, 0x8f, 0xa8, 0x7f, 0xce, 0xbc, 0x7e, 0x88, 0x65,
            0x6f, 0xcb, 0x45, 0xae, 0x4,  0xbc, 0x34, 0xca, 0xbe, 0xae, 0xbe,
            0x79, 0xd9, 0x17, 0x50, 0xc0, 0xe8, 0xbf, 0x13, 0xb9, 0x66, 0x50,
            0x4d, 0x13, 0x43, 0x59, 0x72, 0x65, 0xdd, 0x88, 0x65, 0xad, 0xf9,
            0x14, 0x9,  0xcc, 0x9b, 0x20, 0xd5, 0xf4, 0x74, 0x44, 0x4,  0x1f,
            0x97, 0xb6, 0x99, 0xdd, 0xfb, 0xde, 0xe9, 0x1e, 0xa8, 0x7b, 0xd0,
            0x9b, 0xf8, 0xb0, 0x2d, 0xa7, 0x5a, 0x96, 0xe9, 0x47, 0xf0, 0x7f,
            0x5b, 0x65, 0xbb, 0x4e, 0x6e, 0xfe, 0xfa, 0xa1, 0x6a, 0xbf, 0xd9,
            0xfb, 0xf6});
      }

      current_position_ = 0;
      current_state_ = kFlag_NU;
      begin_position_ = 0;

      metaAd<false>(label);
    }

    template <bool kMore, typename T, size_t N>
    void ad(const T (&src)[N]) {
      beginOp<kMore, kFlag_A>();
      absorb(src);
    }

    template <bool kMore, typename T, size_t N>
    void metaAd(const T (&label)[N]) {
      beginOp<kMore, kFlag_M | kFlag_A>();
      absorb(label);
    }

    template <bool kMore, typename T, size_t N>
    void prf(T (&data)[N]) {
      beginOp<kMore, kFlag_I | kFlag_A | kFlag_C>();
      squeeze(data);
    }

    template <bool kMore, typename T, size_t N>
    void key(const T (&data)[N]) {
      beginOp<kMore, kFlag_A | kFlag_C>();
      overwrite(data);
    }

    auto data() {
      return gsl::make_span(as<const uint8_t>(), count<uint8_t>() + 3ull);
    }

    auto data() const {
      return gsl::make_span(as<const uint8_t>(), count<uint8_t>() + 3ull);
    }
  };

}  // namespace kagome::primitives

#endif  // KAGOME_STROBE_HPP