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/*
* X448 Internal
* (C) 2024 Jack Lloyd
* 2024 Fabian Albert - Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
#ifndef BOTAN_X448_INTERNAL_H_
#define BOTAN_X448_INTERNAL_H_
#include <botan/secmem.h>
#include <botan/strong_type.h>
namespace Botan {
constexpr size_t X448_LEN = 56;
using Point448 = Strong<std::array<uint8_t, X448_LEN>, struct Point448_>;
// Note that we do not use the scalar of x448_scalar.h since the x448 algorithm
// requires a scalar that is even. When reducing (modulo the group order) the scalar using
// this class, the computation becomes invalid. Since we do not need to reduce, we
// simply work on bytes for x448 */
using ScalarX448 = Strong<std::array<uint8_t, X448_LEN>, struct ScalarX448_>;
/**
* @brief Multiply a scalar with the standard group element (5)
*
* @param k scalar
* @return encoded point
*/
Point448 x448_basepoint(const ScalarX448& k);
/**
* @brief Multiply a scalar @p k with a point @p u
*
* @param k scalar
* @param u point on curve
* @return k * u
*/
Point448 x448(const ScalarX448& k, const Point448& u);
/// Encode a point to a 56 byte vector. RFC 7748 Section 5 (encodeUCoordinate)
secure_vector<uint8_t> encode_point(const Point448& p);
/// Decode a point from a byte array. RFC 7748 Section 5 (decodeUCoordinate)
Point448 decode_point(std::span<const uint8_t> p_bytes);
/// Decode a scalar from a byte array. RFC 7748 Section 5 (decodeScalar448)
ScalarX448 decode_scalar(std::span<const uint8_t> scalar_bytes);
} // namespace Botan
#endif // BOTAN_X448_INTERNAL_H_