text: # Copyright 2018 Donald Stufft and individual contributors
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  # http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  
  from nacl import exceptions as exc
  from nacl._sodium import ffi, lib
  from nacl.exceptions import ensure
  
  
  has_crypto_core_ed25519 = bool(lib.PYNACL_HAS_CRYPTO_CORE_ED25519)
  
  crypto_core_ed25519_BYTES = 0
  crypto_core_ed25519_SCALARBYTES = 0
  crypto_core_ed25519_NONREDUCEDSCALARBYTES = 0
  
  if has_crypto_core_ed25519:
      crypto_core_ed25519_BYTES = lib.crypto_core_ed25519_bytes()
      crypto_core_ed25519_SCALARBYTES = lib.crypto_core_ed25519_scalarbytes()
      crypto_core_ed25519_NONREDUCEDSCALARBYTES = (
          lib.crypto_core_ed25519_nonreducedscalarbytes()
      )
  
  
  def crypto_core_ed25519_is_valid_point(p: bytes) -> bool:
      """
      Check if ``p`` represents a point on the edwards25519 curve, in canonical
      form, on the main subgroup, and that the point doesn't have a small order.
  
      :param p: a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
                representing a point on the edwards25519 curve
      :type p: bytes
      :return: point validity
      :rtype: bool
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes) and len(p) == crypto_core_ed25519_BYTES,
          "Point must be a crypto_core_ed25519_BYTES long bytes sequence",
          raising=exc.TypeError,
      )
  
      rc = lib.crypto_core_ed25519_is_valid_point(p)
      return rc == 1
  
  
  def crypto_core_ed25519_add(p: bytes, q: bytes) -> bytes:
      """
      Add two points on the edwards25519 curve.
  
      :param p: a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
                representing a point on the edwards25519 curve
      :type p: bytes
      :param q: a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
                representing a point on the edwards25519 curve
      :type q: bytes
      :return: a point on the edwards25519 curve represented as
               a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes)
          and isinstance(q, bytes)
          and len(p) == crypto_core_ed25519_BYTES
          and len(q) == crypto_core_ed25519_BYTES,
          "Each point must be a {} long bytes sequence".format(
              "crypto_core_ed25519_BYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_BYTES)
  
      rc = lib.crypto_core_ed25519_add(r, p, q)
      ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
  
      return ffi.buffer(r, crypto_core_ed25519_BYTES)[:]
  
  
  def crypto_core_ed25519_sub(p: bytes, q: bytes) -> bytes:
      """
      Subtract a point from another on the edwards25519 curve.
  
      :param p: a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
                representing a point on the edwards25519 curve
      :type p: bytes
      :param q: a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
                representing a point on the edwards25519 curve
      :type q: bytes
      :return: a point on the edwards25519 curve represented as
               a :py:data:`.crypto_core_ed25519_BYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes)
          and isinstance(q, bytes)
          and len(p) == crypto_core_ed25519_BYTES
          and len(q) == crypto_core_ed25519_BYTES,
          "Each point must be a {} long bytes sequence".format(
              "crypto_core_ed25519_BYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_BYTES)
  
      rc = lib.crypto_core_ed25519_sub(r, p, q)
      ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
  
      return ffi.buffer(r, crypto_core_ed25519_BYTES)[:]
  
  
  def crypto_core_ed25519_scalar_invert(s: bytes) -> bytes:
      """
      Return the multiplicative inverse of integer ``s`` modulo ``L``,
      i.e an integer ``i`` such that ``s * i = 1 (mod L)``, where ``L``
      is the order of the main subgroup.
  
      Raises a ``exc.RuntimeError`` if ``s`` is the integer zero.
  
      :param s: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type s: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(s, bytes) and len(s) == crypto_core_ed25519_SCALARBYTES,
          "Integer s must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      rc = lib.crypto_core_ed25519_scalar_invert(r, s)
      ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_negate(s: bytes) -> bytes:
      """
      Return the integer ``n`` such that ``s + n = 0 (mod L)``, where ``L``
      is the order of the main subgroup.
  
      :param s: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type s: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(s, bytes) and len(s) == crypto_core_ed25519_SCALARBYTES,
          "Integer s must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_negate(r, s)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_complement(s: bytes) -> bytes:
      """
      Return the complement of integer ``s`` modulo ``L``, i.e. an integer
      ``c`` such that ``s + c = 1 (mod L)``, where ``L`` is the order of
      the main subgroup.
  
      :param s: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type s: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(s, bytes) and len(s) == crypto_core_ed25519_SCALARBYTES,
          "Integer s must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_complement(r, s)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_add(p: bytes, q: bytes) -> bytes:
      """
      Add integers ``p`` and ``q`` modulo ``L``, where ``L`` is the order of
      the main subgroup.
  
      :param p: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type p: bytes
      :param q: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type q: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes)
          and isinstance(q, bytes)
          and len(p) == crypto_core_ed25519_SCALARBYTES
          and len(q) == crypto_core_ed25519_SCALARBYTES,
          "Each integer must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_add(r, p, q)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_sub(p: bytes, q: bytes) -> bytes:
      """
      Subtract integers ``p`` and ``q`` modulo ``L``, where ``L`` is the
      order of the main subgroup.
  
      :param p: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type p: bytes
      :param q: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type q: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes)
          and isinstance(q, bytes)
          and len(p) == crypto_core_ed25519_SCALARBYTES
          and len(q) == crypto_core_ed25519_SCALARBYTES,
          "Each integer must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_sub(r, p, q)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_mul(p: bytes, q: bytes) -> bytes:
      """
      Multiply integers ``p`` and ``q`` modulo ``L``, where ``L`` is the
      order of the main subgroup.
  
      :param p: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type p: bytes
      :param q: a :py:data:`.crypto_core_ed25519_SCALARBYTES`
                long bytes sequence representing an integer
      :type q: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(p, bytes)
          and isinstance(q, bytes)
          and len(p) == crypto_core_ed25519_SCALARBYTES
          and len(q) == crypto_core_ed25519_SCALARBYTES,
          "Each integer must be a {} long bytes sequence".format(
              "crypto_core_ed25519_SCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_mul(r, p, q)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  
  
  def crypto_core_ed25519_scalar_reduce(s: bytes) -> bytes:
      """
      Reduce integer ``s`` to ``s`` modulo ``L``, where ``L`` is the order
      of the main subgroup.
  
      :param s: a :py:data:`.crypto_core_ed25519_NONREDUCEDSCALARBYTES`
                long bytes sequence representing an integer
      :type s: bytes
      :return: an integer represented as a
                :py:data:`.crypto_core_ed25519_SCALARBYTES` long bytes sequence
      :rtype: bytes
      :raises nacl.exceptions.UnavailableError: If called when using a
          minimal build of libsodium.
      """
      ensure(
          has_crypto_core_ed25519,
          "Not available in minimal build",
          raising=exc.UnavailableError,
      )
  
      ensure(
          isinstance(s, bytes)
          and len(s) == crypto_core_ed25519_NONREDUCEDSCALARBYTES,
          "Integer s must be a {} long bytes sequence".format(
              "crypto_core_ed25519_NONREDUCEDSCALARBYTES"
          ),
          raising=exc.TypeError,
      )
  
      r = ffi.new("unsigned char[]", crypto_core_ed25519_SCALARBYTES)
  
      lib.crypto_core_ed25519_scalar_reduce(r, s)
  
      return ffi.buffer(r, crypto_core_ed25519_SCALARBYTES)[:]
  