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# Copyright 2013-2018 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_scalarmult_ed25519 = bool(lib.PYNACL_HAS_CRYPTO_SCALARMULT_ED25519)
crypto_scalarmult_BYTES: int = lib.crypto_scalarmult_bytes()
crypto_scalarmult_SCALARBYTES: int = lib.crypto_scalarmult_scalarbytes()
crypto_scalarmult_ed25519_BYTES = 0
crypto_scalarmult_ed25519_SCALARBYTES = 0
if has_crypto_scalarmult_ed25519:
crypto_scalarmult_ed25519_BYTES = lib.crypto_scalarmult_ed25519_bytes()
crypto_scalarmult_ed25519_SCALARBYTES = (
lib.crypto_scalarmult_ed25519_scalarbytes()
)
def crypto_scalarmult_base(n: bytes) -> bytes:
"""
Computes and returns the scalar product of a standard group element and an
integer ``n``.
:param n: bytes
:rtype: bytes
"""
q = ffi.new("unsigned char[]", crypto_scalarmult_BYTES)
rc = lib.crypto_scalarmult_base(q, n)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_SCALARBYTES)[:]
def crypto_scalarmult(n: bytes, p: bytes) -> bytes:
"""
Computes and returns the scalar product of the given group element and an
integer ``n``.
:param p: bytes
:param n: bytes
:rtype: bytes
"""
q = ffi.new("unsigned char[]", crypto_scalarmult_BYTES)
rc = lib.crypto_scalarmult(q, n, p)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_SCALARBYTES)[:]
def crypto_scalarmult_ed25519_base(n: bytes) -> bytes:
"""
Computes and returns the scalar product of a standard group element and an
integer ``n`` on the edwards25519 curve.
:param n: a :py:data:`.crypto_scalarmult_ed25519_SCALARBYTES` long bytes
sequence representing a scalar
:type n: bytes
:return: a point on the edwards25519 curve, represented as a
:py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
:rtype: bytes
:raises nacl.exceptions.UnavailableError: If called when using a
minimal build of libsodium.
"""
ensure(
has_crypto_scalarmult_ed25519,
"Not available in minimal build",
raising=exc.UnavailableError,
)
ensure(
isinstance(n, bytes)
and len(n) == crypto_scalarmult_ed25519_SCALARBYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_SCALARBYTES"
),
raising=exc.TypeError,
)
q = ffi.new("unsigned char[]", crypto_scalarmult_ed25519_BYTES)
rc = lib.crypto_scalarmult_ed25519_base(q, n)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_ed25519_BYTES)[:]
def crypto_scalarmult_ed25519_base_noclamp(n: bytes) -> bytes:
"""
Computes and returns the scalar product of a standard group element and an
integer ``n`` on the edwards25519 curve. The integer ``n`` is not clamped.
:param n: a :py:data:`.crypto_scalarmult_ed25519_SCALARBYTES` long bytes
sequence representing a scalar
:type n: bytes
:return: a point on the edwards25519 curve, represented as a
:py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
:rtype: bytes
:raises nacl.exceptions.UnavailableError: If called when using a
minimal build of libsodium.
"""
ensure(
has_crypto_scalarmult_ed25519,
"Not available in minimal build",
raising=exc.UnavailableError,
)
ensure(
isinstance(n, bytes)
and len(n) == crypto_scalarmult_ed25519_SCALARBYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_SCALARBYTES"
),
raising=exc.TypeError,
)
q = ffi.new("unsigned char[]", crypto_scalarmult_ed25519_BYTES)
rc = lib.crypto_scalarmult_ed25519_base_noclamp(q, n)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_ed25519_BYTES)[:]
def crypto_scalarmult_ed25519(n: bytes, p: bytes) -> bytes:
"""
Computes and returns the scalar product of a *clamped* integer ``n``
and the given group element on the edwards25519 curve.
The scalar is clamped, as done in the public key generation case,
by setting to zero the bits in position [0, 1, 2, 255] and setting
to one the bit in position 254.
:param n: a :py:data:`.crypto_scalarmult_ed25519_SCALARBYTES` long bytes
sequence representing a scalar
:type n: bytes
:param p: a :py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
representing a point on the edwards25519 curve
:type p: bytes
:return: a point on the edwards25519 curve, represented as a
:py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
:rtype: bytes
:raises nacl.exceptions.UnavailableError: If called when using a
minimal build of libsodium.
"""
ensure(
has_crypto_scalarmult_ed25519,
"Not available in minimal build",
raising=exc.UnavailableError,
)
ensure(
isinstance(n, bytes)
and len(n) == crypto_scalarmult_ed25519_SCALARBYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_SCALARBYTES"
),
raising=exc.TypeError,
)
ensure(
isinstance(p, bytes) and len(p) == crypto_scalarmult_ed25519_BYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_BYTES"
),
raising=exc.TypeError,
)
q = ffi.new("unsigned char[]", crypto_scalarmult_ed25519_BYTES)
rc = lib.crypto_scalarmult_ed25519(q, n, p)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_ed25519_BYTES)[:]
def crypto_scalarmult_ed25519_noclamp(n: bytes, p: bytes) -> bytes:
"""
Computes and returns the scalar product of an integer ``n``
and the given group element on the edwards25519 curve. The integer
``n`` is not clamped.
:param n: a :py:data:`.crypto_scalarmult_ed25519_SCALARBYTES` long bytes
sequence representing a scalar
:type n: bytes
:param p: a :py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
representing a point on the edwards25519 curve
:type p: bytes
:return: a point on the edwards25519 curve, represented as a
:py:data:`.crypto_scalarmult_ed25519_BYTES` long bytes sequence
:rtype: bytes
:raises nacl.exceptions.UnavailableError: If called when using a
minimal build of libsodium.
"""
ensure(
has_crypto_scalarmult_ed25519,
"Not available in minimal build",
raising=exc.UnavailableError,
)
ensure(
isinstance(n, bytes)
and len(n) == crypto_scalarmult_ed25519_SCALARBYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_SCALARBYTES"
),
raising=exc.TypeError,
)
ensure(
isinstance(p, bytes) and len(p) == crypto_scalarmult_ed25519_BYTES,
"Input must be a {} long bytes sequence".format(
"crypto_scalarmult_ed25519_BYTES"
),
raising=exc.TypeError,
)
q = ffi.new("unsigned char[]", crypto_scalarmult_ed25519_BYTES)
rc = lib.crypto_scalarmult_ed25519_noclamp(q, n, p)
ensure(rc == 0, "Unexpected library error", raising=exc.RuntimeError)
return ffi.buffer(q, crypto_scalarmult_ed25519_BYTES)[:]
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