def from_affine(cls, coords, curve: ec.EllipticCurve = None):
"""
Returns a Point object from the given affine coordinates in a tuple in
the format of (x, y) and a given curve.
"""
curve = curve if curve is not None else default_curve()
try:
curve_nid = backend._elliptic_curve_to_nid(curve)
except AttributeError:
# Presume that the user passed in the curve_nid
curve_nid = curve
affine_x, affine_y = coords
if type(affine_x) == int:
affine_x = openssl._int_to_bn(affine_x)
if type(affine_y) == int:
affine_y = openssl._int_to_bn(affine_y)
group = openssl._get_ec_group_by_curve_nid(curve_nid)
ec_point = openssl._get_EC_POINT_via_affine(affine_x,
affine_y,
ec_group=group)
return cls(ec_point, curve_nid, group)
def from_int(cls, num: int, curve: Optional[Curve] = None) -> 'CurveBN':
"""
Returns a CurveBN object from a given integer on a curve.
By default, the underlying OpenSSL BIGNUM has BN_FLG_CONSTTIME set for
constant time operations.
"""
curve = curve if curve is not None else default_curve()
conv_bn = openssl._int_to_bn(num, curve)
return cls(conv_bn, curve)
def from_affine(cls,
coords: Tuple[int, int],
curve: Optional[Curve] = None) -> 'Point':
"""
Returns a Point object from the given affine coordinates in a tuple in
the format of (x, y) and a given curve.
"""
curve = curve if curve is not None else default_curve()
affine_x, affine_y = coords
if type(affine_x) == int:
affine_x = openssl._int_to_bn(affine_x, curve=curve)
if type(affine_y) == int:
affine_y = openssl._int_to_bn(affine_y, curve=curve)
ec_point = openssl._get_EC_POINT_via_affine(affine_x, affine_y, curve)
return cls(ec_point, curve)
def __eq__(self, other):
"""
Compares the two BIGNUMS or int.
"""
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, None, None, None)
# -1 less than, 0 is equal to, 1 is greater than
return not bool(backend._lib.BN_cmp(self.bignum, other.bignum))
def __eq__(self, other) -> bool:
"""
Compares the two BIGNUMS or int.
"""
# TODO: Should this stay in or not?
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, self.curve)
# -1 less than, 0 is equal to, 1 is greater than
return not bool(backend._lib.BN_cmp(self.bignum, other.bignum))
def __mod__(self, other):
"""
Performs a BN_nnmod on two BIGNUMS.
"""
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, None, None, None)
rem = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.BN_nnmod(rem, self.bignum, other.bignum, bn_ctx)
backend.openssl_assert(res == 1)
return CurveBN(rem, self.curve_nid, self.group, self.order)
def __sub__(self, other: Union[int, 'CurveBN']) -> 'CurveBN':
"""
Performs a BN_mod_sub on two BIGNUMS.
"""
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, self.curve)
diff = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.BN_mod_sub(diff, self.bignum, other.bignum,
self.curve.order, bn_ctx)
backend.openssl_assert(res == 1)
return CurveBN(diff, self.curve)
def __mod__(self, other: Union[int, 'CurveBN']) -> 'CurveBN':
"""
Performs a BN_nnmod on two BIGNUMS.
"""
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, self.curve)
other = cast('CurveBN', other) # This is just for mypy
rem = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.BN_nnmod(rem, self.bignum, other.bignum, bn_ctx)
backend.openssl_assert(res == 1)
return CurveBN(rem, self.curve)
def __pow__(self, other):
"""
Performs a BN_mod_exp on two BIGNUMS.
WARNING: Only in constant time if BN_FLG_CONSTTIME is set on the BN.
"""
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, None, None, None)
power = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx, openssl._tmp_bn_mont_ctx(self.order) as bn_mont_ctx:
res = backend._lib.BN_mod_exp_mont(
power, self.bignum, other.bignum, self.order, bn_ctx, bn_mont_ctx
)
backend.openssl_assert(res == 1)
return CurveBN(power, self.curve_nid, self.group, self.order)
def hash(cls, *crypto_items, params=None):
params = params if params is not None else default_params()
curve_nid = backend._elliptic_curve_to_nid(params.curve)
order = openssl._get_ec_order_by_curve_nid(curve_nid)
group = openssl._get_ec_group_by_curve_nid(curve_nid)
# TODO: Clean this in an upcoming cleanup of pyUmbral
blake2b = hashes.Hash(hashes.BLAKE2b(64), backend=backend)
for item in crypto_items:
try:
item_bytes = item.to_bytes()
except AttributeError:
if isinstance(item, bytes):
item_bytes = item
else:
raise TypeError(
"{} is not acceptable type, received {}".format(
item, type(item)))
blake2b.update(item_bytes)
hash_digest = blake2b.finalize()
hash_digest = int.from_bytes(hash_digest,
byteorder='big',
signed=False)
hash_digest = openssl._int_to_bn(hash_digest)
_1 = backend._lib.BN_value_one()
order_minus_1 = openssl._get_new_BN()
res = backend._lib.BN_sub(order_minus_1, order, _1)
backend.openssl_assert(res == 1)
bignum = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.BN_mod(bignum, hash_digest, order_minus_1,
bn_ctx)
backend.openssl_assert(res == 1)
res = backend._lib.BN_add(bignum, bignum, _1)
backend.openssl_assert(res == 1)
return cls(bignum, curve_nid, group, order)
def from_int(cls, num, curve: ec.EllipticCurve = None):
"""
Returns a CurveBN object from a given integer on a curve.
By default, the underlying OpenSSL BIGNUM has BN_FLG_CONSTTIME set for
constant time operations.
"""
curve = curve if curve is not None else default_curve()
try:
curve_nid = backend._elliptic_curve_to_nid(curve)
except AttributeError:
# Presume that the user passed in the curve_nid
curve_nid = curve
group = openssl._get_ec_group_by_curve_nid(curve_nid)
order = openssl._get_ec_order_by_curve_nid(curve_nid)
conv_bn = openssl._int_to_bn(num, curve_nid)
return cls(conv_bn, curve_nid, group, order)
def __pow__(self, other : Union[int, 'CurveBN']) -> 'CurveBN':
"""
Performs a BN_mod_exp on two BIGNUMS.
WARNING: Only in constant time if BN_FLG_CONSTTIME is set on the BN.
"""
# TODO: Should this stay in or not?
if type(other) == int:
other = openssl._int_to_bn(other)
other = CurveBN(other, self.curve)
power = openssl._get_new_BN()
with backend._tmp_bn_ctx() as bn_ctx, openssl._tmp_bn_mont_ctx(self.curve.order) as bn_mont_ctx:
res = backend._lib.BN_mod_exp_mont(
power, self.bignum, other.bignum, self.curve.order, bn_ctx, bn_mont_ctx
)
backend.openssl_assert(res == 1)
return CurveBN(power, self.curve)
def from_bytes(cls, data: bytes, curve: Optional[Curve] = None) -> 'Point':
"""
Returns a Point object from the given byte data on the curve provided.
"""
curve = curve if curve is not None else default_curve()
compressed_size = cls.expected_bytes_length(curve)
# Check if compressed
if data[0] in [2, 3]:
if len(data) != compressed_size:
raise ValueError("X coordinate too large for curve.")
affine_x = int.from_bytes(data[1:], 'big')
affine_x = openssl._int_to_bn(affine_x, curve=None)
type_y = data[0] - 2
ec_point = openssl._get_new_EC_POINT(curve)
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.EC_POINT_set_compressed_coordinates_GFp(
curve.ec_group, ec_point, affine_x, type_y, bn_ctx)
backend.openssl_assert(res == 1)
return cls(ec_point, curve)
# Handle uncompressed point
# TODO: Give better error messages
elif data[0] == 4:
coord_size = compressed_size - 1
uncompressed_size = 1 + (2 * coord_size)
if len(data) != uncompressed_size:
raise ValueError(
"Uncompressed point does not have right size.")
affine_x = int.from_bytes(data[1:coord_size + 1], 'big')
affine_y = int.from_bytes(data[1 + coord_size:], 'big')
return cls.from_affine((affine_x, affine_y), curve)
else:
raise ValueError("Invalid point serialization.")
