def from_bytes(cls, capsule_bytes: bytes, curve: ec.EllipticCurve = None):
"""
Instantiates a Capsule object from the serialized data.
"""
curve = curve if curve is not None else default_curve()
key_size = get_curve_keysize_bytes(curve)
capsule_buff = BytesIO(capsule_bytes)
# BigNums are the keysize in bytes, Points are compressed and the
# keysize + 1 bytes long.
if len(capsule_bytes) == 197:
eph_e = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
eph_v = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
sig = BigNum.from_bytes(capsule_buff.read(key_size), curve)
e_prime = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
v_prime = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
eph_ni = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
else:
eph_e = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
eph_v = Point.from_bytes(capsule_buff.read(key_size + 1), curve)
sig = BigNum.from_bytes(capsule_buff.read(key_size), curve)
e_prime = v_prime = eph_ni = None
return cls(point_eph_e=eph_e,
point_eph_v=eph_v,
bn_sig=sig,
e_prime=e_prime,
v_prime=v_prime,
noninteractive_point=eph_ni)
def from_bytes(data: bytes, curve: ec.EllipticCurve = None):
"""
Instantiate a KFrag object from the serialized data.
"""
curve = curve if curve is not None else default_curve()
key_size = get_curve_keysize_bytes(curve)
data = BytesIO(data)
# BigNums are the keysize in bytes, Points are compressed and the
# keysize + 1 bytes long.
id = BigNum.from_bytes(data.read(key_size), curve)
key = BigNum.from_bytes(data.read(key_size), curve)
eph_ni = Point.from_bytes(data.read(key_size + 1), curve)
commitment = Point.from_bytes(data.read(key_size + 1), curve)
sig1 = BigNum.from_bytes(data.read(key_size), curve)
sig2 = BigNum.from_bytes(data.read(key_size), curve)
return KFrag(id, key, eph_ni, commitment, sig1, sig2)
def from_bytes(cls, data: bytes, curve: ec.EllipticCurve = None):
"""
Instantiate ChallengeResponse from serialized data.
"""
curve = curve if curve is not None else default_curve()
key_size = get_curve_keysize_bytes(curve)
data = BytesIO(data)
# BigNums are the keysize in bytes, Points are compressed and the
# keysize + 1 bytes long.
e2 = Point.from_bytes(data.read(key_size + 1), curve)
v2 = Point.from_bytes(data.read(key_size + 1), curve)
kfrag_commitment = Point.from_bytes(data.read(key_size + 1), curve)
kfrag_pok = Point.from_bytes(data.read(key_size + 1), curve)
kfrag_sig1 = BigNum.from_bytes(data.read(key_size), curve)
kfrag_sig2 = BigNum.from_bytes(data.read(key_size), curve)
sig = BigNum.from_bytes(data.read(key_size), curve)
return cls(e2, v2, kfrag_commitment, kfrag_pok, kfrag_sig1, kfrag_sig2,
sig)
def from_bytes(data: bytes, curve: ec.EllipticCurve = None):
"""
Instantiates a CapsuleFrag object from the serialized data.
"""
curve = curve if curve is not None else default_curve()
key_size = get_curve_keysize_bytes(curve)
data = BytesIO(data)
# BigNums are the keysize in bytes, Points are compressed and the
# keysize + 1 bytes long.
e1 = Point.from_bytes(data.read(key_size + 1), curve)
v1 = Point.from_bytes(data.read(key_size + 1), curve)
kfrag_id = BigNum.from_bytes(data.read(key_size), curve)
eph_ni = Point.from_bytes(data.read(key_size + 1), curve)
return CapsuleFrag(e1, v1, kfrag_id, eph_ni)
def from_bytes(cls, data, curve: ec.EllipticCurve = None):
"""
Returns a Point object from the given byte data on the curve provided.
"""
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
# Check if compressed
if data[0] in [2, 3]:
type_y = data[0] - 2
if len(data[1:]) > get_curve_keysize_bytes(curve):
raise ValueError("X coordinate too large for curve.")
affine_x = BigNum.from_bytes(data[1:], curve)
ec_point = backend._lib.EC_POINT_new(affine_x.group)
backend.openssl_assert(ec_point != backend._ffi.NULL)
ec_point = backend._ffi.gc(ec_point,
backend._lib.EC_POINT_clear_free)
with backend._tmp_bn_ctx() as bn_ctx:
res = backend._lib.EC_POINT_set_compressed_coordinates_GFp(
affine_x.group, ec_point, affine_x.bignum, type_y, bn_ctx)
backend.openssl_assert(res == 1)
return cls(ec_point, curve_nid, affine_x.group)
# Handle uncompressed point
elif data[0] == 4:
key_size = get_curve_keysize_bytes(curve)
affine_x = int.from_bytes(data[1:key_size + 1], 'big')
affine_y = int.from_bytes(data[1 + key_size:], 'big')
return Point.from_affine((affine_x, affine_y), curve)
else:
raise ValueError("Invalid point serialization.")
def from_bytes(cls,
key_bytes: bytes,
params: UmbralParameters = None,
password: bytes = None,
_scrypt_cost: int = 20,
decoder: Callable = None):
"""
Loads an Umbral private key from bytes.
Optionally, allows a decoder function to be passed as a param to decode
the data provided before converting to an Umbral key.
Optionally, if a password is provided it will decrypt the key using
nacl's Salsa20-Poly1305 and Scrypt key derivation.
WARNING: RFC7914 recommends that you use a 2^20 cost value for sensitive
files. Unless you changed this when you called `to_bytes`, you should
not change it here. It is NOT recommended to change the `_scrypt_cost`
value unless you know what you're doing.
"""
if params is None:
params = default_params()
if decoder:
key_bytes = decoder(key_bytes)
if password:
salt = key_bytes[-16:]
key_bytes = key_bytes[:-16]
key = Scrypt(salt=salt,
length=SecretBox.KEY_SIZE,
n=2**_scrypt_cost,
r=8,
p=1,
backend=default_backend()).derive(password)
key_bytes = SecretBox(key).decrypt(key_bytes)
bn_key = BigNum.from_bytes(key_bytes, params.curve)
return cls(bn_key, params)
def test_point_curve_mult_regression():
k256_point_bytes = b'\x03\xe0{\x1bQ\xbf@\x1f\x95\x8d\xe1\x17\xa7\xbe\x9e-G`T\xbf\xd7\x9e\xa7\x10\xc8uA\xc0z$\xc0\x92\x8a'
k256_bn_bytes = b'4u\xd70-\xa0h\xdeG\xf0\x143\x06!\x91\x05{\xe4jC\n\xf1h\xed7a\xf8\x9d\xec^\x19\x8c'
k256_point = Point.from_bytes(k256_point_bytes)
k256_bn = BigNum.from_bytes(k256_bn_bytes)
product_with_star_operator = k256_point * k256_bn
# Make sure we have instantiated a new, unequal point in the same curve and group
assert isinstance(product_with_star_operator,
Point), "Point.__mul__ did not return a point instance"
assert k256_point != product_with_star_operator
assert k256_point.curve_nid == product_with_star_operator.curve_nid
assert k256_point.group == product_with_star_operator.group
product_bytes = b'\x03\xc9\xda\xa2\x88\xe2\xa0+\xb1N\xb6\xe6\x1c\xa5(\xe6\xe0p\xf6\xf4\xa9\xfc\xb1\xfaUV\xd3\xb3\x0e4\x94\xbe\x12'
product_point = Point.from_bytes(product_bytes)
assert product_with_star_operator.to_bytes() == product_bytes
assert product_point == product_with_star_operator
# Repeating the operation, should return the same result.
product_with_star_operator_again = k256_point * k256_bn
assert product_with_star_operator == product_with_star_operator_again