mirror of https://github.com/nucypher/pyUmbral.git
Use arg packing in hash_to_bn and check if item is bytes before hashing
Use default_paramspull/118/head
tuxxy
parent
0fd530b74f
commit
4a244a01a3
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@ -4,7 +4,7 @@ from cryptography.hazmat.backends.openssl import backend
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from cryptography.hazmat.primitives.asymmetric import ec
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from cryptography.hazmat.primitives import hashes
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from umbral.config import default_curve
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from umbral.config import default_curve, default_params
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from umbral.utils import get_curve_keysize_bytes
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@ -82,14 +82,20 @@ class BigNum(object):
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return cls(bignum, curve_nid, group, order)
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@classmethod
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def hash_to_bn(cls, crypto_items, params):
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def hash_to_bn(cls, *crypto_items, params=None):
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params = params if params is not None else default_params()
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blake2b = hashes.Hash(hashes.BLAKE2b(64), backend=backend)
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for item in crypto_items:
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try:
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data_bytes = item.to_bytes()
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except AttributeError:
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data_bytes = item
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blake2b.update(data_bytes)
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if isinstance(item, bytes):
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data_bytes = item
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else:
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raise TypeError("{} is not bytes, got {} instead.".format(item, type(item)))
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else:
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blake2b.update(data_bytes)
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i = 0
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h = 0
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@ -99,9 +105,10 @@ class BigNum(object):
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hash_digest = blake2b_i.finalize()
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h = int.from_bytes(hash_digest, byteorder='big', signed=False)
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i += 1
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hash_bn = h % int(params.order)
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hash_bn = h % int(params.order)
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res = cls.from_int(hash_bn, params.curve)
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return res
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@classmethod
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@ -1,6 +1,6 @@
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from cryptography.hazmat.primitives.asymmetric import ec
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from umbral.bignum import BigNum, hash_to_bn
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from umbral.bignum import BigNum
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from umbral.config import default_curve, default_params
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from umbral.point import Point
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from umbral.utils import get_curve_keysize_bytes
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@ -66,7 +66,7 @@ class KFrag(object):
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# We check the Schnorr signature over the kfrag components
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g_y = (z2 * params.g) + (z1 * pub_a)
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check_kfrag_2 = z1 == hash_to_bn([g_y, self.bn_id, pub_a, pub_b, u1, x], params)
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check_kfrag_2 = z1 == BigNum.hash_to_bn(g_y, self.bn_id, pub_a, pub_b, u1, x, params=params)
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return check_kfrag_1 & check_kfrag_2
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@ -15,7 +15,7 @@ from cryptography.hazmat.primitives.kdf.hkdf import HKDF
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from umbral.config import default_params
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from umbral.point import Point
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from umbral.bignum import BigNum, hash_to_bn
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from umbral.bignum import BigNum
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from umbral.params import UmbralParameters
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@ -285,17 +285,17 @@ class UmbralKeyingMaterial(object):
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Derives an UmbralPrivateKey using a KDF from this instance of
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UmbralKeyingMaterial, a label, and an optional salt.
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"""
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if params is None:
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params = default_params()
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params = params if params is not None else default_params()
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hkdf = HKDF(algorithm=hashes.BLAKE2b(64),
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length=64,
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salt=salt,
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info=b"NuCypherKMS/KeyDerivation/"+label,
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backend=default_backend()
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)
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key_material = HKDF(
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algorithm=hashes.BLAKE2b(64),
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length=64,
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salt=salt,
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info=b"NuCypherKMS/KeyDerivation/"+label,
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backend=default_backend()
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).derive(self.keying_material)
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bn_key = hash_to_bn([hkdf.derive(self.keying_material)], params)
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bn_key = BigNum.hash_to_bn(key_material, params=params)
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return UmbralPrivateKey(bn_key, params)
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@classmethod
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@ -6,7 +6,7 @@ from cryptography.hazmat.backends.openssl import backend
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from cryptography.hazmat.primitives.asymmetric import ec
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from cryptography.hazmat.primitives import hashes
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from umbral.bignum import BigNum, hash_to_bn
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from umbral.bignum import BigNum
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from umbral.config import default_params, default_curve
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from umbral.dem import UmbralDEM
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from umbral.fragments import KFrag, CapsuleFrag
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@ -107,7 +107,7 @@ class Capsule(object):
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e = self._point_eph_e
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v = self._point_eph_v
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s = self._bn_sig
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h = hash_to_bn([e, v], params)
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h = BigNum.hash_to_bn(e, v, params=params)
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return s * params.g == v + (h * e)
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@ -145,16 +145,16 @@ class Capsule(object):
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id_cfrag_pairs = list(self._attached_cfrags.items())
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id_0, cfrag_0 = id_cfrag_pairs[0]
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x_0 = hash_to_bn([id_0, hashed_dh_tuple], params)
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x_0 = BigNum.hash_to_bn(id_0, hashed_dh_tuple, params=params)
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if len(id_cfrag_pairs) > 1:
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xs = [hash_to_bn([_id, hashed_dh_tuple], params)
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xs = [BigNum.hash_to_bn(_id, hashed_dh_tuple, params=params)
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for _id in self._attached_cfrags.keys()]
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lambda_0 = lambda_coeff(x_0, xs)
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e = lambda_0 * cfrag_0.point_eph_e1
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v = lambda_0 * cfrag_0.point_eph_v1
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for id_i, cfrag in id_cfrag_pairs[1:]:
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x_i = hash_to_bn([id_i, hashed_dh_tuple], params)
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x_i = BigNum.hash_to_bn(id_i, hashed_dh_tuple, params=params)
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lambda_i = lambda_coeff(x_i, xs)
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e = e + (lambda_i * cfrag.point_eph_e1)
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v = v + (lambda_i * cfrag.point_eph_v1)
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@ -280,7 +280,7 @@ def split_rekey(priv_a: Union[UmbralPrivateKey, BigNum],
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x = BigNum.gen_rand(params.curve)
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xcomp = x * g
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d = hash_to_bn([xcomp, pub_b, pub_b * x], params)
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d = BigNum.hash_to_bn(xcomp, pub_b, pub_b * x, params=params)
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coeffs = [priv_a * (~d)]
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coeffs += [BigNum.gen_rand(params.curve) for _ in range(threshold - 1)]
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@ -299,14 +299,14 @@ def split_rekey(priv_a: Union[UmbralPrivateKey, BigNum],
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for _ in range(N):
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id_kfrag = BigNum.gen_rand(params.curve)
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share_x = hash_to_bn([id_kfrag, hashed_dh_tuple], params)
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share_x = BigNum.hash_to_bn(id_kfrag, hashed_dh_tuple, params=params)
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rk = poly_eval(coeffs, share_x)
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u1 = rk * u
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y = BigNum.gen_rand(params.curve)
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z1 = hash_to_bn([y * g, id_kfrag, pub_a, pub_b, u1, xcomp], params)
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z1 = BigNum.hash_to_bn(y * g, id_kfrag, pub_a, pub_b, u1, xcomp, params=params)
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z2 = y - priv_a * z1
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kfrag = KFrag(id_=id_kfrag, key=rk, x=xcomp, u1=u1, z1=z1, z2=z2)
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@ -351,8 +351,8 @@ def _challenge(kfrag: KFrag, capsule: Capsule,
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hash_input = [e, e1, e2, v, v1, v2, u, u1, u2]
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if challenge_metadata is not None:
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hash_input.append(challenge_metadata)
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h = hash_to_bn(hash_input, params)
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h = BigNum.hash_to_bn(*hash_input, params=params)
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z3 = t + h * kfrag.bn_key
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@ -400,9 +400,9 @@ def _check_challenge(capsule: Capsule, cfrag: CapsuleFrag,
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if challenge_metadata is not None:
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hash_input.append(challenge_metadata)
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h = hash_to_bn(hash_input, params)
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h = BigNum.hash_to_bn(hash_input, params=params)
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check31 = z1 == hash_to_bn([g_y, kfrag_id, pub_a, pub_b, u1, xcomp], params)
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check31 = z1 == BigNum.hash_to_bn(g_y, kfrag_id, pub_a, pub_b, u1, xcomp, params=params)
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check32 = z3 * e == e2 + (h * e1)
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check33 = z3 * u == u2 + (h * u1)
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check34 = z3 * v == v2 + (h * v1)
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@ -423,7 +423,7 @@ def _encapsulate(alice_pub_key: Point, key_length=32,
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priv_u = BigNum.gen_rand(params.curve)
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pub_u = priv_u * g
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h = hash_to_bn([pub_r, pub_u], params)
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h = BigNum.hash_to_bn(pub_r, pub_u, params=params)
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s = priv_u + (priv_r * h)
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shared_key = (priv_r + priv_u) * alice_pub_key
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@ -457,7 +457,7 @@ def _decapsulate_reencrypted(pub_key: Point, priv_key: BigNum,
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params = params if params is not None else default_params()
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xcomp = capsule._point_noninteractive
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d = hash_to_bn([xcomp, pub_key, priv_key * xcomp], params)
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d = BigNum.hash_to_bn(xcomp, pub_key, priv_key * xcomp, params=params)
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e_prime = capsule._point_eph_e_prime
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v_prime = capsule._point_eph_v_prime
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@ -469,7 +469,7 @@ def _decapsulate_reencrypted(pub_key: Point, priv_key: BigNum,
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e = capsule._point_eph_e
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v = capsule._point_eph_v
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s = capsule._bn_sig
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h = hash_to_bn([e, v], params)
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h = BigNum.hash_to_bn(e, v, params=params)
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inv_d = ~d
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if not (s*inv_d) * orig_pub_key == (h*e_prime) + v_prime:
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