def normalize(self):
if int(self.z) in (0, 1):
return self
z = GField(modular_inverse(int(self.z), self.ecc_params.P),
self.ecc_params)
tmp = z.sqr()
x = self.x.mul(tmp)
y = self.y.mul(tmp).mul(z)
z = 1
return Jacobian(x, y, z, self.ecc_params)
def parse(s, ecc_params=_ecc_params):
"""Takes a 192 bit integer in hex with a + or - sign on the front and
returns a Jacobian object."""
assert s[0] in ("-", "+")
ybit, s = s[0] == "-", s[1:]
x = GField(int(s, 16), ecc_params)
_ = x.mul2().add(x)
y2 = x.pow(3).sub(x.mul(3)).add(ecc_params.B)
y = y2.legendre_sqrt()
if y is None:
y = 0
if bit_test(y, 0) != ybit:
y = -y
z = 1
return Jacobian(x, y, z, ecc_params)
def generate_challenge(public_key, ecc_params=ecc_params):
if isinstance(public_key, str):
public_key = parse_public_key(public_key, ecc_params)
assert isinstance(public_key, Jacobian)
secret = GField(get_random_number(24), ecc_params)
challenge = Jacobian.base(ecc_params).mul(secret).normalize()
answer = public_key.mul(secret).normalize().x
return (challenge, answer)
def __init__(self, x, y, z, ecc_params=_ecc_params):
self.ecc_params = ecc_params
self._x = GField(x)
self._y = GField(y)
self._z = GField(z)
def generate_key_pair(ecc_params=ecc_params):
private_key = GField(get_random_number(24), ecc_params)
public_key = get_public_key(private_key)
return (private_key, public_key)
def parse_private_key(private_key_str, ecc_params=ecc_params):
private_key = int(private_key_str, 16)
return GField(private_key, ecc_params)