def public_key_to_coords(public_key):
length = len(public_key)
if length == 33:
flag, x = int.from_bytes(public_key[:1], 'big'), int.from_bytes(public_key[1:], 'big')
y = x_to_y(x, flag & 1)
elif length == 65:
x, y = int.from_bytes(public_key[1:33], 'big'), int.from_bytes(public_key[33:], 'big')
else:
raise ValueError('{} is an invalid length for a public key.'.format(length))
return x, y
def test_x_to_y_correct_first_solution(self):
assert x_to_y(X_CORRECT, Y_CORRECT & 1) == Y_CORRECT