49 lines
1.6 KiB
Python
49 lines
1.6 KiB
Python
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import random
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from typing import Tuple, Sequence, Generator
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from eth2spec.utils import bls
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from itertools import accumulate, repeat
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def __linear_combination(points, coeffs, zero=bls.Z1()):
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o = zero
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for point, coeff in zip(points, coeffs):
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o = bls.add(o, bls.multiply(point, coeff))
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return o
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# Verifies the integrity of a setup
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def verify_setup(setup) -> bool:
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g1_setup, g2_setup = setup
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g1_random_coefficients = [random.randrange(2**40) for _ in range(len(g1_setup) - 1)]
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g1_lower = __linear_combination(g1_setup[:-1], g1_random_coefficients, bls.Z1())
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g1_upper = __linear_combination(g1_setup[1:], g1_random_coefficients, bls.Z1())
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g2_random_coefficients = [random.randrange(2**40) for _ in range(len(g2_setup) - 1)]
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g2_lower = __linear_combination(g2_setup[:-1], g2_random_coefficients, bls.Z2())
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g2_upper = __linear_combination(g2_setup[1:], g2_random_coefficients, bls.Z2())
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return (
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g1_setup[0] == bls.G1() and
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g2_setup[0] == bls.G2() and
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bls.pairing_check([[g1_upper, bls.neg(g2_lower)], [g1_lower, g2_upper]])
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)
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def generate_one_sided_setup(length, secret, generator=bls.G1()):
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def __take(gen):
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return (next(gen) for _ in range(length))
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secrets = repeat(secret)
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return __take(accumulate(secrets, bls.multiply, initial=generator))
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# Generate a trusted setup with the given secret
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def generate_setup(
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g1_length,
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g2_length,
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secret
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) -> Tuple[Generator[bls.G1, None, None], Generator[bls.G2, None, None]]:
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return (
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generate_one_sided_setup(g1_length, secret, bls.G1()),
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generate_one_sided_setup(g2_length, secret, bls.G2()),
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)
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