bn128.py

from typing import List

from eth_account.messages import encode_defunct, _hash_eip191_message
from eth_utils import big_endian_to_int

from fastecdsa.curve import Curve
from fastecdsa import keys, ecdsa

P = 0x2523648240000001ba344d80000000086121000000000013a700000000000013
N = 0x2523648240000001ba344d8000000007ff9f800000000010a10000000000000d

BN128 = Curve(
    name='BN128',
    p=P,
    a=0,
    b=2,
    q=N,
    gx=0x2523648240000001ba344d80000000086121000000000013a700000000000012,
    gy=1,
)

hex_message = '0x49e299a55346'
message = encode_defunct(hexstr=hex_message)
message_hash = _hash_eip191_message(message)

priv_key = 6085657696930404735701793182981912633161924824257970801516674368760204638101
pub_key = keys.get_public_key(priv_key, BN128)

# Sign message
r, s = ecdsa.sign(message_hash, priv_key, prehashed=True)
z = big_endian_to_int(message_hash)

# Verify signature
valid = ecdsa.verify((r, s), message_hash, pub_key, curve=BN128, prehashed=True)
print(valid)

# Encode into BigInt3
def split(num: int) -> List[int]:
    """
    Takes a 256-bit integer and returns its canonical representation as:
        d0 + BASE * d1 + BASE**2 * d2,
    where BASE = 2**86.
    """
    BASE = 2 ** 86
    a = []
    for _ in range(3):
        num, residue = divmod(num, BASE)
        a.append(hex(residue))
    assert num == 0
    return a

print("pub_key:", split(pub_key.x), split(pub_key.y))
print("r:", split(r))
print("s:", split(s))
print("msg_hash:", split(z))