ethereum.crypto.elliptic_curve

Elliptic Curves ^^^^^^^^^^^^^^^

SECP256K1B

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SECP256K1B = U256(7)

SECP256K1P

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SECP256K1P = U256(
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    0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F
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)

SECP256K1N

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SECP256K1N = U256(
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    0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141
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)

secp256k1_recover

Recovers the public key from a given signature.

Parameters

r : TODO s : TODO v : TODO msg_hash : Hash of the message being recovered.

Returns

public_key : ethereum.base_types.Bytes Recovered public key.

def secp256k1_recover(​r: U256, ​​s: U256, ​​v: U256, ​​msg_hash: Hash32​) -> Bytes:
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    """
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    Recovers the public key from a given signature.
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    Parameters
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    ----------
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    r :
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        TODO
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    s :
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        TODO
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    v :
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        TODO
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    msg_hash :
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        Hash of the message being recovered.
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    Returns
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    -------
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    public_key : `ethereum.base_types.Bytes`
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        Recovered public key.
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    """
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    is_square = pow(
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        pow(r, U256(3), SECP256K1P) + SECP256K1B,
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        (SECP256K1P - U256(1)) // U256(2),
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        SECP256K1P,
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    )
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    if is_square != 1:
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        raise InvalidSignatureError(
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            "r is not the x-coordinate of a point on the secp256k1 curve"
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        )
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    r_bytes = r.to_be_bytes32()
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    s_bytes = s.to_be_bytes32()
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    signature = bytearray([0] * 65)
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    signature[32 - len(r_bytes) : 32] = r_bytes
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    signature[64 - len(s_bytes) : 64] = s_bytes
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    signature[64] = v
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    # If the recovery algorithm returns the point at infinity,
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    # the signature is considered invalid
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    # the below function will raise a ValueError.
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    try:
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        public_key = coincurve.PublicKey.from_signature_and_message(
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            bytes(signature), msg_hash, hasher=None
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        )
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    except ValueError as e:
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        raise InvalidSignatureError from e
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    public_key = public_key.format(compressed=False)[1:]
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    return public_key