The created recoverable ECDSA signature differs from the results of other libraries.

[lanlingxiawu]

Ethers Version

6.12.0

Search Terms

No response

Describe the Problem

The result generated when creating the recoverable ECDSA signature is different from the result generated using Python. Is there a way to generate the same result?

Code Snippet

ethers.js
    const rawhex1 = "0xf8ad82e69c85012a05f200830329189455d398326f99059ff775485246999027b319795580b844a9059cbb0000000000000000000000006df68f71f19081751850160118fc755bfeb036120000000000000000000000000000000000000000000000056bc75e2d631000008193a0ade014e655a2d1645efb5f37a142c2369ab96d2d962861dd353fa33fe15b76cda041b291fb742d07c0d475cb2611e9dd6010bbd052c79f99e73c7f9e3653afb6f7";
    const rawhex2 = "0xf8ec8307f58584b8c6fe72830927c094bddbcbaa9cf9603b7055aad963506ede71692f1280b8830000000300000000000000000000000000000000000000000000000087250559b9145f9000000000000000000000000000000000000000000000011f35cc4934f0b52a80bb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c55d398326f99059ff775485246999027b319795500006400000000000000000af935e000000000000000008193a0f63bed83d054bdecfb6852f980ed62f35922fe5b68296b603b290a3eff41fabea04b73872c7e68f541bc97eba52abf956eac4a0e198b762e1f9a872336f6748eed";

    const hash1 = ethers.keccak256(rawhex1);
    const hash2 = ethers.keccak256(rawhex2);
    console.log("hash1: ", hash1);
    console.log("hash2: ", hash2);

    const signer = new ethers.SigningKey("0x48acf19375e8a27309fe5394728abc2eb6d5a0a4feb6b6c53207ca1c256a6739");
    const result = ethers.concat([hash1, hash2]);
    const signature = signer.sign(ethers.keccak256(result));
    console.log("sign: ", signature.serialized);


out:
sign:  0x83e4b3a6af20e58315554b5bc38a8398cfca44a75d42973a4454378b0dc9cae63c229b52341d1ddfc4e3ad4360e518c1f1363e2d21fcba507e8e2e10e266edd21c


python:
from web3 import Web3
from coincurve import PrivateKey

hex_raw_transaction1 = '0xf8ad82e69c85012a05f200830329189455d398326f99059ff775485246999027b319795580b844a9059cbb0000000000000000000000006df68f71f19081751850160118fc755bfeb036120000000000000000000000000000000000000000000000056bc75e2d631000008193a0ade014e655a2d1645efb5f37a142c2369ab96d2d962861dd353fa33fe15b76cda041b291fb742d07c0d475cb2611e9dd6010bbd052c79f99e73c7f9e3653afb6f7'
hex_raw_transaction2 = '0xf8ec8307f58584b8c6fe72830927c094bddbcbaa9cf9603b7055aad963506ede71692f1280b8830000000300000000000000000000000000000000000000000000000087250559b9145f9000000000000000000000000000000000000000000000011f35cc4934f0b52a80bb4cdb9cbd36b01bd1cbaebf2de08d9173bc095c55d398326f99059ff775485246999027b319795500006400000000000000000af935e000000000000000008193a0f63bed83d054bdecfb6852f980ed62f35922fe5b68296b603b290a3eff41fabea04b73872c7e68f541bc97eba52abf956eac4a0e198b762e1f9a872336f6748eed'
private_key_hex = '48acf19375e8a27309fe5394728abc2eb6d5a0a4feb6b6c53207ca1c256a6739'

tx1_hash = Web3.keccak(Web3.to_bytes(hexstr=hex_raw_transaction1))
tx2_hash = Web3.keccak(Web3.to_bytes(hexstr=hex_raw_transaction2))

print("tx1_hash:", tx1_hash.hex())
print("tx2_hash:", tx2_hash.hex())
print("tx1_hash + tx2_hash:", Web3.keccak(tx1_hash + tx2_hash).hex())

private_key = PrivateKey(bytes.fromhex(private_key_hex))
signature = private_key.sign_recoverable(Web3.keccak(tx1_hash + tx2_hash), hasher=None)
print("signature:", signature.hex())


out:
signature: 83e4b3a6af20e58315554b5bc38a8398cfca44a75d42973a4454378b0dc9cae63c229b52341d1ddfc4e3ad4360e518c1f1363e2d21fcba507e8e2e10e266edd201

Contract ABI

Errors

Environment

No response

Environment (Other)

No response

[ricmoo]

It looks like the signature you are getting from Python is using a non-standard signature format.

The final byte (last 2 nibbles) should be either 1b or 1c depending on whether the recovery parameter is 0 or 1, which you are getting 01, my guess is that is the recovery parameters was 0 you would get 00 in the Python library.

As a quick background, the recovery parameter is an artifact that a signature can be in either the "top" or "bottom" half of the elliptic curve, so it is used to indicate which to choose. The standard uses 27 + recoveryParam, which in hex yields 0x1b (i.e. 27) when recoveryParam is 0 and 0x1c (i.e. 28) when the recoveryParam is 1. This is left-over from Bitcoin where they used select bases for various things to try being non-ambiguous (for example, similarly compressed public keys use a prefix of 0x02 and 0x03 to differentiate between the "top" and "bottom" of the curve for public keys, use 0x04 to indicate uncompressed public keys, 0x05 to indicate encrypted private keys, etc.).

So, I think to convert the Python to be standards compliant, you can use the following Python code to convert your python signature: sig[0:-2] + ["1b", "1c"][int(sig[-2], 16)]

Or to convert the output of Ethers to match the output of Python: sig.substring(0, sig.length - 2) + '0' + String(parseInt(sig.substring(sig.length - 2), 16) - 27)

Let me know if that helps.

(Moving to discussions)