I have read about EIP 155. I see that the main chain, test nets, and ETC were asked to implement EIP 155. If just ETH implemented EIP 155, wouldn't that have been enough to prevent ETC from being replayed and visa versa?

Second, if one is running the latest version of parity (1.5.3), has EIP 155 been implemented on both chains and splitter contracts no longer needed?

2 Answers 2


EIP-155 is optional, and performed by the wallet software. EIP-155 is only active for when the Chain ID is not 0.

A transaction that specifies a Chain ID of 0, that is signed by a private key can still be broadcast on any chain (so long as that address of that private key has a balance and the nonce is correct).

If a transaction is signed with Chain ID of 1, it will only work on the homestead (ETH) chain, so would not be repayable on ETC (at the time, the serializing format was completely incompatible with ETC anyways).

However, prior to ETC implementing EIP-155, the ETC transactions were still being signed by wallet software with Chain ID 0, so they would be repayable on ETH. So, it would have been enough to prevent ETH from being replayed on ETC, but not vice versa.

I purposely use Chain ID of 0 occasionally when I want to deploy the same contract to multiple networks, with the same contract address, since I can just broadcast the same transaction on each network.

If you are using parity as your wallet, then yes, you no longer need to worry about replay attacks, since they build EIP-155 transactions internally. But if you connect to your parity node with antique wallets, parity will still happily accept transactions with a Chain ID of 0. Any recent software should be safe though.


No, their protocols are now incompatible.

  • 1
    Welcome to Ethereum! Whilst this may theoretically answer the question, it would be preferable to include the essential parts of the answer here, and provide the link for reference.
    – q9f
    Commented Jun 7, 2017 at 10:44

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.