Q: who is the proof producer for WithdrawResults?

[olga24912]

For finalizing withdrawing Eth on Ethereum side in EthCustodian contract we check the proof producer of the WithdrawResult: https://github.com/aurora-is-near/eth-connector/blob/master/eth-custodian/contracts/ProofKeeper.sol#L74

According to that line, where we create the address for depositing Eth to Aurora, the nearProofProducerAccount is expected to be nearSDK ~ aurora-engine (aurora and etc): https://github.com/aurora-is-near/eth-connector/blob/master/eth-custodian/contracts/EthCustodian.sol#L68

We have two ways to withdraw Eth from Near: call the withdraw function at aurora-engine(it redirect the function call to the engine-withdraw function in aurora-eth-connector), or call the withdraw function directly at aurora-eth-connector. I am not sure who will be the WithdrawResult producer in the first case, but in the second case it is aurora-eth-connector. I guess in the first case it is aurora-eth-connector as well, not the aurora-engine. https://github.com/aurora-is-near/aurora-eth-connector/blob/master/eth-connector/src/lib.rs#L504

In that case, we broke the backward compatibility because some contracts (for example EthCustodian) can expect that the WithdrawResult is produced by aurora-engine.

[mrLSD]

In Engine, we have precompiles: ExitToEthereum, ExitToNear. It's about withdraw producers.

And for Engine we have special method in aurora-eth-connector - engine_withdraw. In the future Engine precompiles will call directly aurora-eth-connector.

I can't see where logic is broken.

[karim-en]

@mrLSD The problem is that on eth side we have just one field to store the near-side account , it is used for both withdraw and deposit actions.
The nearProofProducerAccount will be changed from aurora to a new account eg. eth-connector.aurora, so, in this case, the method depositToEVM produces a message eth-connector.aurora:ETH_ADDRESS here.

For backward compatibility, it is better to handle this case by adding a check on the eth connector near-side:

correct_receiver_id = if receiver_id == current_account_id() {
  return parent of current_account_id() or EVM account id from storage (`aurora`), or hardcoded `aurora`.
}