I want to be able to sign a transaction using my Defender Relay account and send the transaction privately to a mining pool using a service like Taichi https://taichi.network/#rpc
That is, I don't want the transaction to go into the mempool so it can be sandwich attacked.
The defender relay client does not implement the
signTransaction function on the signer.
Error: DefenderRelaySigner#signTransaction: method not yet supported
If it did, I could sign the transaction and then easily send the signed tx via Taichi.
I tried to work around this by encoding the transaction myself and signing using
signMessage but that doesn't work as
signMessage takes a hash of the message. To sign and Ethereum transaction, the digest is the keccak256 of the RLP encoded transaction, not the hash.