Verification of externally created ECDSA signatures in Solidity
We create ECDSA signatures in Golang, and perform the verification in Solidity. This gist is based on a solution from https://ethereum.stackexchange.com/questions/55474/verification-of-externally-created-ecdsa-signatures-in-solidity/55487#55487, and on helper methods from https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/ECRecovery.sol.
How to use
First, run the Golang code to produce the address and signature. Then, copy-paste the printed values into the verify method of the Solidity contract.