Given an RSA SHA256 signature (obtained from encrypting a hash using an RSA Private Key), I must assert whether a provided Public Key matches this signature or not.
It is imperative that this verification occurs inside a smart contract. I haven't, however, had much luck in finding implementations of, effectively, the RSA decrypt algorithm for Ethereum smart contracts.
In case that it hasn't been done, which all points out to, what would be the best way to go about building this? As a last resort I have considered using an oracle, however that carries a lot of security risks that I wouldn't want to be meddling with.