How to get legacy address and private key from Segwit P2SH address? I have a Segwit P2SH address (starting with 3...) with the corresponding private key and need to obtain the legacy address (starting with 1...) and the private key. Is this possible?
You have the private key so you can just derive the address from there. Get the corresponding public key, hash it with SHA256 and then that result with RIPEMD160. Then perform Base58Check Encoding on it.