package com.direnode.forgevotifier.cryptography;

import javax.xml.bind.DatatypeConverter;
import java.io.File;
import java.io.FileInputStream;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

public class RSARead{

        public static KeyPair load(String directory) throws Exception {
            // Read the public key file.
            File publicKeyFile = new File(directory + "/PublicKey.key");
            FileInputStream in = new FileInputStream(directory + "/PublicKey.key");
            byte[] encodedPublicKey = new byte[(int) publicKeyFile.length()];
            in.read(encodedPublicKey);
            encodedPublicKey = DatatypeConverter.parseBase64Binary(new String(encodedPublicKey));
            in.close();

            // Read the private key file.
            File privateKeyFile = new File(directory + "/PrivateKey.key");
            in = new FileInputStream(directory + "/PrivateKey.key");
            byte[] encodedPrivateKey = new byte[(int) privateKeyFile.length()];
            in.read(encodedPrivateKey);
            encodedPrivateKey = DatatypeConverter.parseBase64Binary(new String(encodedPrivateKey));
            in.close();

            // Instantiate and return the key pair.
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(encodedPublicKey);
            PublicKey publicKey = keyFactory.generatePublic(publicKeySpec);
            PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(encodedPrivateKey);
            PrivateKey privateKey = keyFactory.generatePrivate(privateKeySpec);
            return new KeyPair(publicKey, privateKey);
        }
}