/*
 * DBeaver - Universal Database Manager
 * Copyright (C) 2010-2017 Serge Rider (serge@jkiss.org)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jkiss.dbeaver.model.impl.app;

import org.jkiss.utils.Base64;
import sun.security.util.DerInputStream;
import sun.security.util.DerValue;

import java.io.IOException;
import java.math.BigInteger;
import java.security.GeneralSecurityException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.RSAPrivateCrtKeySpec;

/**
 * Extracted to a separate class because of usage of internal API.
 */
class PKCS1Util {

    public static PrivateKey loadPrivateKeyFromPKCS1(String privateKeyPem) throws GeneralSecurityException, IOException {
        DerInputStream derReader = new DerInputStream(Base64.decode(privateKeyPem));

        DerValue[] seq = derReader.getSequence(0);

        if (seq.length < 9) {
            throw new GeneralSecurityException("Could not parse a PKCS1 private key.");
        }

        // skip version seq[0];
        BigInteger modulus = seq[1].getBigInteger();
        BigInteger publicExp = seq[2].getBigInteger();
        BigInteger privateExp = seq[3].getBigInteger();
        BigInteger prime1 = seq[4].getBigInteger();
        BigInteger prime2 = seq[5].getBigInteger();
        BigInteger exp1 = seq[6].getBigInteger();
        BigInteger exp2 = seq[7].getBigInteger();
        BigInteger crtCoef = seq[8].getBigInteger();

        RSAPrivateCrtKeySpec keySpec = new RSAPrivateCrtKeySpec(modulus, publicExp, privateExp, prime1, prime2, exp1, exp2, crtCoef);

        KeyFactory factory = KeyFactory.getInstance("RSA");

        return factory.generatePrivate(keySpec);
    }

}