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package com.github.unclecatmyself.common.ssl;




import sun.security.x509.*;

import java.io.IOException;
import java.math.BigInteger;
import java.security.GeneralSecurityException;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.SecureRandom;
import java.security.cert.X509Certificate;
import java.util.Date;


/**
 * This class would require rt.jar in the class path in order to
 * generated it alternative is using keytool.
 */
public class X509CertTool {

    /**
     * Create a self-signed X.509 Certificate
     * @param dn the X.509 Distinguished Name, eg "CN=Test, L=London, C=GB"
     * @param pair the KeyPair
     * @param days how many days from now the Certificate is valid for
     * @param algorithm the signing algorithm, eg "SHA1withRSA"
     */
    @SuppressWarnings("restriction")
    X509Certificate generateCertificate(String dn, KeyPair pair, int days,
                                        String algorithm) throws GeneralSecurityException, IOException {
        PrivateKey privkey = pair.getPrivate();
        X509CertInfo info = new X509CertInfo();
        Date from = new Date();
        Date to = new Date(from.getTime() + days * 86400000l);
        CertificateValidity interval = new CertificateValidity(from, to);
        BigInteger sn = new BigInteger(64, new SecureRandom());
        X500Name owner = new X500Name(dn);

        info.set(X509CertInfo.VALIDITY, interval);
        info.set(X509CertInfo.SERIAL_NUMBER, new CertificateSerialNumber(sn));
        info.set(X509CertInfo.SUBJECT, new CertificateSubjectName(owner));
        info.set(X509CertInfo.ISSUER, new CertificateIssuerName(owner));
        info.set(X509CertInfo.KEY, new CertificateX509Key(pair.getPublic()));
        info.set(X509CertInfo.VERSION, new CertificateVersion(
                CertificateVersion.V3));
        AlgorithmId algo = new AlgorithmId(AlgorithmId.md5WithRSAEncryption_oid);
        info.set(X509CertInfo.ALGORITHM_ID, new CertificateAlgorithmId(algo));

        // Sign the cert to identify the algorithm that's used.
        X509CertImpl cert = new X509CertImpl(info);
        cert.sign(privkey, algorithm);

        // Update the algorith, and resign.
        algo = (AlgorithmId) cert.get(X509CertImpl.SIG_ALG);
        info.set(CertificateAlgorithmId.NAME + "."
                + CertificateAlgorithmId.ALGORITHM, algo);
        cert = new X509CertImpl(info);
        cert.sign(privkey, algorithm);
        return cert;
    }

    public static void main(String[] args) {

    }

}