public DistinguishedNameValues() {
    put(BCStyle.C,null);
    put(BCStyle.ST,null);
    put(BCStyle.L,null);
    put(BCStyle.STREET,null);
    put(BCStyle.O,null);
    put(BCStyle.OU,null);
    put(BCStyle.CN,null);
}
 

static void initialiseCertificate(Context c, KeyPair keyPair){
    Calendar calendar = Calendar.getInstance();
    calendar.add(Calendar.DAY_OF_MONTH, -1);
    Date notBefore = calendar.getTime();
    calendar.add(Calendar.YEAR, 10);
    Date notAfter = calendar.getTime();

    X500NameBuilder nameBuilder = new X500NameBuilder(BCStyle.INSTANCE);
    nameBuilder.addRDN(BCStyle.CN, "an2linuxclient");
    nameBuilder.addRDN(BCStyle.SERIALNUMBER, new BigInteger(128, new Random()).toString(16));

    X509v3CertificateBuilder certificateBuilder = new JcaX509v3CertificateBuilder(
            nameBuilder.build(),
            BigInteger.ONE,
            notBefore, notAfter,
            nameBuilder.build(),
            keyPair.getPublic()
    );
    try {
        ContentSigner contentSigner = new JcaContentSignerBuilder("SHA256WithRSAEncryption").build(keyPair.getPrivate());
        X509Certificate certificate = new JcaX509CertificateConverter().getCertificate(certificateBuilder.build(contentSigner));

        SharedPreferences deviceKeyPref = c.getSharedPreferences(
                c.getString(R.string.device_key_and_cert), MODE_PRIVATE);
        deviceKeyPref.edit().putString(c.getString(R.string.certificate),
                Base64.encodeToString(certificate.getEncoded(), Base64.NO_WRAP)).apply();
        Log.d("TlsHelper", "Generated new certificate successfully");
    } catch (Exception e){
        Log.e("TlsHelper", "initialiseCertificate");
        Log.e("StackTrace", Log.getStackTraceString(e));
    }
}
 

static void initialiseCertificate(Context c, KeyPair keyPair){
    Calendar calendar = Calendar.getInstance();
    calendar.add(Calendar.DAY_OF_MONTH, -1);
    Date notBefore = calendar.getTime();
    calendar.add(Calendar.YEAR, 10);
    Date notAfter = calendar.getTime();

    X500NameBuilder nameBuilder = new X500NameBuilder(BCStyle.INSTANCE);
    nameBuilder.addRDN(BCStyle.CN, "an2linuxclient");
    nameBuilder.addRDN(BCStyle.SERIALNUMBER, new BigInteger(128, new Random()).toString(16));

    X509v3CertificateBuilder certificateBuilder = new JcaX509v3CertificateBuilder(
            nameBuilder.build(),
            BigInteger.ONE,
            notBefore, notAfter,
            nameBuilder.build(),
            keyPair.getPublic()
    );
    try {
        ContentSigner contentSigner = new JcaContentSignerBuilder("SHA256WithRSAEncryption").build(keyPair.getPrivate());
        X509Certificate certificate = new JcaX509CertificateConverter().getCertificate(certificateBuilder.build(contentSigner));

        SharedPreferences deviceKeyPref = c.getSharedPreferences(
                c.getString(R.string.device_key_and_cert), MODE_PRIVATE);
        deviceKeyPref.edit().putString(c.getString(R.string.certificate),
                Base64.encodeToString(certificate.getEncoded(), Base64.NO_WRAP)).apply();
        Log.d("TlsHelper", "Generated new certificate successfully");
    } catch (Exception e){
        Log.e("TlsHelper", "initialiseCertificate");
        Log.e("StackTrace", Log.getStackTraceString(e));
    }
}
 

public static X509Certificate generateSignedCertificate(X509Certificate caCertificate, PrivateKey caPrivateKey, PublicKey publicKey, String CN) 
		throws NoSuchAlgorithmException, OperatorCreationException, CertificateException, 
		KeyStoreException, UnrecoverableKeyException, IOException, 
		InvalidKeyException, NoSuchPaddingException, InvalidParameterSpecException, 
		InvalidKeySpecException, InvalidAlgorithmParameterException, IllegalBlockSizeException, 
		BadPaddingException {

	X500NameBuilder builder = new X500NameBuilder(BCStyle.INSTANCE);

	builder.addRDN(BCStyle.CN, CN);

	// We want this root certificate to be valid for one year
	Calendar calendar = Calendar.getInstance();
	calendar.add(Calendar.YEAR, 1);

	ContentSigner sigGen = new JcaContentSignerBuilder("SHA1WithRSAEncryption").setProvider(BC).build(caPrivateKey);
	X509v3CertificateBuilder certGen = new JcaX509v3CertificateBuilder(
			caCertificate, 
			new BigInteger(80, new Random()), 
			new Date(System.currentTimeMillis() - 50000),
			calendar.getTime(),
			new X500Principal(builder.build().getEncoded()),
			publicKey);

	// Those are the extensions needed for the certificate to be a leaf certificate that authenticates a SSL server
	certGen.addExtension(new ASN1ObjectIdentifier("2.5.29.15"), true, new X509KeyUsage(X509KeyUsage.keyEncipherment));
	certGen.addExtension(new ASN1ObjectIdentifier("2.5.29.37"), true, new DERSequence(KeyPurposeId.id_kp_serverAuth));

	X509CertificateHolder certificateHolder = certGen.build(sigGen);
	X509Certificate certificate = new JcaX509CertificateConverter().setProvider(BC).getCertificate(certificateHolder);

	return certificate;

}
 

public static X509Certificate generateRootCertificate(KeyPair keys, String CN) 
		throws NoSuchAlgorithmException, OperatorCreationException, CertificateException, 
		KeyStoreException, UnrecoverableKeyException, IOException, 
		InvalidKeyException, NoSuchPaddingException, InvalidParameterSpecException, 
		InvalidKeySpecException, InvalidAlgorithmParameterException, IllegalBlockSizeException, 
		BadPaddingException {

	X500NameBuilder builder = new X500NameBuilder(BCStyle.INSTANCE);

	builder.addRDN(BCStyle.CN, CN);

	// We want this root certificate to be valid for one year 
	Calendar calendar = Calendar.getInstance();
	calendar.add( Calendar.YEAR, 1 );

	ContentSigner sigGen = new JcaContentSignerBuilder("SHA1WithRSAEncryption").setProvider(BC).build(keys.getPrivate());
	X509v3CertificateBuilder certGen = new JcaX509v3CertificateBuilder(
			builder.build(), 
			new BigInteger(80, new Random()), 
			new Date(System.currentTimeMillis() - 50000),
			calendar.getTime(),
			builder.build(),
			keys.getPublic());

	// Those are the extensions needed for a CA certificate
	certGen.addExtension(new ASN1ObjectIdentifier("2.5.29.19"), true, new BasicConstraints(true));
	certGen.addExtension(new ASN1ObjectIdentifier("2.5.29.15"), true, new X509KeyUsage(X509KeyUsage.digitalSignature));
	certGen.addExtension(new ASN1ObjectIdentifier("2.5.29.37"), true, new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth));

	X509CertificateHolder certificateHolder = certGen.build(sigGen);

	X509Certificate certificate = new JcaX509CertificateConverter().setProvider(BC).getCertificate(certificateHolder);

	return certificate;

}
 

/**
 * @param certificate certificate
 * @return common name
 * @throws IllegalArgumentException if certificate is incorrect type
 */
@NonNull
public static String getCommonName(Certificate certificate) {
    assertX509Certificate(certificate);
    String result = null;
    try {
        X500Name x500name = new JcaX509CertificateHolder((X509Certificate) certificate).getSubject();
        RDN cn = x500name.getRDNs(BCStyle.CN)[0];
        result = IETFUtils.valueToString(cn.getFirst().getValue());
    } catch (CertificateEncodingException ignored) {
    }

    return (result == null) ? "" : result;
}
 

public void setCountry( String country) {
    put(BCStyle.C,country);
}
 

public void setState( String state) {
    put(BCStyle.ST,state);
}
 

public void setLocality( String locality) {
    put(BCStyle.L,locality);
}
 

public void setStreet( String street) {
    put( BCStyle.STREET, street);
}
 

public void setOrganization( String organization) {
    put(BCStyle.O,organization);
}
 

public void setOrganizationalUnit( String organizationalUnit) {
    put(BCStyle.OU,organizationalUnit);
}
 

public void setCommonName( String commonName) {
    put(BCStyle.CN,commonName);
}