Question

I have a generated a private key using CertAndKeyGen class. Now I want to encrypt the private key with a password and use it as key while starting PostgreSQL server. Can some one please help me with java code to encrypt the private key, where googling dint help me out. Below is my code I use to generate Private Key.

    CertAndKeyGen keypair = new CertAndKeyGen("RSA", "SHA1WithRSA", null);
    PrivateKey privKey = keypair.getPrivateKey();

Any help or suggestion will be really appreciated.

Answer 1

public class KeyEncryptExample {

    public static void main(String[] args) {
        try {
            String key = "mariahussain"; // needs to be at least 8 characters for DES

            FileInputStream fis = new FileInputStream("C:/Users/hussain.a/Desktop/original.txt");
            FileOutputStream fos = new FileOutputStream("C:/Users/hussain.a/Desktop/encrypted.txt");
            encrypt(key, fis, fos);

            FileInputStream fis2 = new FileInputStream("C:/Users/hussain.a/Desktop/encrypted.txt");
            FileOutputStream fos2 = new FileOutputStream("C:/Users/hussain.a/Desktop/decrypted.txt");
            decrypt(key, fis2, fos2);
        } catch (Throwable e) {
            e.printStackTrace();
        }
    }

    public static void encrypt(String key, InputStream is, OutputStream os) throws Throwable {
        encryptOrDecrypt(key, Cipher.ENCRYPT_MODE, is, os);
    }

    public static void decrypt(String key, InputStream is, OutputStream os) throws Throwable {
        encryptOrDecrypt(key, Cipher.DECRYPT_MODE, is, os);
    }

    public static void encryptOrDecrypt(String key, int mode, InputStream is, OutputStream os) throws Throwable {

        DESKeySpec dks = new DESKeySpec(key.getBytes());
        SecretKeyFactory skf = SecretKeyFactory.getInstance("DES");
        SecretKey desKey = skf.generateSecret(dks);
        Cipher cipher = Cipher.getInstance("DES"); // DES/ECB/PKCS5Padding for SunJCE

        if (mode == Cipher.ENCRYPT_MODE) {
            cipher.init(Cipher.ENCRYPT_MODE, desKey);
            CipherInputStream cis = new CipherInputStream(is, cipher);
            doCopy(cis, os);
        } else if (mode == Cipher.DECRYPT_MODE) {
            cipher.init(Cipher.DECRYPT_MODE, desKey);
            CipherOutputStream cos = new CipherOutputStream(os, cipher);
            doCopy(is, cos);
        }
    }

    public static void doCopy(InputStream is, OutputStream os) throws IOException {
        byte[] bytes = new byte[64];
        int numBytes;
        while ((numBytes = is.read(bytes)) != -1) {
            os.write(bytes, 0, numBytes);
        }
        os.flush();
        os.close();
        is.close();
    }

}