OpenSSLTest.java

// 
// Generate Certificates / Keys using following URL:
//  https://adangel.org/2016/08/29/openssl-rsa-java/
// NOTE: Code is compiled using IBM Java rather than Oracle

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

import org.apache.commons.io.FileUtils;

/**
 * OpenSSLTest.java
 * 
 * Authur: Furqan Baqai
 * Created On: Apr 3, 2018
 * Email: baqai.furqan@gmail.com
 *
 * CHANGE LOG
 * ----------------
 * [Apr 3, 2018:Muhammad] - Initial checkin
 */

/**
 * @author Muhammad
 *
 */
public class OpenSSLTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		try {
			// Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
			Cipher cipher = Cipher.getInstance("RSA/ECB/NoPadding");
			String clearText = "Sample plain text";
			
			PublicKey publicKey = OpenSSLTest.loadPublicKey();
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
			byte[] encrypted = cipher.doFinal(clearText.getBytes(StandardCharsets.UTF_8));
			System.out.println("Encrypted text: "+encrypted);
			
			PrivateKey privateKey = OpenSSLTest.loadPrivateKey();
			cipher.init(Cipher.DECRYPT_MODE,privateKey);
			byte[] decrypted = cipher.doFinal(encrypted);
			System.out.println("Decrypted output = "+ new String(decrypted,StandardCharsets.UTF_8));
			
		} catch (NoSuchAlgorithmException | NoSuchPaddingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (BadPaddingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}		
	}
	
	public static PublicKey loadPublicKey(){
		// TODO Auto-generated method stub
		System.out.println("Loading puublic keys for encryption");
		try {
			String publicKeyPEM = FileUtils.readFileToString(new File("./sslCerts/publickey.pem"),
					StandardCharsets.UTF_8);
			publicKeyPEM = publicKeyPEM
							.replace("-----BEGIN PUBLIC KEY-----", "")
							.replace("-----END PUBLIC KEY-----", "")
							.replaceAll("\\s", "");
			System.out.println("Key is \n"+publicKeyPEM);
			byte[] publickeyDER = Base64.getDecoder().decode(publicKeyPEM);
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			PublicKey publicKey = keyFactory.generatePublic(new X509EncodedKeySpec(publickeyDER));
			System.out.println("Key loaded sucesfully");
			return publicKey;
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (NoSuchAlgorithmException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (InvalidKeySpecException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return null;
	}
	
	public static PrivateKey loadPrivateKey() throws Exception {
	    String privateKeyPEM = FileUtils.readFileToString(new File("./sslCerts/privatekey-pkcs8.pem"), StandardCharsets.UTF_8);

	    // strip of header, footer, newlines, whitespaces
	    privateKeyPEM = privateKeyPEM
	            .replace("-----BEGIN PRIVATE KEY-----", "")
	            .replace("-----END PRIVATE KEY-----", "")
	            .replaceAll("\\s", "");
	    System.out.println("Private key:\n"+privateKeyPEM);
	    // decode to get the binary DER representation
	    byte[] privateKeyDER = Base64.getDecoder().decode(privateKeyPEM);
	    
	    KeyFactory keyFactory = KeyFactory.getInstance("RSA");
	    PrivateKey privateKey = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(privateKeyDER));
	    return privateKey;
	}

}