/**
 * Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

import java.util.Arrays;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import javax.crypto.KeyGenerator;
import java.security.AlgorithmParameters;
import javax.crypto.SecretKey;
import javax.crypto.Cipher;
import static java.lang.System.out;
        
/**
 * Chech if the key wrapper works properly with GCM mode:
 *  - generate secret key
 *  - init Cipher with AES/GCM/NoPadding
 *  - using the wrapper method of Cipher do key wrapping
 *  - check if we can't wrap it again with the same key/IV (negative case) 
 *  - using the unwrap method of Cipher do key unwrapping
 *  - compare the original key with unwrapped one.
 * 
 * @author Alexander Fomin
 */
public class AEADKeyWrapperTest {
    public static final int PASSED = 0;
    public static final int FAILED = 1;
    public static final int ERROR = 2;
    
    static final String AES = "AES";
    static final String TRANSFORMATION = "AES/GCM/NoPadding";
    static final String PROVIDER = "SunJCE";
    static final int KEY_LENGTH = 128;
    
    private final SecretKey key1;
    private final SecretKey keyToWrap;
    private int status = PASSED;
  
    public static void main( String argv[] )
            throws NoSuchAlgorithmException, NoSuchProviderException
    {
        AEADKeyWrapperTest test = new AEADKeyWrapperTest();

        int status = test.execute(PROVIDER, TRANSFORMATION);

        if (status != PASSED) 
            System.exit(status);
    } 
     
    public AEADKeyWrapperTest() 
            throws NoSuchAlgorithmException, NoSuchProviderException
    {
        //init Secret Key
        KeyGenerator kg = KeyGenerator.getInstance(AES, PROVIDER);
        kg.init(KEY_LENGTH);        
        key1 = kg.generateKey();
        keyToWrap = kg.generateKey();        
    }
    
    public int execute(String provider, String algo){      
        try {      
            // Initialization
            Cipher cipher = Cipher.getInstance(algo);
            cipher.init( Cipher.WRAP_MODE, key1);
            AlgorithmParameters params = cipher.getParameters();

            //wrap the key
            byte[] keyWrapper=cipher.wrap(keyToWrap);
                    
            try{ //check if we can't wrap it again with the same key/IV
                keyWrapper=cipher.wrap(keyToWrap);
                out.println("FAILED: expected IllegalStateException hasn't "
                        + "been thrown ");
                this.status = FAILED;         
            }catch(IllegalStateException ise){}//ignore expected exception
            
            //unwrap the key
            cipher.init(Cipher.UNWRAP_MODE, key1, params);
            Key unwrappedKey = cipher.unwrap(keyWrapper, algo, Cipher.SECRET_KEY);
            
            //check if we can unwrap second time
            unwrappedKey=cipher.unwrap(keyWrapper, algo, Cipher.SECRET_KEY);

            // Comparison
            if (!Arrays.equals(keyToWrap.getEncoded(), unwrappedKey.getEncoded())){
                out.println("FAILED: original and unwrapped keys are not equal.");
                status = FAILED;
            }
        }catch (Exception ex){//do not expect any exceptions
            status = ERROR;
            ex.printStackTrace();
        }
        
        return status;
  }
}