ajgvvYdf

1import javax.crypto.*;
2import java.security.*;
3
4public class Symmetric {
5	private static Cipher cipher;
6	private static KeyGenerator keyGen;
7	private static SecretKey secretKey;
8	
9	/**
10	 * Symmetric Constructor
11	 * @author Matt Moore
12	 * @throws NoSuchAlgorithmException
13	 * @throws NoSuchPaddingException
14	 */
15	public Symmetric() throws NoSuchAlgorithmException, NoSuchPaddingException {
16		cipher = Cipher.getInstance("AES/ECB/PKCS5Padding"); //transformation
17		keyGen = KeyGenerator.getInstance("AES"); //must match alg used in trasnformation
18		secretKey = keyGen.generateKey(); //secret key
19	}
20	
21	public static void main(String args[])
22	{
23		try {
24			
25			Asymmetric a = new Asymmetric();
26			PublicKey pkTest = a.getPublic();
27			
28			Symmetric s = new Symmetric();
29			System.out.println(sessionKey(pkTest));
30				
31			
32
33		} catch (InvalidKeyException e) {
34			// TODO Auto-generated catch block
35			e.printStackTrace();
36		} catch (IllegalBlockSizeException e) {
37			// TODO Auto-generated catch block
38			e.printStackTrace();
39		} catch (BadPaddingException e) {
40			// TODO Auto-generated catch block
41			e.printStackTrace();		
42		} catch (NoSuchAlgorithmException e) {
43			// TODO Auto-generated catch block
44			e.printStackTrace();
45		} catch (NoSuchPaddingException e) {
46			// TODO Auto-generated catch block
47			e.printStackTrace();
48		}
49	}
50	
51	
52	
53	/**
54	 * Encrypts the provided string (the given message)
55	 * @author Matt Moore
56	 * @param msg
57	 * @return byte[], cipherText - encrypted string (as an array of bytes)
58	 * @throws InvalidKeyException
59	 * @throws IllegalBlockSizeException
60	 * @throws BadPaddingException
61	 */
62	public byte[] encrypt(String msg) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
63		//initialize cipher object
64		cipher.init(Cipher.ENCRYPT_MODE, secretKey);
65		//convert string msg to array of bytes
66		byte[] plainText = msg.getBytes();
67		//call update repeatedly for a long msg
68		return cipher.doFinal(plainText);
69	}
70	
71	/**
72	 * @author Matt Moore
73	 * @param pubKey
74	 * @return byte array - an encrypted secret key, using the given public key
75	 * @throws InvalidKeyException 
76	 * @throws BadPaddingException 
77	 * @throws IllegalBlockSizeException 
78	 * @throws NoSuchAlgorithmException 
79	 * @throws NoSuchPaddingException 
80	 */
81	public static byte[] sessionKey(PublicKey pubKey) throws 
82	InvalidKeyException, IllegalBlockSizeException, BadPaddingException, NoSuchAlgorithmException, NoSuchPaddingException 
83	{ 
84        // Instantiate and Initialize RSA cipher
85        Cipher cipher = Cipher.getInstance("RSA");  
86        cipher.init(Cipher.ENCRYPT_MODE, pubKey);  
87       
88        //Encrypt & Return
89        return cipher.doFinal(secretKey.getEncoded());
90	}
91	
92	/**
93	 * Decrypts the provided byte array (the cipherText)
94	 * @author Matt Moore
95	 * @param cipherText
96	 * @return String - the plainText, cipherText decrypted
97	 * @throws InvalidKeyException
98	 * @throws IllegalBlockSizeException
99	 * @throws BadPaddingException
100	 */
101	public String decrypt(byte[] cipherText) throws InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
102		//initialize cipher object
103		cipher.init(Cipher.DECRYPT_MODE, secretKey); //same key, SYMMETRIC
104		byte[] plainText = cipher.doFinal(cipherText);
105		return new String(plainText);
106	}
107	
108}