package javasecurity;
import java.security.*;
import javax.crypto.*;
public class PrivateExample
{
	public static void main(String[] args) throws Exception
	{
		// 檢查輸入?yún)?shù)，得到明文
		if (args.length != 1)
		{
			System.err.println("Usage: java PrivateExample text");
			System.exit(1);
		}
		byte[] plainText = args[0].getBytes("UTF8");
		// 得到DES私鑰
		System.out.println("\nStart generating DES key");
		KeyGenerator keyGen = KeyGenerator.getInstance("DES");
		keyGen.init(56);
		Key key = keyGen.generateKey();
		System.out.println("Finish generating DES key");
		// 得到DES cipher 對象，并打印出算法的提供者
		Cipher cipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
		System.out.println("\n" + cipher.getProvider().getInfo());
		// 使用密鑰對明文進(jìn)行加密
		System.out.println("\nStart encryption");
		cipher.init(Cipher.ENCRYPT_MODE, key);
		byte[] cipherText = cipher.doFinal(plainText);
		System.out.println("Finish encryption: ");
		System.out.println(new String(cipherText, "UTF8"));
		// 使用同一把密鑰對密文進(jìn)行解密
		System.out.println("\nStart decryption");
		cipher.init(Cipher.DECRYPT_MODE, key);
		byte[] newPlainText = cipher.doFinal(cipherText);
		System.out.println("Finish decryption: ");
		System.out.println(new String(newPlainText, "UTF8"));
	}
}