DES類：

public class DESEncrypt {
	
	/** 加密工具 */
	private Cipher encryptCipher = null;

	/** 解密工具 */
	private Cipher decryptCipher = null;

        private void initialize_encryptKey(String keyValue) throws Exception{
	        Key key = getKey(keyValue.getBytes());
		encryptCipher = Cipher.getInstance("DES");
		encryptCipher.init(Cipher.ENCRYPT_MODE, key);
	}

	public void initalize_dencryptkey(String keyValue) throws Exception {
                Key key = getKey(keyValue.getBytes());
		decryptCipher = Cipher.getInstance("DES");
		decryptCipher.init(Cipher.DECRYPT_MODE, key);
	}

	/**
	 * 從指定字串生成金鑰，金鑰所需的位元組陣列長度為8位 不足8位時後面補0，超出8位只取前8位
	 * 
	 * @param arrBTmp
	 *            構成該字串的位元組陣列
	 * @return 生成的金鑰
	 * @throws java.lang.Exception
	 */
	private Key getKey(byte[] arrBTmp) throws Exception {
		// 建立一個空的8位位元組陣列（預設值為0）
		byte[] arrB = new byte[8];

		// 將原始位元組陣列轉換為8位
		for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
			arrB[i] = arrBTmp[i];
		}
		// 生成金鑰
		Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
		return key;
	}

	/**
	 * 加密位元組陣列
	 * 
	 * @param arrB
	 *            需加密的位元組陣列
	 * @return 加密後的位元組陣列
	 * @throws Exception
	 */
	public byte[] encrypt(byte[] arrB) throws Exception {
		return encryptCipher.doFinal(arrB);
	}

	/**
	 * 解密位元組陣列
	 * 
	 * @param arrB
	 *            需解密的位元組陣列
	 * @return 解密後的位元組陣列
	 * @throws Exception
	 */
	public byte[] decrypt(byte[] arrB) throws Exception {
		return decryptCipher.doFinal(arrB);
	}

	/**
	 * 檔案file進行加密並儲存目標檔案destFile中
	 * 
	 * @param file
	 *            要加密的檔案 如c:/test/srcFile.txt
	 * @param destFile
	 *            加密後存放的檔名 如c:/加密後文件.txt
	 */
	public void encrypt(String sourceFileName, String diminationFileName) throws Exception {
		InputStream is = new FileInputStream(sourceFileName);
		OutputStream out = new FileOutputStream(diminationFileName);
		CipherInputStream cis = new CipherInputStream(is, encryptCipher);
		byte[] buffer = new byte[1024];
		int r;
		while ((r = cis.read(buffer)) > 0) {
			out.write(buffer, 0, r);
		}
		cis.close();
		is.close();
		out.close();
	}

	/**
	 * 檔案採用DES演算法解密檔案
	 * 
	 * @param file
	 *            已加密的檔案 如c:/加密後文件.txt * @param destFile 解密後存放的檔名 如c:/
	 *            test/解密後文件.txt
	 */
	public void decrypt(String sourceFileName, String diminationFileName) throws Exception {
		InputStream is = new FileInputStream(sourceFileName);
		OutputStream out = new FileOutputStream(diminationFileName);
		CipherOutputStream cos = new CipherOutputStream(out, decryptCipher);
		byte[] buffer = new byte[1024];
		int r;
		while ((r = is.read(buffer)) >= 0) {
			cos.write(buffer, 0, r);
		}
		cos.close();
		out.close();
		is.close();
	}

}