import android.os.Bundle;
import android.util.Log;
import android.app.Activity;

public class MainActivity extends Activity {

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  DESUtil u = new DESUtil();
  String mi = u.getEnc("I love you");
  Log.i("加密后", mi);
  String ming = u.getDec(mi);
  Log.i("解密后", ming);
 }
}

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

import android.util.Base64;

/**
 * 使用DES加密和解密工具類
 *
 * @author Administrator
 *
 */
public class DESUtil {

 private Key key;// 密鑰的key值
 private byte[] DESkey;
 private byte[] DESIV = { 0x12, 0x34, 0x56, 0x78, (byte) 0x90, (byte) 0xAB,
   (byte) 0xCD, (byte) 0xEF };
 private AlgorithmParameterSpec iv = null;// 加密算法的參數接口

 public DESUtil() {
  try {
   this.DESkey = "abcdefghijk".getBytes("UTF-8");// 設置密鑰
   DESKeySpec keySpec = new DESKeySpec(DESkey);// 設置密鑰參數
   iv = new IvParameterSpec(DESIV);// 設置向量
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");// 獲得密鑰工廠
   key = keyFactory.generateSecret(keySpec);// 得到密鑰對象
  } catch (Exception e) {
   e.printStackTrace();
  }
 }

 /**
  * 加密String 明文輸入密文輸出
  *
  * @param inputString
  *            待加密的明文
  * @return 加密后的字符串
  */
 public String getEnc(String inputString) {
  byte[] byteMi = null;
  byte[] byteMing = null;
  String outputString = "";
  try {
   byteMing = inputString.getBytes("UTF-8");
   byteMi = this.getEncCode(byteMing);
   byte[] temp = Base64.encode(byteMi, Base64.DEFAULT);
   outputString = new String(temp);
  } catch (Exception e) {
  } finally {
   byteMing = null;
   byteMi = null;
  }
  return outputString;
 }

 /**
  * 解密String 以密文輸入明文輸出
  *
  * @param inputString
  *            需要解密的字符串
  * @return 解密后的字符串
  */
 public String getDec(String inputString) {
  byte[] byteMing = null;
  byte[] byteMi = null;
  String strMing = "";
  try {
   byteMi = Base64.decode(inputString.getBytes(), Base64.DEFAULT);
   byteMing = this.getDesCode(byteMi);
   strMing = new String(byteMing, "UTF8");
  } catch (Exception e) {
  } finally {
   byteMing = null;
   byteMi = null;
  }
  return strMing;
 }

 /**
  * 加密以byte[]明文輸入,byte[]密文輸出
  *
  * @param bt
  *            待加密的字節碼
  * @return 加密后的字節碼
  */
 private byte[] getEncCode(byte[] bt) {
  byte[] byteFina = null;
  Cipher cipher;
  try {
   // 得到Cipher實例
   cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(Cipher.ENCRYPT_MODE, key, iv);
   byteFina = cipher.doFinal(bt);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   cipher = null;
  }
  return byteFina;
 }

 /**
  * 解密以byte[]密文輸入,以byte[]明文輸出
  *
  * @param bt
  *            待解密的字節碼
  * @return 解密后的字節碼
  */
 private byte[] getDesCode(byte[] bt) {
  Cipher cipher;
  byte[] byteFina = null;
  try {
   // 得到Cipher實例
   cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
   cipher.init(Cipher.DECRYPT_MODE, key, iv);
   byteFina = cipher.doFinal(bt);
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   cipher = null;
  }
  return byteFina;
 }
}