java实现的DES加密算法详解

Cipher cipher = Cipher.getInstance("DES");

DESKeySpec keySpec = new DESKeySpec(new byte[1,2,3,4,5,6,7,8]);

SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("EDS");
SecretKey key = keyFactory.generateSecret(keySpec);

cipher.init(Cipher.ENCRYPT_MODE,key);

bytep[] ret = cipher.doFinal(data);

/**
* DES加密算法
* @param mode   模式： 加密，解密
* @param data   需要加密的内容
* @param keyData 密钥 8个字节数组
* @return     将内容加密后的结果也是byte[]格式的
*/
public static byte[] des(int mode,byte[] data,byte[] keyData)
{
    byte[] ret = null;
    //加密的内容存在并且密钥存在且长度为8个字节
    if (data != null
        && data.length>0
        &&keyData!=null
        && keyData.length==8) {
      try {
        Cipher cipher = Cipher.getInstance("DES");
        DESKeySpec keySpec = new DESKeySpec(keyData);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey key = keyFactory.generateSecret(keySpec);
        cipher.init(mode, key);
        ret = cipher.doFinal(data);
      } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
      } catch (NoSuchPaddingException e) {
        e.printStackTrace();
      } catch (IllegalBlockSizeException e) {
        e.printStackTrace();
      } catch (BadPaddingException e) {
        e.printStackTrace();
      } catch (InvalidKeySpecException e) {
        e.printStackTrace();
      } catch (InvalidKeyException e) {
        e.printStackTrace();
      }
    }
    return ret;
}
//DES 加密
public static byte[] desEncrypt(byte[] data,byte[] keyData){
    return des(Cipher.ENCRYPT_MODE,data,keyData);
}
//DES 解密
public static byte[] desDecrypt(byte[] data,byte[] keyData){
    return des(Cipher.DECRYPT_MODE,data,keyData);
}

package com.xqx.encrypsthow;
import android.app.Activity;
import android.os.Bundle;
import android.util.Base64;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
import utils.EncryptUtil;
import javax.crypto.*;
import javax.crypto.spec.DESKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;
import java.util.Arrays;
/**
 * Created by Administrator on 2015/10/16.
 */
/**
 * 对称加密
 */
public class SythEncryptActivity extends Activity {
  private EditText txtContent;
  private EditText txtPassword;
  private EditText txtResult;
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sythencrypylayout);
    txtContent = (EditText) findViewById(R.id.txt_content);
    txtPassword = (EditText) findViewById(R.id.txt_password);
    txtResult = (EditText) findViewById(R.id.txt_result);
  }
  /**
   * DES加密,要求密码必须8个字节，64bit长度 byte[8]
   * @param view
   */
  public void btnDESEncrypt(View view) {
    //获取需要加密的内容
    String content = txtContent.getText().toString();
    //获取密钥
    String password = txtPassword.getText().toString();
    //注意，加密，解密，秘钥都需要是字节数组
    byte[] keyData = password.getBytes();
    //需要加密的内容
    byte[] contentData = content.getBytes();
    if(keyData.length == 8) {
      byte[] encryptedData = EncryptUtil.des(Cipher.ENCRYPT_MODE, contentData, keyData);
      //获取加密后的数据（记住是byte[]类型的），用Base64编码 成可见的字符串形式
      String s = Base64.encodeToString(encryptedData, Base64.NO_WRAP);
      //显示加密后的内容
      txtResult.setText(s);
    }
  }
  /**
   * DES的解密
   * @param view
   */
  public void btnDESDecrypt(View view) {
    String encryptedStr = txtResult.getText().toString();
    if(encryptedStr.length()>0){
      String password = txtPassword.getText().toString();
      //因为在加密方法中，使用Base64对加密的内容进行编码，要解密的时候需要Base64的解码
      byte[] encryptedData = Base64.decode(encryptedStr, Base64.NO_WRAP);
      byte[] keyData = password.getBytes();
      //DES 要求 8个字节
      if(keyData.length == 8){
        //形成原始数据
        byte[] decryptedData = EncryptUtil.des(Cipher.DECRYPT_MODE, encryptedData, keyData);
        txtResult.setText(new String(decryptedData));
      }
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:orientation="vertical"
       android:layout_width="match_parent"
       android:layout_height="match_parent">
  <EditText
      android:id="@+id/txt_content"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:hint="请输入内容"
      />
  <EditText
      android:id="@+id/txt_password"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:hint="DES密钥"
      android:text="12345678"
      android:inputType="textVisiblePassword"
      />
  <EditText
      android:id="@+id/txt_result"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      />
  <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="DES加密"
      android:onClick="btnDESEncrypt"
      />
  <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="DES解密"
      android:onClick="btnDESDecrypt"
      />
</LinearLayout>