【平台开发】-Android使用MD5加密算法加密密码
16lz
2021-01-23
很多的Android软件都需要用户登录登录功能，在开发的时候像这些密码都是保存在SharedPreferences中，这些密码保存在/data/data/包名/shared_prefs下，保存在一个XML文件中，如下：
可以用FileBrower查看
开始说道正题，Android MD5加密算法虽然现在有些人已经将其解开了，但是它的加密机制依然很强大，我想绝大对数还是不会解开的。MD5加密算法是单向加密，只能用你的密码才能解开，要不就是会解密算法，否则想都别想解开。为了防止这种情况的发生。还可以对加密过的密码进行再次加密。
下面是个小例子：
main.xml
<? xml version = "1.0" encoding = "utf-8" ?> < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:orientation = "vertical" android:layout_width = "fill_parent" android:layout_height = "fill_parent" > < EditText android:id = "@+id/username" android:layout_width = "fill_parent" android:layout_height = "wrap_content" android:layout_marginLeft = "10dp" android:layout_marginTop = "20dp" android:layout_marginRight = "10dp" android:hint = "帐号" /> < EditText android:id = "@+id/password" android:password = "true" android:layout_width = "fill_parent" android:layout_height = "wrap_content" android:layout_marginLeft = "10dp" android:layout_marginTop = "10dp" android:layout_marginRight = "10dp" android:hint = "密码" /> < Button android:id = "@+id/save" android:layout_width = "fill_parent" android:layout_height = "wrap_content" android:layout_marginLeft = "10dp" android:layout_marginTop = "10dp" android:layout_marginRight = "10dp" android:text = "保存" /> < Button android:id = "@+id/login" android:layout_width = "fill_parent" android:layout_height = "wrap_content" android:layout_marginLeft = "10dp" android:layout_marginTop = "10dp" android:layout_marginRight = "10dp" android:text = "登录" /> </ LinearLayout > login.xml
<? xml version = "1.0" encoding = "utf-8" ?> < LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android" android:layout_width = "match_parent" android:layout_height = "match_parent" android:orientation = "vertical" > < TextView android:layout_width = "fill_parent" android:layout_height = "wrap_content" android:text = "login successful!" /> </ LinearLayout > login.java
package com.loulijun.md5demo; import android.app.Activity; import android.os.Bundle; public class Login extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super .onCreate(savedInstanceState); setContentView(R.layout.login); } } MD5Demo.java
package com.loulijun.md5demo; import java.security.MessageDigest; import android.app.Activity; import android.content.Intent; import android.content.SharedPreferences; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.Toast; public class MD5Demo extends Activity { private EditText username, password; private Button savebtn, loginbtn; String user, pass; @Override public void onCreate(Bundle savedInstanceState) { super .onCreate(savedInstanceState); setContentView(R.layout.main); username = (EditText) findViewById(R.id.username); password = (EditText) findViewById(R.id.password); savebtn = (Button) findViewById(R.id.save); loginbtn = (Button) findViewById(R.id.login); savebtn.setOnClickListener( new Button.OnClickListener() { @Override public void onClick(View v) { SharedPreferences pre = getSharedPreferences( "loginvalue" , MODE_WORLD_WRITEABLE); pass = MD5(password.getText().toString()); user = username.getText().toString(); if (!pass.equals( "" ) && !user.equals( "" )) { pre.edit() .putString( "username" , username.getText().toString()) .putString( "password" , encryptmd5(pass)).commit(); Toast.makeText(getApplicationContext(), "保存成功!" , Toast.LENGTH_SHORT).show(); } else { Toast.makeText(getApplicationContext(), "密码不能为空！" , Toast.LENGTH_LONG).show(); } } }); loginbtn.setOnClickListener( new Button.OnClickListener() { @Override public void onClick(View v) { SharedPreferences sp = getSharedPreferences( "loginvalue" , MODE_WORLD_READABLE); String loginuser = sp.getString( "username" , null ); String loginpass = sp.getString( "password" , null ); user = username.getText().toString(); pass = password.getText().toString(); String passmd5 = MD5(pass); String encryptmd5 = encryptmd5(passmd5); System.out.println( "username=" + loginuser + "-------------password=" + loginpass); System.out.println( "user==" + user + "-------------encryptmd5==" + encryptmd5); if (!user.equals( "" ) && !pass.equals( "" )) { if (user.equals(loginuser) && encryptmd5.equals(loginpass)) { Intent intent = new Intent(); intent.setClass(MD5Demo. this , Login. class ); MD5Demo. this .startActivity(intent); finish(); } else { Toast.makeText(getApplicationContext(), "密码是错误的！" , Toast.LENGTH_LONG).show(); } } else { Toast.makeText(getApplicationContext(), "密码不能为空！" , Toast.LENGTH_LONG).show(); } } }); } // MD5加密，32位 public static String MD5(String str) { MessageDigest md5 = null ; try { md5 = MessageDigest.getInstance( "MD5" ); } catch (Exception e) { e.printStackTrace(); return "" ; } char [] charArray = str.toCharArray(); byte [] byteArray = new byte [charArray.length]; for ( int i = 0 ; i < charArray.length; i++) { byteArray[i] = ( byte ) charArray[i]; } byte [] md5Bytes = md5.digest(byteArray); StringBuffer hexValue = new StringBuffer(); for ( int i = 0 ; i < md5Bytes.length; i++) { int val = (( int ) md5Bytes[i]) & 0xff ; if (val < 16 ) { hexValue.append( "0" ); } hexValue.append(Integer.toHexString(val)); } return hexValue.toString(); } // 可逆的加密算法 public static String encryptmd5(String str) { char [] a = str.toCharArray(); for ( int i = 0 ; i < a.length; i++) { a[i] = ( char ) (a[i] ^ 'l' ); } String s = new String(a); return s; } } 加密密码程序很简单，下面是运行的效果：
