Android之"AES"加密解密

一、"AES" 维基解释：高级加密标准（英语：Advanced Encryption Standard，缩写：AES），在密码学中又称Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。经过五年的甄选流程，高级加密标准由美国国家标准与技术研究院（NIST）于2001年11月26日发布于FIPS PUB 197，并在2002年5月26日成为有效的标准。2006年，高级加密标准已然成为对称密钥加密中最流行的算法之一。

     这里只大概解释一下， 详情请自行百度或者谷歌。

二、用法（Android）：

     1、布局：一个简单的布局，只为了直观的查看加密和解密后结果，后面有图，代码省略

      2、加密代码：创建一个加密类Encrypt

package com.example.mi;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import javax.crypto.spec.SecretKeySpec;public class Encrypt {private final static String HEX = "0123456789ABCDEF";  public static String encrypt(String seed, String cleartext) throws Exception {              byte[] rawKey = getRawKey(seed.getBytes());              byte[] result = encrypt(rawKey, cleartext.getBytes());              return toHex(result);          }     private static byte[] getRawKey(byte[] seed) throws Exception {              KeyGenerator kgen = KeyGenerator.getInstance("AES");      //        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");   //这个地方会报错，见好多demo用的这个，所以提示一下        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");  //正确        sr.setSeed(seed);              kgen.init(128, sr); // 192 and 256 bits may not be available              SecretKey skey = kgen.generateKey();              byte[] raw = skey.getEncoded();              return raw;          }private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {              SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");              Cipher cipher = Cipher.getInstance("AES");              cipher.init(Cipher.ENCRYPT_MODE, skeySpec);              byte[] encrypted = cipher.doFinal(clear);              return encrypted;          }   public static String toHex(String txt) {              return toHex(txt.getBytes());          }   public static String toHex(byte[] buf) {              if (buf == null)                  return "";              StringBuffer result = new StringBuffer(2*buf.length);              for (int i = 0; i < buf.length; i++) {                  appendHex(result, buf[i]);              }              return result.toString();          } private static void appendHex(StringBuffer sb, byte b) {              sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));          }   }

       3、解密代码：同样是创建一个解密的类Decrypt

package com.example.mi;import java.security.SecureRandom;import javax.crypto.Cipher;import javax.crypto.KeyGenerator;import javax.crypto.SecretKey;import javax.crypto.spec.SecretKeySpec;public class Decrypt {public static String decrypt(String seed, String encrypted) throws Exception {              byte[] rawKey = getRawKey(seed.getBytes());              byte[] enc = toByte(encrypted);              byte[] result = decrypt(rawKey, enc);              return new String(result);          }  private static byte[] getRawKey(byte[] seed) throws Exception {              KeyGenerator kgen = KeyGenerator.getInstance("AES");      //        SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");           SecureRandom sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");          sr.setSeed(seed);              kgen.init(128, sr); // 192 and 256 bits may not be available              SecretKey skey = kgen.generateKey();              byte[] raw = skey.getEncoded();              return raw;          }public static byte[] toByte(String hexString) {              int len = hexString.length()/2;              byte[] result = new byte[len];              for (int i = 0; i < len; i++)                  result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();              return result;          } private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {              SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");              Cipher cipher = Cipher.getInstance("AES");              cipher.init(Cipher.DECRYPT_MODE, skeySpec);              byte[] decrypted = cipher.doFinal(encrypted);              return decrypted;          }  }

     4、最后就是主界面控制什么时候加密什么解密了

           

package com.example.mi;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;public class MainActivity extends Activity {private EditText inputEt;private TextView encryptTv;private TextView decryptTv;private Button encryptBtn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);inputEt = (EditText) findViewById(R.id.input_et);encryptTv = (TextView) findViewById(R.id.encrypt_tv);decryptTv = (TextView) findViewById(R.id.decrypt_tv);encryptBtn = (Button) findViewById(R.id.encrypt_btn);final String masterPassword = "a";//加密解密的key  encryptBtn.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stub        String originalText = inputEt.getText().toString();  //要加密字符串try {String encryptingCode = Encrypt.encrypt(masterPassword,originalText);Log.i("加密结果为 ",encryptingCode);              encryptTv.setText(encryptingCode);            String decryptingCode = Decrypt.decrypt(masterPassword, encryptTv.getText().toString());            Log.i("解密结果为",decryptingCode);              decryptTv.setText(decryptingCode);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}              }});        }}

三、运行结果