Android AES加密算法及其实现

这个例子其实是来自http://www.tutorials-android.com/learn/How_to_encrypt_and_decrypt_strings.rhtml。

src目录主文件:

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  1. package com.qq;  
  2. import java.security.SecureRandom;  
  3.   
  4. import javax.crypto.Cipher;  
  5. import javax.crypto.KeyGenerator;  
  6. import javax.crypto.SecretKey;  
  7. import javax.crypto.spec.SecretKeySpec;  
  8.   
  9. import android.app.Activity;  
  10. import android.os.Bundle;  
  11. import android.util.Log;  
  12.   
  13. public class SimpleCrypto extends Activity {  
  14.      public static String encrypt(String seed, String cleartext) throws Exception {      
  15.             byte[] rawKey = getRawKey(seed.getBytes());      
  16.             byte[] result = encrypt(rawKey, cleartext.getBytes());      
  17.             return toHex(result);      
  18.         }      
  19.               
  20.         public static String decrypt(String seed, String encrypted) throws Exception {      
  21.             byte[] rawKey = getRawKey(seed.getBytes());      
  22.             byte[] enc = toByte(encrypted);      
  23.             byte[] result = decrypt(rawKey, enc);      
  24.             return new String(result);      
  25.         }      
  26.          
  27.         private static byte[] getRawKey(byte[] seed) throws Exception {      
  28.             KeyGenerator kgen = KeyGenerator.getInstance("AES");      
  29.             SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");      
  30.             sr.setSeed(seed);      
  31.             kgen.init(128, sr); // 192 and 256 bits may not be available      
  32.             SecretKey skey = kgen.generateKey();      
  33.             byte[] raw = skey.getEncoded();      
  34.             return raw;      
  35.         }      
  36.          
  37.               
  38.         private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {      
  39.             SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
  40.             Cipher cipher = Cipher.getInstance("AES");      
  41.             cipher.init(Cipher.ENCRYPT_MODE, skeySpec);      
  42.             byte[] encrypted = cipher.doFinal(clear);      
  43.             return encrypted;      
  44.         }      
  45.          
  46.         private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {      
  47.             SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");      
  48.             Cipher cipher = Cipher.getInstance("AES");      
  49.             cipher.init(Cipher.DECRYPT_MODE, skeySpec);      
  50.             byte[] decrypted = cipher.doFinal(encrypted);      
  51.             return decrypted;      
  52.         }      
  53.          
  54.         public static String toHex(String txt) {      
  55.             return toHex(txt.getBytes());      
  56.         }      
  57.         public static String fromHex(String hex) {      
  58.             return new String(toByte(hex));      
  59.         }      
  60.               
  61.         public static byte[] toByte(String hexString) {      
  62.             int len = hexString.length()/2;      
  63.             byte[] result = new byte[len];      
  64.             for (int i = 0; i < len; i++)      
  65.                 result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();      
  66.             return result;      
  67.         }      
  68.          
  69.         public static String toHex(byte[] buf) {      
  70.             if (buf == null)      
  71.                 return "";      
  72.             StringBuffer result = new StringBuffer(2*buf.length);      
  73.             for (int i = 0; i < buf.length; i++) {      
  74.                 appendHex(result, buf[i]);      
  75.             }      
  76.             return result.toString();      
  77.         }      
  78.         private final static String HEX = "0123456789ABCDEF";      
  79.         private static void appendHex(StringBuffer sb, byte b) {      
  80.             sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));      
  81.         }   
  82.     /** Called when the activity is first created. */  
  83.     @Override  
  84.     public void onCreate(Bundle savedInstanceState) {  
  85.         super.onCreate(savedInstanceState);  
  86.         setContentView(R.layout.main);  
  87.         String masterPassword = "a";  
  88.         String originalText = "0123456789";  
  89.         byte[] text = new byte[]{'0','1','2','3','4','5','6','7','8','9'};  
  90.         byte[] password = new byte[]{'a'};  
  91.         try {  
  92.             String encryptingCode = SimpleCrypto.encrypt(masterPassword,originalText);  
  93. //          System.out.println("加密结果为 " + encryptingCode);  
  94.             Log.i("加密结果为 ",encryptingCode);  
  95.             String decryptingCode = SimpleCrypto.decrypt(masterPassword, encryptingCode);  
  96.             System.out.println("解密结果为 " + decryptingCode);  
  97.             Log.i("解密结果",decryptingCode);  
  98.            } catch (Exception e) {  
  99.             // TODO Auto-generated catch block  
  100.             e.printStackTrace();  
  101.     }  
  102.     }  
  103. }  

布局文件main.xml和配置文件AndroidManifest.xml默认就好了。最后结果在Log里面看,利用adb logcat > d:\1.txt定位到D盘的1.txt文件,然后用记事本打开就,查找”加密结果为“就可以看到了:

运行结果(从log日志中看到的):

I/加密结果为 (  190): BFB77D8F1E1EE9D5E252926A12659DE8

I/解密结果(  190): 0123456789


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