Android AES加密算法及其实现

找到了AES加密算法。（当然还有MD5,BASE64什么的http://snowolf.iteye.com/blog/379860这篇文章列举了很多，但是基本都是j2se平台的，android平台不一定支持，但是AES算法Android是自带了包的，从官方的http://developer.android.com/reference/javax/crypto/Cipher.html可以看到。
）

 AES加密算法是什么？大家可以自己去google，专家级程序员写好包，工程人员会用就行了。

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：

package com.qq;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

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

public class SimpleCrypto extends Activity {
     public static String encrypt(String seed, String cleartext) throws Exception {
            byte[] rawKey = getRawKey(seed.getBytes());
            byte[] result = encrypt(rawKey, cleartext.getBytes());
            return toHex(result);
        }

        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");
            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;
        }

        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;
        }

        public static String toHex(String txt) {
            return toHex(txt.getBytes());
        }
        public static String fromHex(String hex) {
            return new String(toByte(hex));
        }

        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;
        }

        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 final static String HEX = "0123456789ABCDEF";
        private static void appendHex(StringBuffer sb, byte b) {
            sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
        }
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        String masterPassword = "a";
        String originalText = "0123456789";
        byte[] text = new byte[]{'0','1','2','3','4','5','6','7','8','9'};
        byte[] password = new byte[]{'a'};
        try {
            String encryptingCode = SimpleCrypto.encrypt(masterPassword,originalText);
//          System.out.println("加密结果为 " + encryptingCode);
            Log.i("加密结果为 ",encryptingCode);
            String decryptingCode = SimpleCrypto.decrypt(masterPassword, encryptingCode);
            System.out.println("解密结果为 " + decryptingCode);
            Log.i("解密结果",decryptingCode);
           } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
    }
    }
}

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