Android實現AES加密/解密代碼

    import java.security.SecureRandom;


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

import android.app.Activity;  
import android.os.Bundle;  
import android.util.Log;  
import android.view.Menu;  
import android.view.MenuItem;  

public class MainActivity extends Activity {  

    private static final String TAG = "MainActivity";  

    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", "Crypto");  
        sr.setSeed(seed);  
        kgen.init(128, sr);   
        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, new IvParameterSpec(  
                new byte[cipher.getBlockSize()]));  
        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, new IvParameterSpec(  
                new byte[cipher.getBlockSize()]));  
        byte[] decrypted = cipher.doFinal(encrypted);  
        return decrypted;  
    }  

    private static String toHex(String txt) {  
        return toHex(txt.getBytes());  
    }  

    private static String fromHex(String hex) {  
        return new String(toByte(hex));  
    }  

    private 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 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));  
    }  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  

        String masterPassword = "key";  
        String originalText = "0123456789";  
        try {  
            String encryptingCode = MainActivity.encrypt(masterPassword,  
                    originalText);  

            Log.e(TAG, "加密后: " + encryptingCode);  
            String decryptingCode = MainActivity.decrypt(masterPassword,  
                    encryptingCode);  

            Log.e(TAG, "解密后: " + decryptingCode);  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  

    }  

}  </pre><br />