Android通过AES128加密解密字符串

import java.security.SecureRandom;
 
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
 
/** download from http://www.open-open.com/code
 * Usage:
 * <pre>
 * String crypto = SimpleCrypto.encrypt(masterpassword,cleartext)
 * ...
 * String cleartext = SimpleCrypto.decrypt(masterpassword,crypto)
 * &lt;/pre&gt;
 * @author ferenc.hechler
 */
public class SimpleCrypto {
 
    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 &lt; 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 &lt; 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&gt;&gt;4)&amp;0x0f)).append(HEX.charAt(b&amp;0x0f));
    }
     
}