实现android的AES加密技术(2)

   
    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));