Encrypt stored data in Android

public static byte[] encrypt() throws Exception {
        String seed = "SuperSecretPassword";
        String plaintext = "This is insecure data!";

        //API for generating symmetric cryptographic keys
        KeyGenerator keygen = KeyGenerator.getInstance("AES");

        //Returns a new instance of SecureRandom that utilizes the 
        //SHA1 algorithm.
        SecureRandom secrand = SecureRandom.getInstance("SHA1PRNG");

        //Reseeds this SecureRandom instance with the specified seed.
        secrand.setSeed(seed.getBytes());

        //Initializes this KeyGenerator instance for the specified 
        //key size (in bits) using the specified randomness source.
        keygen.init(128, secrand);
        //Generates a secret key.
        SecretKey seckey = keygen.generateKey();
        //Returns the encoded form of the key.
        byte[] rawKey = seckey.getEncoded();

        //Create a new SecretKeySpec for the key data and AES algorithm.
        SecretKeySpec skeySpec = new SecretKeySpec(rawKey, "AES");
        //Creates a new Cipher for the specified transformation. 
        //The installed providers are searched in order for an 
        //implementation of the specified transformation. 
        //The first found provider providing the transformation 
        //is used to create the cipher.
        Cipher cipher = Cipher.getInstance("AES");

        //Initializes this cipher instance with the specified key.
        //The cipher is initialized for the specified operational 
        //mode (one of: encryption, decryption, key wrapping or key unwrapping) 
        //depending on opmode.
        //If this cipher instance needs any algorithm parameters 
        //or random values that the specified key cannot provide, 
        //the underlying implementation of this cipher is supposed 
        //to generate the required parameters (using its provider or random values). 
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

        //Finishes a multi-part transformation (encryption or decryption).
        //Processes the bytes in input buffer, and any bytes that 
        //have been buffered in previous update calls.
        byte[] encrypted = cipher.doFinal(plaintext.getBytes());

        return encrypted;
    }

解密只需要该这一句

cipher.init(Cipher.DECRYPT_MODE, skeySpec);