I just want to know if my code can be weak. Can anyone also spot a mistake in my code?Encryptpublic static String byte2hex(byte[] b) {    //we know exactly how long the resulting string should be so pass that information along to minimize allocations    StringBuilder hs = new StringBuilder(b.length*2);    for (int n = 0; n < b.length; n++) {        String stmp = Integer.toHexString(b[n] & 0xFF);        if (stmp.length() == 1)            hs.append(0).append(stmp);        else            hs.append(stmp);    }    return hs.toString().toUpperCase();}public static byte[] encryptMsg(String secretKeyString, String msgContentString)  {    try {        byte[] returnArray;        //generate AES secret key from users input        Key key = generateKey(secretKeyString);        //specify the cipher algorithm using AES        Cipher c = Cipher.getInstance(AES);        // specify the encryption mode        c.init(Cipher.ENCRYPT_MODE, key);        // encrypt        returnArray = c.doFinal(msgContentString.getBytes());        return returnArray;    }    catch (Exception e)    {        e.printStackTrace();        byte[] returnArray = null;        return returnArray;    }}private static Key generateKey(String secretKeyString) throws Exception {    // generate secret key from string    Key key = new SecretKeySpec(secretKeyString.getBytes(), AES);    return key;}Decryptpublic static byte[] hex2byte(byte[] b) {    if ((b.length % 2) != 0)        throw new IllegalArgumentException(hello);    byte[] b2 = new byte[b.length / 2];    for (int n = 0; n < b.length; n += 2) {        String item = new String(b, n, 2);        b2[n / 2] = (byte) Integer.parseInt(item, 16);    }    return b2;}public static byte[] decryptMsg(String secretKeyString, byte[] encryptedMsg)        throws Exception {    // generate AES secret key from the user input secret key    Key key = generateKey(secretKeyString);    // get the cipher algorithm for AES    Cipher c = Cipher.getInstance(AES);    // specify the decryption mode    c.init(Cipher.DECRYPT_MODE, key);    // decrypt the message    byte[] decValue = c.doFinal(encryptedMsg);    return decValue;}private static Key generateKey(String secretKeyString) throws Exception {    // generate AES secret key from a String    Key key = new SecretKeySpec(secretKeyString.getBytes(), AES);    return key;}
Encrypt and Decrypt
java;security;android;aes