.NET has native class in System.Security namespace, called: SecureString
Using of this class could be useful if we don’t want to send strings over our private/public network in plain text format. Of course, this is not a 100% secure solution. It can be decoded, but at least we’re not sending plain text passwords in our network.

If I need hash of a string (that cannot be decoded), I can use this simple snippet as can be seen as 3rd method.

I create a static class with static methods, so I can use it anywhere in my code easily.

static class _SecureString
    {
        public static SecureString ENCODING(string _string)
        {
            SecureString secure = new SecureString();
            foreach (char c in _string)
            {
                secure.AppendChar(c);
            }
            return secure;
        }
 
        public static string DECODING(SecureString _secureString)
        {
            IntPtr valuePtr = IntPtr.Zero;
            try
            {
                valuePtr = Marshal.SecureStringToGlobalAllocUnicode(_secureString);
                return Marshal.PtrToStringUni(valuePtr);
            }
            finally
            {
                Marshal.ZeroFreeGlobalAllocUnicode(valuePtr);
            }
        }
 
        public static string HASH_GENERATE(string _inputString)
        {
            byte[] data = Encoding.UTF8.GetBytes(_inputString);
            using (SHA512 shaM = new SHA512Managed())
            {
                return Convert.ToBase64String(shaM.ComputeHash(data));
            }
        }
    }

Using the HASH could be useful, when we store passwords in database and make all authentications from there. We generate the password hash from a simple string and store the hashed result string in the database. SHA512 is strong enough. Next time when a user wants to authenticate, we again generate a hash from his/her typed-in password and compare it to the stored one. In this case we are not sending and receiving any readable password text in the network. Fast and simple solution.