string key = "1234567891123456";
            string secret = @"This is a secret.";
 
            Console.WriteLine("basic:");
            EncryptString(key, secret);
            Console.ReadKey();
 
            Console.WriteLine("salt the secret:");
            // good when there are multiple machines but a dynamic global shared secret (for example, Profile Create Date or User ID)
            string secret2 = secret + " ###" + DateTime.Now.Millisecond;
            EncryptString(key, secret2);
 
            secret2 = secret + " ###" + DateTime.Now.Millisecond;
            EncryptString(key, secret2);
 
            Console.ReadKey();
 
            Console.WriteLine("salt the key:"); 
            // good when the same machine encrypts/decrepts
            string uniqueMachineIdentifier = MachineId.GetProcessorID();
            Console.WriteLine("MachineId: " + uniqueMachineIdentifier);
            EncryptString(key + uniqueMachineIdentifier, secret);
            Console.ReadKey();
 
            Console.WriteLine("SHA1 hash the passphrase with a salt:"); 
            // note: talk about why hashing is good
            SHA1 sha = new SHA1CryptoServiceProvider();
            // This is one implementation of the abstract class SHA1.
            string password = "this is my user password and/or userid";
            byte[] saltedKey = Encoding.Default.GetBytes(key + password);
 
            byte[] result = sha.ComputeHash(saltedKey);
            EncryptString(Convert.ToBase64String(result), secret);
            Console.ReadKey();