using System;

using System.IO;

using System.Security.Cryptography;

namespace RijndaelManaged_Example

{

    class RijndaelExample

    {

        public static void Main()

        {

            try

            {

                string original = "Here is some data to encrypt!";

                // Create a new instance of the Rijndael

                // class.  This generates a new key and initialization

                // vector (IV).

                using (Rijndael myRijndael = Rijndael.Create())

                {

                    // Encrypt the string to an array of bytes.

                    byte[] encrypted = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV);

                    // Decrypt the bytes to a string.

                    string roundtrip = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV);

                    //Display the original data and the decrypted data.

                    Console.WriteLine("Original:   {0}", original);

                    Console.WriteLine("Round Trip: {0}", roundtrip);

                }

            }

            catch (Exception e)

            {

                Console.WriteLine("Error: {0}", e.Message);

            }

        }

        static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)

        {

            // Check arguments.

            if (plainText == null || plainText.Length <= )

                throw new ArgumentNullException("plainText");

            if (Key == null || Key.Length <= )

                throw new ArgumentNullException("Key");

            if (IV == null || IV.Length <= )

                throw new ArgumentNullException("Key");

            byte[] encrypted;

            // Create an Rijndael object

            // with the specified key and IV.

            using (Rijndael rijAlg = Rijndael.Create())

            {

                rijAlg.Key = Key;

                rijAlg.IV = IV;

                // Create a decrytor to perform the stream transform.

                ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);

                // Create the streams used for encryption.

                using (MemoryStream msEncrypt = new MemoryStream())

                {

                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))

                    {

                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))

                        {

                            //Write all data to the stream.

                            swEncrypt.Write(plainText);

                        }

                        encrypted = msEncrypt.ToArray();

                    }

                }

            }

            // Return the encrypted bytes from the memory stream.

            return encrypted;

        }

        static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)

        {

            // Check arguments.

            if (cipherText == null || cipherText.Length <= )

                throw new ArgumentNullException("cipherText");

            if (Key == null || Key.Length <= )

                throw new ArgumentNullException("Key");

            if (IV == null || IV.Length <= )

                throw new ArgumentNullException("Key");

            // Declare the string used to hold

            // the decrypted text.

            string plaintext = null;

            // Create an Rijndael object

            // with the specified key and IV.

            using (Rijndael rijAlg = Rijndael.Create())

            {

                rijAlg.Key = Key;

                rijAlg.IV = IV;

                // Create a decrytor to perform the stream transform.

                ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);

                // Create the streams used for decryption.

                using (MemoryStream msDecrypt = new MemoryStream(cipherText))

                {

                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))

                    {

                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))

                        {

                            // Read the decrypted bytes from the decrypting stream

                            // and place them in a string.

                            plaintext = srDecrypt.ReadToEnd();

                        }

                    }

                }

            }

            return plaintext;

        }

    }

}