programming-examples/c-sharp/Strings/C# Program to Encrypt Decrypt using Rijndael Key.cs

/*
 * C# Program to Encrypt/Decrypt using Rijndael Key
 */
using System;
using System.IO;
using System.Security.Cryptography;
namespace RijndaelManage
{
class Rijndael
{
    public static void Main()
    {
        try
            {
                string original = "Data For Encryption!!!!!";
                using (RijndaelManaged myRijndael = new RijndaelManaged())
                {
                    myRijndael.GenerateKey();
                    myRijndael.GenerateIV();
                    byte[] encrypted = EncryptStringToBytes(original, myRijndael.Key, myRijndael.IV);
                    string aftdecryp = DecryptStringFromBytes(encrypted, myRijndael.Key, myRijndael.IV);
                    Console.WriteLine("Original:   {0}", original);
                    Console.WriteLine("After Decryption: {0}", aftdecryp);
                }
            }
        catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }
    }
    static byte[] EncryptStringToBytes(string plainText, byte[] Key, byte[] IV)
    {
        if (plainText == null || plainText.Length <= 0)
            throw new ArgumentNullException("plainText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");
        byte[] encrypted;
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;
            ICryptoTransform encryptor = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV);
            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        swEncrypt.Write(plainText);
                    }
                    encrypted = msEncrypt.ToArray();
                }
            }
        }
        return encrypted;
    }
    static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
    {
        if (cipherText == null || cipherText.Length <= 0)
            throw new ArgumentNullException("cipherText");
        if (Key == null || Key.Length <= 0)
            throw new ArgumentNullException("Key");
        if (IV == null || IV.Length <= 0)
            throw new ArgumentNullException("Key");
        string plaintext = null;
        using (RijndaelManaged rijAlg = new RijndaelManaged())
        {
            rijAlg.Key = Key;
            rijAlg.IV = IV;
            ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
            using (MemoryStream msDecrypt = new MemoryStream(cipherText))
            {
                using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    {
                        plaintext = srDecrypt.ReadToEnd();
                    }
                }
            }
        }
        return plaintext;
    }
}
}

/*
Original     : Data for Encryption!!!!!
After Decryption : Data for Encryption!!!!!