Visual Application Launcher

namespace VAL.Core
{
	using System; 
	using System.IO; 
	using System.Security.Cryptography;
    using System.Text;

    /// <summary>
    /// Simple class to help encrypt \ descript a string
    /// </summary>
    public class EncryptionHelper
    {
        private static byte[] _salt = Encoding.ASCII.GetBytes("o680074VALM7c5");

        /// <summary>
        /// Encrypt the given string using AES.  The string can be decrypted using 
        /// DecryptStringAES().  The sharedSecret parameters must match.
        /// </summary>
        /// <param name="plainText">The text to encrypt.</param>
        /// <param name="sharedSecret">A password used to generate a key for encryption.</param>
        public static string Encrypt(string plainText, string sharedSecret)
        {
            if (string.IsNullOrEmpty(sharedSecret))
                throw new ArgumentNullException("sharedSecret");

            string outStr = null;                       // Encrypted string to return
            RijndaelManaged aesAlg = null;              // RijndaelManaged object used to encrypt the data.

            try
            {
                var key = new Rfc2898DeriveBytes(sharedSecret, _salt);

                aesAlg = new RijndaelManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);

                var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
                using (var msEncrypt = new MemoryStream())
                {
                    using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (var swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(plainText);
                        }
                    }
                    outStr = Convert.ToBase64String(msEncrypt.ToArray());
                }
            }
            finally
            {
                if (aesAlg != null)
                    aesAlg.Clear();
            }
            return outStr;
        }

        /// <summary>
        /// Decrypt the given string.  Assumes the string was encrypted using 
        /// EncryptStringAES(), using an identical sharedSecret.
        /// </summary>
        /// <param name="cipherText">The text to decrypt.</param>
        /// <param name="sharedSecret">A password used to generate a key for decryption.</param>
        public static string Decrypt(string cipherText, string sharedSecret)
        {
            if (string.IsNullOrEmpty(sharedSecret))
                throw new ArgumentNullException("sharedSecret");

            RijndaelManaged aesAlg = null;
            string plaintext = null;

            try
            {
                var key = new Rfc2898DeriveBytes(sharedSecret, _salt);

                aesAlg = new RijndaelManaged();
                aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
                aesAlg.IV = key.GetBytes(aesAlg.BlockSize / 8);

                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);              
                byte[] bytes = Convert.FromBase64String(cipherText);
                
                using (var msDecrypt = new MemoryStream(bytes))
                {
                    using (var csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (var srDecrypt = new StreamReader(csDecrypt))
                        {
                            plaintext = srDecrypt.ReadToEnd();
                        }                            
                    }
                }
            }
            finally
            {
                if (aesAlg != null)
                    aesAlg.Clear();
            }

            return plaintext;
        }
    }
}