Best way to encrypt/decrypt querystring in .Net

Please find the best way to do Encryption/Decryption in .net. If you use standard way of accessing query string parameter values after encrypting or hashing you will get errors. Using following way, it will generate safe Encryption/Decryption in query string.

Encrypt :

    static string Encrypt(string originalString)
    {
        if (String.IsNullOrEmpty(originalString))
        {
            return string.Empty;
        }
        DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
        MemoryStream memoryStream = new MemoryStream();
        CryptoStream cryptoStream = new CryptoStream(memoryStream,
            cryptoProvider.CreateEncryptor(bytes, bytes), CryptoStreamMode.Write);
        StreamWriter writer = new StreamWriter(cryptoStream);
        writer.Write(originalString);
        writer.Flush();
        cryptoStream.FlushFinalBlock();
        writer.Flush();
        return Convert.ToBase64String(memoryStream.GetBuffer(), 0, (int)memoryStream.Length);
    }

string qs = "?uid=" + Encrypt("sample user id & key");

Decrypt :

    static string Decrypt(string cryptedString)
    {
        if (String.IsNullOrEmpty(cryptedString))
        {
            return string.Empty;
        }
        DESCryptoServiceProvider cryptoProvider = new DESCryptoServiceProvider();
        MemoryStream memoryStream = new MemoryStream(Convert.FromBase64String(cryptedString));
        CryptoStream cryptoStream = new CryptoStream(memoryStream,
            cryptoProvider.CreateDecryptor(bytes, bytes), CryptoStreamMode.Read);
        StreamReader reader = new StreamReader(cryptoStream);
        return reader.ReadToEnd();
    }

    private string GetRawUrlQueryString(string key)
    {
        string val = string.Empty;

        string url = HttpContext.Current.Request.RawUrl;

        int start = url.IndexOf("?");
        if (start >= 0)
        {
            string qs = url.Substring(start + 1);
            string[] parts = qs.Split('&');
            foreach (string part in parts)
            {
                if (part.Trim().StartsWith(key + "="))
                {
                    val = part.Trim().Replace(key + "=", "");
                    break;
                }
            }
        }
        return val;
    }

string receiveduid = GetRawUrlQueryString("uid");
string uid =  Decrypt(receivedui);

Important :

Do not use Request.QueryString["uid"] get the query string value as .net framework by default convert actual query string value with url encode. If so your decryption or base64 conversion will fail.