recaptcha v2

ReCaptcha.cs

using System.Collections.Generic;
using System.Web;
using Newtonsoft.Json;

/// <summary>
/// Captcha helper
/// </summary>
/// <remarks>
/// Original http://stackoverflow.com/questions/27764692/validating-recaptcha-2-no-captcha-recaptcha-in-asp-nets-server-side
/// </remarks>
public class ReCaptcha
{

    public static ReCaptcha Validate(string encodedResponse)
    {
        var client = new System.Net.WebClient();

        const string privateKey = ".......";
        var userIp = HttpContext.Current.Request.UserHostAddress;

        var googleReply = client.DownloadString(string.Format("https://www.google.com/recaptcha/api/siteverify?secret={0}&response={1}", privateKey, encodedResponse));
        var captchaResponse = Newtonsoft.Json.JsonConvert.DeserializeObject<ReCaptcha>(googleReply);
        return captchaResponse;
    }

    [JsonProperty("success")]
    public bool Success { get; set; }

    /// <summary>
    /// The error code, if one has occured
    /// </summary>
    /// <returns>
    /// possible return values are found here: https://developers.google.com/recaptcha/docs/verify
    /// </returns>
    [JsonProperty("error-codes")]
    public List<string> ErrorCodes { get; set; }
}