libcurlnet

public static class InstagramPrivateAPI
    {
        private class ReferenceString //потому что иначе строки передаются по значению
        {
            public string val = "";
        }
        private static string proxyPass = "";

        static InstagramPrivateAPI()
        {
            Curl.GlobalInit((int)CURLinitFlag.CURL_GLOBAL_ALL);
        }

        public static Random rand = new Random(DateTime.Now.Millisecond);

        public static CURLcode OnSSLContext(SSLContext ctx, Object extraData)
        {
            // To do anything useful with the SSLContext object, you'll need
            // to call the OpenSSL native methods on your own. So for this
            // demo, we just return what cURL is expecting.
            return CURLcode.CURLE_OK;
        }

        public static Int32 OnWriteData(Byte[] buf, Int32 size, Int32 nmemb,
             Object extraData)
        {
            //Console.Write(System.Text.Encoding.UTF8.GetString(buf));
            ((ReferenceString)extraData).val += System.Text.Encoding.UTF8.GetString(buf);
            return size * nmemb;
        }

        public static Int32 OnReadData(Byte[] buf, Int32 size, Int32 nmemb,
        Object extraData)
        {
            FileStream fs = (FileStream)extraData;
            return fs.Read(buf, 0, size * nmemb);
        }

        public static string SendRequest(string url, bool post, string post_data, string user_agent, bool cookies, string userid)
        {
            Easy.ReadFunction rf;
            FileStream fs;
            ReferenceString instagram_response = new ReferenceString();
            int d = 0;
            bool success = true;
            //Наша задача - попробовать сначала выполнить действие без авторизации, а если не получилось -
            //то его же, но уже после авторизации
            do
            {
                Easy easy = new Easy();
                Easy.WriteFunction wf = new Easy.WriteFunction(OnWriteData);
                easy.SetOpt(CURLoption.CURLOPT_URL, "https://i.instagram.com/api/v1/" + url);
                easy.SetOpt(CURLoption.CURLOPT_WRITEFUNCTION, wf);
                easy.SetOpt(CURLoption.CURLOPT_WRITEDATA, instagram_response);
                easy.SetOpt(CURLoption.CURLOPT_USERAGENT, user_agent);
                easy.SetOpt(CURLoption.CURLOPT_FOLLOWLOCATION, true);

                Easy.SSLContextFunction sf = new Easy.SSLContextFunction(OnSSLContext);
                easy.SetOpt(CURLoption.CURLOPT_SSL_CTX_FUNCTION, sf);
                easy.SetOpt(CURLoption.CURLOPT_CAINFO, "ca-bundle.crt");
                easy.SetOpt(CURLoption.CURLOPT_SSL_VERIFYPEER, false);

                if (post)
                {
                    easy.SetOpt(CURLoption.CURLOPT_POST, true);
                    easy.SetOpt(CURLoption.CURLOPT_POSTFIELDS, post_data);
                }

        //Для каждого аккаунта Instagram храним куки в отдельно файле
                if (cookies)
                {
                    easy.SetOpt(CURLoption.CURLOPT_COOKIEFILE, string.Format("cookies{0}.txt", userid));
                }
                else
                {
                    easy.SetOpt(CURLoption.CURLOPT_COOKIEJAR, string.Format("cookies{0}.txt", userid));
                }


                SeasideResearch.LibCurlNet.CURLcode response = easy.Perform();
                easy.GetInfo(CURLINFO.CURLINFO_HTTP_CONNECTCODE, ref d);
                easy.Cleanup();
                easy = null;
                // Curl.GlobalCleanup(); обойдемся без этого
            } while (!success);

            return instagram_response.val;
        }

        public static string GenerateGuid()
        {
            var rand = new System.Random();
            return string.Format("{0}{1}-{2}-{3}-{4}-{5}{6}{7}",
                   rand.Next(0, 65535).ToString("x4"),
                   rand.Next(0, 65535).ToString("x4"),
                  rand.Next(0, 65535).ToString("x4"),
                   rand.Next(16384, 20479).ToString("x4"),
                  rand.Next(32768, 49151).ToString("x4"),
                   rand.Next(0, 65535).ToString("x4"),
                   rand.Next(0, 65535).ToString("x4"),
                   rand.Next(0, 65535).ToString("x4"));
        }

        public static string GenerateUserAgent()
        {
            var resolutions = new string[] { "720x1280", "320x480", "480x800", "1024x768", "1280x720", "768x1024", "480x320" };
            var versions = new string[] { "GT-N7000", "SM-N9000", "GT-I9220", "GT-I9100" };
            var dpis = new string[] { "120", "160", "320", "240" };

            var ver = versions[new System.Random().Next(0, versions.Count() - 1)];
            var dpi = dpis[new System.Random().Next(0, dpis.Count() - 1)];
            var res = resolutions[new System.Random().Next(0, resolutions.Count() - 1)];

            return "Instagram 6.24.0" + " Android (" +
                new System.Random().Next(10, 11).ToString() + "/" +
                new System.Random().Next(1, 3).ToString() + "." +
                new System.Random().Next(3, 5).ToString() + "." + new System.Random().Next(0, 5).ToString() +
                "; " + dpi + "; " + res + "; samsung; " + ver + "; " + ver + "; smdkc210; en_US)";
        }
        public static string GenerateSignature(string data)
        {
            string secret = "25eace5393646842f0d0c3fb2ac7d3cfa15c052436ee86b5406a8433f54d24a5";
            var secretBytes = Encoding.UTF8.GetBytes(secret);
            var dataBytes = Encoding.UTF8.GetBytes(data);
            string signature = "";

            using (var hmac = new bouncy.System.Security.Cryptography.HMACSHA256(secretBytes))
            {
                var hash = hmac.ComputeHash(dataBytes);
                for (int i = 0; i < hash.Length; i++)
                {
                    signature += hash[i].ToString("x2");
                }
                //    signature = Convert.ToBase64String(hash);
            }
            return signature;
        }
        public static string datetimeToUnixEpoch(DateTime datetime)
        {
            DateTime sTime = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
            return ((int)(datetime - sTime).TotalSeconds).ToString();
        }

        public class InstaResponse
        {
            public string status;
            public string media_id;
        }


        public static bool login(string userid, string username, string password)
        {
            // Define the GuID
            string guid = GenerateGuid();

            // Define the user agent
            string agent = GenerateUserAgent();

            // Set the devide ID
            string device_id = "android-" + guid;

            /* LOG IN */
            // You must be logged in to the account that you wish to post a photo too
            // Set all of the parameters in the string, and then sign it with their API key using SHA-256
            string data = "{\"device_id\":\"" + device_id + "\",\"guid\":\"" + guid + "\",\"username\":\"" +
                         username + "\",\"password\":\"" + password + "\",\"Content-Type\":\"application/" +
                         "x-www-form-urlencoded; charset=UTF-8\"}";
            var sig = GenerateSignature(data);
            InstaResponse obj = null;
            data = "signed_body=" + sig + "." + System.Web.HttpUtility.UrlEncode(data) + "&ig_sig_key_version=6";
            string login = SendRequest("accounts/login/", true, data, agent, false, userid)[0];


            if (login.StartsWith("Sorry, an error occurred while processing this request."))
            {
                return false;
            }
            else
            {
                if (string.IsNullOrEmpty(login))
                {
                    return false;
                }
                else
                {
                    //  Decode the array that is returned
                    try
                    {
                        obj = Newtonsoft.Json.JsonConvert.DeserializeObject<InstaResponse>(login);
                        var status = obj.status;
                        if (status == "ok") return true;
                    }
                    catch
                    {
                    }
                }
            }
            return false;
        }
    }