string dir =  string.Format("{0:yyyy-MM-dd}", date) + "/";

            OssClient client = new OssClient(Endpoint, AccessKeyId, AccessKeySecret);

            DateTime ex = DateTime.Now.AddSeconds();

            PolicyConditions policyConds = new PolicyConditions();

            policyConds.AddConditionItem(PolicyConditions.CondContentLengthRange, 0L, 1048576000L);

            policyConds.AddConditionItem(MatchMode.StartWith, PolicyConditions.CondKey, dir);

            string postPolicy = client.GeneratePostPolicy(ex, policyConds);

            byte[] binaryData = Encoding.UTF8.GetBytes(postPolicy);

            string policy = Convert.ToBase64String(binaryData);

            var hmac = new HMACSHA1(Encoding.UTF8.GetBytes(AccessKeySecret));

            var hashBytes = hmac.ComputeHash(Encoding.UTF8.GetBytes(policy));

            var signature = Convert.ToBase64String(hashBytes);

            OSSSign sign = new OSSSign

            {

                OSSAccessKeyId = AccessKeyId,

                policy = policy,

                signature = signature,

                Host = "https://" + BucketName + "." + Endpoint,

                success_action_status = "",

                Filename = "${filename}",

                key = dir + "${filename}"

            };

            TimeSpan ts = ex.ToUniversalTime() - new DateTime(, , , , , , );

            sign.expire = Convert.ToInt64(ts.TotalSeconds).ToString();

            sign.callback = JsonConvert.SerializeObject(new

            {

                callbackUrl = CallbackUrl,

                callbackHost = CallbackHost,

                callbackBody = "filename=${object}&size=${size}&mimeType=${mimeType}&height=${imageInfo.height}&width=${imageInfo.width}",

                callbackBodyType = "application/x-www-form-urlencoded"

            });

            //sign.callback = Convert.ToBase64String(Encoding.UTF8.GetBytes(sign.callback));

            return sign;

 LogHelper.Warn("oss 回调" + DateTime.Now.ToLongTimeString());

            string autorizationInput = context.Request.Headers["Authorization"];

            string pubKeyInput = context.Request.Headers["x-oss-pub-key-url"];

            string bucket = context.Request.Headers["x-oss-bucket"];

            LogHelper.Warn(autorizationInput + "==" + pubKeyInput);

            byte[] pubKey = Convert.FromBase64String(pubKeyInput);

            string pubKeyAddr = Encoding.Default.GetString(pubKey);//公钥的url地址

            //x-oss-pub-key-url 头的值必须以 开始

            if (!pubKeyAddr.StartsWith("http://gosspublic.alicdn.com/") && !pubKeyAddr.StartsWith("https://gosspublic.alicdn.com/"))

            {

                return;

            }

            #region 签名校验没有实现。。。。。。

            //string publickey = executeGet(pubKeyAddr);//公钥

            //publickey = publickey.Replace("-----BEGIN PUBLIC KEY-----", "");

            //publickey = publickey.Replace("\n", "");

            //publickey = publickey.Replace("-----END PUBLIC KEY-----", "");

            //获取待签名字符串

            //string queryString = context.Request.Url.Query;

            //string uri = context.Request.Url.AbsolutePath;

            //string decodeUri = HttpContext.Current.Server.UrlDecode(uri);

            //string authStr = decodeUri;

            //if (string.IsNullOrEmpty(queryString))

            //{

            //authStr += "?" + queryString;

            //}

            //authStr += "bucket=" + bucket;

            //using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())

            //{

            //    byte[] binKey = Convert.FromBase64String(publickey); // Base64解码

            //    RSAParameters rsap = new RSAParameters();

            //    rsap.Modulus = binKey;

            //    rsap.Exponent = new byte[] { 1, 0, 1 };

            //    rsa.ImportParameters(rsap);

            //    MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();

            //    var data = rsa.SignData(Convert.FromBase64String(authStr), md5);

            //    var flag = rsa.VerifyData(data, md5, Convert.FromBase64String(autorizationInput));

            //    if (flag)

            //        LogHelper.Warn("success");

            //}

            #endregion

            string filename = context.Request.Params["filename"];

            string companyid = context.Request.Params["companyid"];

            string typeid = context.Request.Params["typeid"];

            string size = context.Request.Params["size"];

            string mimeType = context.Request.Params["mimeType"];

            string height = context.Request.Params["height"];

            string width = context.Request.Params["width"];

 context.Response.ContentType = "application/json";

            context.Response.StatusCode = ;

            context.Response.Write("{\"Status\":\"OK\"}");

            context.Response.End();

/// <summary>
/// 读取公钥
/// </summary>
/// <param name="url"></param>
/// <returns></returns>
public string executeGet(string url)
{
string responseStr;
Uri address = new Uri(url);
HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
request.Accept = "application/xml";
request.ContentType = "application/xml;charset=utf-8";
using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
{
StreamReader reader = new StreamReader(response.GetResponseStream());
responseStr = reader.ReadToEnd();
}

return responseStr;
}