API problem

Hi Michael,

I am Gaurav from Slideshare. We received your code through the feedback mail you sent. The problem is in the SHA1 hash calculation you are doing. The method you are using does not result in a correct hash calculation.

Calculate SHA1 like it's done in this sample code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;
using System.Xml;
using System.Web;
using System.Security.Cryptography;

namespace ConsoleApplication1
{
class Program
{
public static string CalculateSHA1(string text, Encoding enc)
{
byte[] buffer = enc.GetBytes(text);
SHA1CryptoServiceProvider cryptoTransformSHA1 =
new SHA1CryptoServiceProvider();
string hash = BitConverter.ToString(
cryptoTransformSHA1.ComputeHash(buffer)).Replace("-", "").ToLower();

return hash;
}

public static void getapi(String api_key,String shared_secret,String tags)
{
string timestamp = Convert.ToInt32(Math.Floor((DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0)).TotalSeconds)).ToString();
Console.Write("Timestamp:" + timestamp + "\n");

string lcUrl = "http://www.slideshare.net/api/1/get_slideshow_by_tag?api_key=" + api_key + "&ts=" + timestamp + "&hash=" + CalculateSHA1(shared_secret + timestamp, Encoding.UTF8) + "&tag=" + tags;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(lcUrl);

request.Method = "GET";
HttpWebResponse loWebResponse = (HttpWebResponse)request.GetResponse();
Encoding enc = Encoding.GetEncoding(1252);
StreamReader loResponseStream = new StreamReader(loWebResponse.GetResponseStream(), enc);

string lcHtml = loResponseStream.ReadToEnd();
Console.Write(lcHtml);

loWebResponse.Close();
loResponseStream.Close();

}

static void Main(string[] args)
{
getapi("api_key","shared_secret","tag");
}
}
}

Hope this helps. Please feel free to write back to us incase of any more questions.