C# HttpWebRequest Date Header Formatting

Question

I\'m making a HttpWebRequest to S3, and I\'m trying to set the Date header to something like this:

\"Mon, 16 Jul 2012 01:16:18 -0000\"

Answer 1

You should use "X-Amz-Date" header.

public void GetObject(string AccessKeyID, string SecretKey){           
        /*objectKey = folder/folder/filename.zzz*/
        var url = "http://somehost/bucket/objectkey"

        HttpWebRequest request = (HttpWebRequest) WebRequest.Create(url);
        /*Fiddler proxy*/
        /*request.Proxy = new WebProxy("http://127.0.0.1:8888");*/

        request.Headers.Add("X-Amz-Date",String.Format("{0:ffffd,' 'dd' 'MMM' 'yyyy' 'HH':'mm':'ss' 'K}", DateTime.Now));
        request.Headers.Add("Authorization", $"AWS {AccessKeyID}:{SignAuthorizationString(request, SecretKey)}");

        WebResponse response = request.GetResponse();
        }
private string SignAuthorizationString(HttpWebRequest request, string SecretKey){
        //TODO: DOCS - http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html

        string canonicalizedResource = request.RequestUri.PathAndQuery;
        string canonicalizedAmzHeaders  = ComposeSignatureAmzHeadersForSigning(request);
        string stringToSign = request.Method + "\n"
                              + request.Headers.Get("Content-MD5") + "\n"
                              + request.ContentType + "\n"
                              + request.Headers.Get("Date") + "\n" /*Here the date will be blank*/
                              + canonicalizedAmzHeaders + canonicalizedResource;

        return GetSignedMessage(SecretKey, stringToSign);
        }
 private string ComposeSignatureAmzHeadersForSigning(HttpWebRequest request){
        SortedDictionary headersDictionary = new SortedDictionary(StringComparer.OrdinalIgnoreCase);
        foreach (string _key in request.Headers.Keys)
        {
            key = _key.ToLower(); 
            if (key.StartsWith("x-amz"))
            {
                if ("x-amz-meta-reviewedby".Equals(key))
                {
                    if (headersDictionary.ContainsKey(key))
                        headersDictionary[key] = headersDictionary[key] + "," + request.Headers[key];
                    else
                        headersDictionary[key] = request.Headers[key];
                }
                else
                    headersDictionary[key] = request.Headers.Get(key);
            }
        }
        StringBuilder stringBuilder = new StringBuilder();
        foreach (var pair in headersDictionary)
        {
            stringBuilder.Append(pair.Key)
                .Append(":")
                .Append(pair.Value)
                .Append("\n");

        }
        return stringBuilder.ToString();
        }
private static string GetSignedMessage(string key, string message){
        var crypt = HMACSHA1.Create();
        crypt.Key = Encoding.ASCII.GetBytes(key);
        crypt.ComputeHash(Encoding.UTF8.GetBytes(message));

        return Convert.ToBase64String(crypt.Hash);
        }