Flickr authentication for Windows Store applications.

gistfile1.cs

private const string ConsumerKey = "";
private const string ConsumerSecret = "";
private const string Callback = "";
private const string RequestTokenUrl = "https://secure.flickr.com/services/oauth/request_token";
private const string AuthorizeUrl = "https://secure.flickr.com/services/oauth/authorize";
private const string AccessTokenUrl = "http://www.flickr.com/services/oauth/access_token";

private async void ButtonConnectOnClick(object sender, RoutedEventArgs e)
{
    string requestTokenParameters = "oauth_callback=" + Uri.EscapeDataString(Callback);
    requestTokenParameters += "&" + "oauth_consumer_key=" + ConsumerKey;
    requestTokenParameters += "&" + "oauth_nonce=" + new Random().Next(1000000000);
    requestTokenParameters += "&" + "oauth_signature_method=HMAC-SHA1";
    requestTokenParameters += "&" + "oauth_timestamp=" + GetTimeStamp();
    requestTokenParameters += "&" + "oauth_version=1.0";

    var signature = CreateSignature("GET&" + Uri.EscapeDataString(RequestTokenUrl) + "&" + Uri.EscapeDataString(requestTokenParameters), ConsumerSecret);

    string requestTokenUrl = RequestTokenUrl + "?" + requestTokenParameters + "&oauth_signature=" + Uri.EscapeDataString(signature);
    string getResponse = await new HttpClient().GetStringAsync(requestTokenUrl);

    if (getResponse != null)
    {
        foreach (string value in getResponse.Split('&'))
        {
            String[] splits = value.Split('=');
            switch (splits[0])
            {
                case "oauth_token":
                    _oauthToken = splits[1];
                    break;
                case "oauth_token_secret":
                    _oauthTokenSecret = splits[1];
                    break;
            }
        }

        if (_oauthToken != null)
        {
            string autorizeUrl = AuthorizeUrl + "?oauth_token=" + _oauthToken + "&perms=write";
            var requestUri = new Uri(autorizeUrl);
            var callbackUri = new Uri(Callback);

            WebAuthenticationResult webAuthenticationResult = await WebAuthenticationBroker.AuthenticateAsync(
                                                    WebAuthenticationOptions.None,
                                                    requestUri,
                                                    callbackUri);
            if (webAuthenticationResult.ResponseStatus == WebAuthenticationStatus.Success)
            {
                int index = webAuthenticationResult.ResponseData.IndexOf("verifier=", StringComparison.Ordinal) + 9;
                string verifier = webAuthenticationResult.ResponseData.Substring(index);

                string accessTokenParameters =
                    "oauth_consumer_key=" + ConsumerKey +
                    "&oauth_nonce=" + new Random().Next(1000000000) +
                    "&oauth_signature_method=HMAC-SHA1" +
                    "&oauth_timestamp=" + GetTimeStamp() +
                    "&oauth_token=" + _oauthToken +
                    "&oauth_verifier=" + verifier +
                    "&oauth_version=1.0";

                string accessTokenSignature = CreateSignature(
                    "GET&" + Uri.EscapeDataString(AccessTokenUrl) + "&" + Uri.EscapeDataString(accessTokenParameters),
                    ConsumerSecret, _oauthTokenSecret);

                string accessTokenUrl = AccessTokenUrl + "?" + accessTokenParameters + "&oauth_signature=" + Uri.EscapeDataString(accessTokenSignature);

                var response = await new HttpClient().GetStringAsync(accessTokenUrl);
                foreach (string value in response.Split('&'))
                {
                    String[] splits = value.Split('=');
                    switch (splits[0])
                    {
                        case "oauth_token":
                            _oauthToken = splits[1];
                            break;
                        case "oauth_token_secret":
                            _oauthTokenSecret = splits[1];
                            break;
                    }
                }
            }
            else
            {
                Debug.WriteLine(webAuthenticationResult.ResponseStatus);
                Debug.WriteLine(webAuthenticationResult.ResponseErrorDetail);
            }
        }
    }
}

private static string CreateSignature(string baseString, string consumerSecret, string oauthTokenSecret = "")
{
    IBuffer keyMaterial = CryptographicBuffer.ConvertStringToBinary(consumerSecret + "&" + oauthTokenSecret, BinaryStringEncoding.Utf8);
    MacAlgorithmProvider hmacSha1Provider = MacAlgorithmProvider.OpenAlgorithm("HMAC_SHA1");
    CryptographicKey macKey = hmacSha1Provider.CreateKey(keyMaterial);
    IBuffer dataToBeSigned = CryptographicBuffer.ConvertStringToBinary(baseString, BinaryStringEncoding.Utf8);
    IBuffer signatureBuffer = CryptographicEngine.Sign(macKey, dataToBeSigned);
    String signature = CryptographicBuffer.EncodeToBase64String(signatureBuffer);
    return signature;
}