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How do I generate an assertion token for Sharepoint Access on behalf of another user in C#

I have a web application with a number of modules. One of the modules grabs a number of excel files from SharePoint directories, and then combines the data in them. So far, I have been just mapping the folders to OneDrive and accessing them that way. But this always uses my OneDrive credentials, which need to be refreshed from time to time. The right way to do this is to access them directly from Sharepoint on behalf of the user logged into my web application. I have the delegated API permission things set up in Azure, and I have the client ID and secret, etc.. I've been reading a number of articles on how to do this. All of them talk about how to get the token on behalf of someone else. These articles also talk about the assertion token needing to be passed in order to get the on behalf of token. However, they don't tell you how to get the assertion token in the first place. Here is the code I currently have:
'''var client = new RestClient("https://login.microsoftonline.com/XXXX/oauth2/v2.0/token");
var request = new RestRequest();
request.Method = Method.Post;
request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
request.AddParameter("client_id", "MYCLIENTID", ParameterType.GetOrPost);
request.AddParameter("client_secret", "MYSECRET", ParameterType.GetOrPost);
request.AddParameter("scope", "https://MYTenent.sharepoint.com/.default", ParameterType.GetOrPost);
request.AddParameter("grant_type", "urn:ietf:params:oauth:grant-type:jwt-bearer", ParameterType.GetOrPost);
request.AddParameter("requested_token_use", "on_behalf_of", ParameterType.GetOrPost);
RestResponse response = client.Execute(request);'''
The result of this is of course an error that the assertion was not supplied. I didn't supply any more code, because I can't even get passed this. The rest of my code takes the token and passes it to an auth provider, which is then used to instantiate the GraphServiceClient. Based on what I've read, that client is then used to get the lists, files, etc...
So, my question is, how do I get the assertion token in the first place? I'm hoping the code I have written so far is in the correct direction and all I'm missing is the assertion token.
UPDATE:
I've gotten one answer that really didn't help. I pretty much copied and pasted the code (replacing the clientID, etc..) and I received an error> I was going to copy and paste it from the solution comments provided in the answer, but I guess you can't do that while editing.
Someone also asked if I was able to get the auth code from the URL. The answer to that is no. We use 2 factor authentication, and I tried to manually look at the URLS as I was logging in, while using break points to slow things down a bit. And I did not see an auth code. I did put a break point directly after the line of code:
var info = await _signInManager.GetExternalLoginInfoAsync();
And when I look at the info variable, I can see 4 tokens. One of them is an access token and another is an ID token. The last one is an expiration date. I don't see an auth code, and from what I understand, by the time I see the access code, it's too late. The auth code was already used to get the access code.
UPDATE 2:
I know that OBO is not what I want. I also know that in order to use delegated permissions, I need to use the Auth Code flow and not client credentials. I can't seem to get the auth code from the users initial log in. And I don't know how to get it otherwise.
For those of you that might be thinking "Does he need to be spoon fed?", the answer is yes, I do. I need a simple code example that will get me the auth code, so I can use it in the rest of the code I already have. If anyone can paste that code into an answer and not provide a link, that would be great. I'm sorry, but the links I have been given, just go to microsoft learn sites that go through the explaination, but don't give any code samples.

The OBO flow is obviously not applicable in your context, and if you're going to get an access token on behalf of a logged in user, then you should focus on auth code flow or ROPC flow.
The corresponding C# code segment is:
using Microsoft.Graph;
using Azure.Identity;
var scopes = new[] { "https://{tenant-name}.sharepoint.com/.default" };
// Multi-tenant apps can use "common",
// single-tenant apps must use the tenant ID from the Azure portal
var tenantId = "tenant id";
// Values from app registration
var clientId = "client id";
var clientSecret = "client secret";
// For authorization code flow, the user signs into the Microsoft
// identity platform, and the browser is redirected back to your app
// with an authorization code in the query parameters
var authorizationCode = "authorization code ";
// using Azure.Identity;
var options = new TokenCredentialOptions
{
AuthorityHost = AzureAuthorityHosts.AzurePublicCloud
};
// https://learn.microsoft.com/dotnet/api/azure.identity.authorizationcodecredential
var authCodeCredential = new AuthorizationCodeCredential(
tenantId, clientId, clientSecret, authorizationCode, options);
var accessToken = await authCodeCredential.GetTokenAsync(new Azure.Core.TokenRequestContext(scopes) { });
Console.WriteLine(accessToken.Token);
//var graphClient = new GraphServiceClient(authCodeCredential, scopes);

How to fix issue calling Amazon SP-API, which always returns Unauthorized, even with valid Token and Signature

I went through the guide of for getting setup to call the new SP-API (https://github.com/amzn/selling-partner-api-docs/blob/main/guides/developer-guide/SellingPartnerApiDeveloperGuide.md), and during the process checked off all of the api areas to grant access to (i.e. Orders, Inventory, etc). I am using the C# library provided by Amazon (https://github.com/amzn/selling-partner-api-models/tree/main/clients/sellingpartner-api-aa-csharp). I successfully get an access token and successfully sign the request, but always get the following error:
Access to requested resource is denied. / Unauthorized, with no details.
I am trying to perform a simple get to the /orders/v0/orders endpoint. What am I doing wrong?
Below is my code:
private const string MARKETPLACE_ID = "ATVPDKIKX0DER";
var resource = $"/orders/v0/orders";
var client = new RestClient("https://sellingpartnerapi-na.amazon.com");
IRestRequest restRequest = new RestRequest(resource, Method.GET);
restRequest.AddParameter("MarketPlaceIds", MARKETPLACE_ID, ParameterType.QueryString);
restRequest.AddParameter("CreatedAfter", DateTime.UtcNow.AddDays(-5), ParameterType.QueryString);
var lwaAuthorizationCredentials = new LWAAuthorizationCredentials
{
ClientId = AMAZON_LWA_CLIENT_ID,
ClientSecret = AMAZON_LWA_CLIENT_SECRET,
RefreshToken = AMAZON_LWA_REFRESH_TOKEN,
Endpoint = new Uri("https://api.amazon.com/auth/o2/token")
};
restRequest = new LWAAuthorizationSigner(lwaAuthorizationCredentials).Sign(restRequest);
var awsAuthenticationCredentials = new AWSAuthenticationCredentials
{
AccessKeyId = AMAZON_ACCESS_KEY_ID,
SecretKey = AMAZON_ACCESS_SECRET,
Region = "us-east-1"
};
restRequest = new AWSSigV4Signer(awsAuthenticationCredentials).Sign(restRequest, client.BaseUrl.Host);
var response = client.Execute(restRequest);

If you followed the SP-API guide, then you created a Role (which is the IAM ARN your app is registered with) and a User which has permissions to assume that role to make API calls.
However, one thing the guide is not clear about is that you can't make API calls using that user's credentials directly. You must first call the STS API's AssumeRole method with your User's credentials (AMAZON_ACCESS_KEY_ID/AMAZON_ACCESS_SECRET), and it will return temporary credentials authorized against the Role. You use those temporary credentials when signing requests.
AssumeRole will also return a session token which you must include with your API calls in a header called X-Amz-Security-Token. For a brief description of X-Amz-Security-Token see https://docs.aws.amazon.com/STS/latest/APIReference/CommonParameters.html

You also get this error if your sp app is under review, drove me nuts!

If you using c# take look to
https://github.com/abuzuhri/Amazon-SP-API-CSharp
AmazonConnection amazonConnection = new AmazonConnection(new AmazonCredential()
{
AccessKey = "AKIAXXXXXXXXXXXXXXX",
SecretKey = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
RoleArn = "arn:aws:iam::XXXXXXXXXXXXX:role/XXXXXXXXXXXX",
ClientId = "amzn1.application-XXX-client.XXXXXXXXXXXXXXXXXXXXXXXXXXXX",
ClientSecret = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
RefreshToken= "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
});
var orders= amazonConnection.Orders.ListOrders();

In our situation, we had to explicitly add an IAM policy to the user we defined as making the API call. Please see the link below and confirm that the user you have calling the API has the policy assigned to them:
https://github.com/amzn/selling-partner-api-docs/blob/main/guides/developer-guide/SellingPartnerApiDeveloperGuide.md#step-3-create-an-iam-policy
Somehow we went through the step-by-step setup twice, and adding this explicit policy was missed. Initially I believe it was added 'inline' as instructed, but that does not seem to work.

I dont think is a duplicated question, buy the solution may apply: https://stackoverflow.com/a/66860192/1034622

Microsoft Graph The token contains no permissions, or permissions cannot be understood

I am working with Microsoft Graph and have created an app that reads mail from a specific user.
However, after getting an access token and trying to read the mailfolders, I receive a 401 Unauthorized answer. The detail message is:
The token contains no permissions, or permissions cannot be understood.
This seems a pretty clear message, but unfortunately I am unable to find a solution.
This is what I have done so far:
Registering the app on https://apps.dev.microsoft.com
Giving it
application permissions Mail.Read, Mail.ReadWrite
(https://learn.microsoft.com/en-us/graph/api/user-list-mailfolders?view=graph-rest-1.0)
Have gotten administrator consent.
The permissions are:
- Written the code below to acquire an access token:
// client_secret retrieved from secure storage (e.g. Key Vault)
string tenant_id = "xxxx.onmicrosoft.com";
ConfidentialClientApplication client = new ConfidentialClientApplication(
"..",
$"https://login.microsoftonline.com/{tenant_id}/",
"https://dummy.example.com", // Not used, can be any valid URI
new ClientCredential(".."),
null, // Not used for pure client credentials
new TokenCache());
string[] scopes = new string[] { "https://graph.microsoft.com/.default" };
AuthenticationResult result = client.AcquireTokenForClientAsync(scopes).Result;
string token = result.AccessToken;
So far so good. I do get a token.
Now I want to read the mail folders:
url = "https://graph.microsoft.com/v1.0/users/{username}/mailFolders";
handler = (HttpWebRequest)WebRequest.Create(url);
handler.Method = "GET";
handler.ContentType = "application/json";
handler.Headers.Add("Authorization", "Bearer " + token);
response = (HttpWebResponse)handler.GetResponse();
using (StreamReader sr = new StreamReader(response.GetResponseStream()))
{
returnValue = sr.ReadToEnd();
}
This time I receive a 401 message, with the details:
The token contains no permissions, or permissions cannot be understood.
I have searched the internet, but can’t find an answer to why my token has no permissions.
Thanks for your time!
update 1
If I use Graph Explorer to read the mailfolders, then it works fine. Furthermore: if I grap the token id from my browser en use it in my second piece of code, then I get a result as well. So, the problem is really the token I receive from the first step.

To ensure this works like you expect, you should explicitly state for which tenant you wish to obtain the access token. (In this tenant, the application should, of course, have already obtained admin consent.)
Instead of the "common" token endpoint, use a tenant-specific endpoint:
string url = "https://login.microsoftonline.com/{tenant-id}/oauth2/v2.0/token";
(Where {tenant-id} is either the tenant ID of the tenant (a Guid), or any verified domain name.)
I would also strongly recommend against building the token request on your own, as you show in your question. This may be useful for educational purposes, but will tend to be insecure and error-prone in the long run.
There are various libraries you can use for this instead. Below, an example using the Microsoft Authentication Library (MSAL) for .NET:
// client_secret retrieved from secure storage (e.g. Key Vault)
string tenant_id = "contoso.onmicrosoft.com";
ConfidentialClientApplication client = new ConfidentialClientApplication(
client_id,
$"https://login.microsoftonline.com/{tenant_id}/",
"https://dummy.example.com", // Not used, can be any valid URI
new ClientCredential(client_secret),
null, // Not used for pure client credentials
new TokenCache());
string[] scopes = new string[] { "https://graph.microsoft.com/.default" };
AuthenticationResult result = client.AcquireTokenForClientAsync(scopes).Result
string token = result.AccessToken;
// ... use token

Google Data API Authorization Redirect URI Mismatch

Background
I am wanting to write a small, personal web app in .NET Core 1.1 to interact with YouTube and make some things easier for me to do and I am following the tutorials/samples in Google's YouTube documentation. Sounds simple enough, right? ;)
Authenticating with Google's APIs seems impossible! I have done the following:
Created an account in the Google Developer Console
Created a new project in the Google Developer Console
Created a Web Application OAuth Client ID and added my Web App debug URI to the list of approved redirect URIs
Saved the json file provided after generating the OAuth Client ID to my system
In my application, my debug server url is set (and when my application launches in debug, it's using the url I set which is http://127.0.0.1:60077).
However, when I attempt to authenticate with Google's APIs, I recieve the following error:
That’s an error.
Error: redirect_uri_mismatch
The redirect URI in the request, http://127.0.0.1:63354/authorize/,
does not match the ones authorized for the OAuth client.
Problem
So now, for the problem. The only thing I can find when searching for a solution for this is people that say
just put the redirect URI in your approved redirect URIs
Unfortunately, the issue is that every single time my code attempts to authenticate with Google's APIs, the redirect URI it is using changes (the port changes even though I set a static port in the project's properties). I cannot seem to find a way to get it to use a static port. Any help or information would be awesome!
NOTE: Please don't say things like "why don't you just do it this other way that doesn't answer your question at all".
The code
client_id.json
{
"web": {
"client_id": "[MY_CLIENT_ID]",
"project_id": "[MY_PROJECT_ID]",
"auth_uri": "https://accounts.google.com/o/oauth2/auth",
"token_uri": "https://accounts.google.com/o/oauth2/token",
"auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
"client_secret": "[MY_CLIENT_SECRET]",
"redirect_uris": [
"http://127.0.0.1:60077/authorize/"
]
}
}
Method That Is Attempting to Use API
public async Task<IActionResult> Test()
{
string ClientIdPath = #"C:\Path\To\My\client_id.json";
UserCredential credential;
using (var stream = new FileStream(ClientIdPath, FileMode.Open, FileAccess.Read))
{
credential = await GoogleWebAuthorizationBroker.AuthorizeAsync(
GoogleClientSecrets.Load(stream).Secrets,
new[] { YouTubeService.Scope.YoutubeReadonly },
"user",
CancellationToken.None,
new FileDataStore(this.GetType().ToString())
);
}
var youtubeService = new YouTubeService(new BaseClientService.Initializer()
{
HttpClientInitializer = credential,
ApplicationName = this.GetType().ToString()
});
var channelsListRequest = youtubeService.Channels.List("contentDetails");
channelsListRequest.Mine = true;
// Retrieve the contentDetails part of the channel resource for the authenticated user's channel.
var channelsListResponse = await channelsListRequest.ExecuteAsync();
return Ok(channelsListResponse);
}
Project Properties

The Original Answer works, but it is NOT the best way to do this for an ASP.NET Web Application. See the update below for a better way to handle the flow for an ASP.NET Web Application.
Original Answer
So, I figured this out. The issue is that Google thinks of a web app as a JavaScript based web application and NOT a web app with server side processing. Thus, you CANNOT create a Web Application OAuth Client ID in the Google Developer Console for a server based web application.
The solution is to select the type Other when creating an OAuth Client ID in the Google Developer Console. This will have Google treat it as an installed application and NOT a JavaScript application, thus not requiring a redirect URI to handle the callback.
It's somewhat confusing as Google's documentation for .NET tells you to create a Web App OAuth Client ID.
Feb 16, 2018 Updated Better Answer:
I wanted to provide an update to this answer. Though, what I said above works, this is NOT the best way to implement the OAuth workflow for a ASP.NET solution. There is a better way which actually uses a proper OAuth 2.0 flow. Google's documentation is terrible in regards to this (especially for .NET), so I'll provide a simple implementation example here. The sample is using ASP.NET core, but it's easily adapted to the full .NET framework :)
Note: Google does have a Google.Apis.Auth.MVC package to help simplifiy this OAuth 2.0 flow, but unfortunately it's coupled to a specific MVC implementation and does not work for ASP.NET Core or Web API. So, I wouldn't use it. The example I'll be giving will work for ALL ASP.NET applications. This same code flow can be used for any of the Google APIs you've enabled as it's dependent on the scopes you are requesting.
Also, I am assuming you have your application set up in your Google Developer dashboard. That is to say that you have created an application, enabled the necessary YouTube APIs, created a Web Application Client, and set your allowed redirect urls properly.
The flow will work like this:
The user clicks a button (e.g. Add YouTube)
The View calls a method on the Controller to obtain an Authorization URL
On the controller method, we ask Google to give us an Authorization URL based on our client credentials (the ones created in the Google Developer Dashboard) and provide Google with a Redirect URL for our application (this Redirect URL must be in your list of accepted Redirect URLs for your Google Application)
Google gives us back an Authorization URL
We redirect the user to that Authorization URL
User grants our application access
Google gives our application back a special access code using the Redirect URL we provided Google on the request
We use that access code to get the Oauth tokens for the user
We save the Oauth tokens for the user
You need the following NuGet Packages
Google.Apis
Google.Apis.Auth
Google.Apis.Core
Google.apis.YouTube.v3
The Model
public class ExampleModel
{
public bool UserHasYoutubeToken { get; set; }
}
The Controller
public class ExampleController : Controller
{
// I'm assuming you have some sort of service that can read users from and update users to your database
private IUserService userService;
public ExampleController(IUserService userService)
{
this.userService = userService;
}
public async Task<IActionResult> Index()
{
var userId = // Get your user's ID however you get it
// I'm assuming you have some way of knowing if a user has an access token for YouTube or not
var userHasToken = this.userService.UserHasYoutubeToken(userId);
var model = new ExampleModel { UserHasYoutubeToken = userHasToken }
return View(model);
}
// This is a method we'll use to obtain the authorization code flow
private AuthorizationCodeFlow GetGoogleAuthorizationCodeFlow(params string[] scopes)
{
var clientIdPath = #"C:\Path\To\My\client_id.json";
using (var fileStream = new FileStream(clientIdPath, FileMode.Open, FileAccess.Read))
{
var clientSecrets = GoogleClientSecrets.Load(stream).Secrets;
var initializer = new GoogleAuthorizationCodeFlow.Initializer { ClientSecrets = clientSecrets, Scopes = scopes };
var googleAuthorizationCodeFlow = new GoogleAuthorizationCodeFlow(initializer);
return googleAuthorizationCodeFlow;
}
}
// This is a route that your View will call (we'll call it using JQuery)
[HttpPost]
public async Task<string> GetAuthorizationUrl()
{
// First, we need to build a redirect url that Google will use to redirect back to the application after the user grants access
var protocol = Request.IsHttps ? "https" : "http";
var redirectUrl = $"{protocol}://{Request.Host}/{Url.Action(nameof(this.GetYoutubeAuthenticationToken)).TrimStart('/')}";
// Next, let's define the scopes we'll be accessing. We are requesting YouTubeForceSsl so we can manage a user's YouTube account.
var scopes = new[] { YouTubeService.Scope.YoutubeForceSsl };
// Now, let's grab the AuthorizationCodeFlow that will generate a unique authorization URL to redirect our user to
var googleAuthorizationCodeFlow = this.GetGoogleAuthorizationCodeFlow(scopes);
var codeRequestUrl = googleAuthorizationCodeFlow.CreateAuthorizationCodeRequest(redirectUrl);
codeRequestUrl.ResponseType = "code";
// Build the url
var authorizationUrl = codeRequestUrl.Build();
// Give it back to our caller for the redirect
return authorizationUrl;
}
public async Task<IActionResult> GetYoutubeAuthenticationToken([FromQuery] string code)
{
if(string.IsNullOrEmpty(code))
{
/*
This means the user canceled and did not grant us access. In this case, there will be a query parameter
on the request URL called 'error' that will have the error message. You can handle this case however.
Here, we'll just not do anything, but you should write code to handle this case however your application
needs to.
*/
}
// The userId is the ID of the user as it relates to YOUR application (NOT their Youtube Id).
// This is the User ID that you assigned them whenever they signed up or however you uniquely identify people using your application
var userId = // Get your user's ID however you do (whether it's on a claim or you have it stored in session or somewhere else)
// We need to build the same redirect url again. Google uses this for validaiton I think...? Not sure what it's used for
// at this stage, I just know we need it :)
var protocol = Request.IsHttps ? "https" : "http";
var redirectUrl = $"{protocol}://{Request.Host}/{Url.Action(nameof(this.GetYoutubeAuthenticationToken)).TrimStart('/')}";
// Now, let's ask Youtube for our OAuth token that will let us do awesome things for the user
var scopes = new[] { YouTubeService.Scope.YoutubeForceSsl };
var googleAuthorizationCodeFlow = this.GetYoutubeAuthorizationCodeFlow(scopes);
var token = await googleAuthorizationCodeFlow.ExchangeCodeForTokenAsync(userId, code, redirectUrl, CancellationToken.None);
// Now, you need to store this token in rlation to your user. So, however you save your user data, just make sure you
// save the token for your user. This is the token you'll use to build up the UserCredentials needed to act on behalf
// of the user.
var tokenJson = JsonConvert.SerializeObject(token);
await this.userService.SaveUserToken(userId, tokenJson);
// Now that we've got access to the user's YouTube account, let's get back
// to our application :)
return RedirectToAction(nameof(this.Index));
}
}
The View
#using YourApplication.Controllers
#model YourApplication.Models.ExampleModel
<div>
#if(Model.UserHasYoutubeToken)
{
<p>YAY! We have access to your YouTube account!</p>
}
else
{
<button id="addYoutube">Add YouTube</button>
}
</div>
<script>
$(document).ready(function () {
var addYoutubeUrl = '#Url.Action(nameof(ExampleController.GetAuthorizationUrl))';
// When the user clicks the 'Add YouTube' button, we'll call the server
// to get the Authorization URL Google built for us, then redirect the
// user to it.
$('#addYoutube').click(function () {
$.post(addYoutubeUrl, function (result) {
if (result) {
window.location.href = result;
}
});
});
});
</script>

As referred here, you need to specify a fix port for the ASP.NET development server like How to fix a port number in asp.NET development server and add this url with the fix port to the allowed urls. Also as stated in this thread, when your browser redirects the user to Google's oAuth page, you should be passing as a parameter the redirect URI you want Google's server to return to with the token response.

I noticed that there is easy non-programmatic way around.
If you have typical monotlith application built in typical MS convention(so not compatible with 12factor and typical DDD) there is an option to tell your Proxy WWW server to rewrite all requests from HTTP to HTTPS so even if you have set up Web App on http://localhost:5000 and then added in Google API url like: http://your.domain.net/sigin-google, it will work perfectly and it is not that bas because it is much safer to set up main WWW to rewrite all to HTTPS.
It is not very good practice I guess however it makes sense and does the job.

I've struggled with this issue for hours in a .net Core application. What finally fixed it for me was, in the Google developers console, to create and use a credential for "Desktop app" instead of a "Web application".

Yeah!! Using credentials of desktop app instead of web app worked for me fine. It took me more than 2 days to figure out this problem. The main problem is that google auth library dose not adding or supporting http://localhost:8000 as redirect uri for web app creds but credentials of desktop app fixed that issue. Cause its supporting http://___ connection instead of https: connection for redirect uri

Get Facebook's Application Access Token

I have to use Facebook's notification for my web app.
Facebook Graph API requires the Application Access Token for this action.
Is there a way to get this token by code (C# SDK) or is this generated by Facebook a single time?
Is this token static (and secret) or with expire datetime?
For info: https://developers.facebook.com/tools/access_token/ - App Token, not User Token!
Thanks

The answer is the dynamic way by code:
var fb = new FacebookClient();
dynamic result = fb.Get( "oauth/access_token", new
{
client_id = <myAppID>,
client_secret = <mySecretID>,
grant_type = "client_credentials"
} );
var apptoken = result.access_token;
Or by the combination or appid|secretid

You can just use the concatenation of id and secret with a pipe symbol in the middle:
app_id|app_secret
This is actually how the PHP SDK creates the app access token internally, so there should be no question about the reliability of this method. (From other endpoints where you actively query for an app access token you might get another token that does not match this scheme though.)

you can investigate the getApplicationAccessToken method as in another c# sdk project from github
https://github.com/barans/FacebookCsharpSdk/blob/master/FacebookCSharpSDK/FacebookClient/FacebookClient.cs