SmallOauth 1

What is SmallOauth1?

A smalle, super easy to use OAuth 1.0a library with support for the full OAuth flow. Supports both .NET Framework and .NET Core (by using .NET Standard)!

Copied from TinyOAuth1

Why?

I had to make an API integration against a service provider that still used OAuth 1.0(a) for authorization. I didn't find very many good, easy to use, well documented and small OAuth 1.0a libraries for .NET so I created SmallOauth1 from TinyOAuth1.

Install

Install package from NuGet or Package Manager Console:

PM> Install-Package SmallOauth1

How does OAuth 1.0a work?

Here's a short explanation of how OAuth 1.0a works and a couple of links with great information.

A short explanation

OAuth is used to access protected resources, in most cases an API endpoint. The goal of the OAuth 1.0a authorization flow is to get hold of an access token and an access token secret. When we have these pieces of information we can generate an Authorization: OAuth ... header that gets included in every API call. When this header contains the correct information the service provider of the API will let our requests come through.

First time authorization (getting the access tokens)

Before starting the authorization flow you will have been given a consumer key and consumer secret from the service provider. You have also been given three different urls, the requst token url, the authorize token url and the access token url.

• You start by request a request token.
• A request token and request token secret are returned.
• Using the request token you generate an authorization url.
• You navigate to this url and enter any details, in many cases it's a simple confirm page. It may (or should in the case of 1.0a) also contain a verification code which you take note of.

  When completing this page your request token is basically authorized and can be used in the next step.

• By using your request token, request token secret and verification code you request an access token.
• An access token and access token secret are returned (!), you can now start making API calls, keep on reading.

Save tokens

Once we have gotten hold of the access token and access token secret we can start making API calls, but before doing this we want to do one more thing:

• Save the access token and access token secret somewhere (safe)

It's up to you to solve this part. The library has no opinion (or functionality) about how to do this.

We don't want the users to go through the authorization flow each time so by saving this information a returning user can get back to work right away since we can skip the whole "First time authorization" step.

Making API calls

To make API calls we must construct an Authorization: OAuth ... header and include it with every API call. This header has a timestamp and oauth_nonce part which means it changes slightly on every API call (for security reasons).

Here's an example header:

Authorization: OAuth realm="http://sp.example.com/",
               oauth_consumer_key="0685bd9184jfhq22",
               oauth_token="ad180jjd733klru7",
               oauth_signature_method="HMAC-SHA1",
               oauth_signature="wOJIO9A2W5mFwDgiDvZbTSMK%2FPY%3D",
               oauth_timestamp="137131200",
               oauth_nonce="4572616e48616d6d65724c61686176",
               oauth_version="1.0"

Once the correct header is included you API calls should hopefully come through! Keep reading for code samples.

The reference that was used when building this library:

• https://oauth.net/core/1.0a/

In the code comments have been added pointing to different chapters of this documentation.

More reading:

• https://oauth1.wp-api.org/docs/basics/Auth-Flow.html
• https://www.cubrid.org/blog/dancing-with-oauth-understanding-how-authorization-works
• http://oauthbible.com/

How do I use this library?

Here's a full sample that goes through the steps listed in the How does OAuth 1.0a work? chapter.

First time authorization (getting the access tokens)

Note that once you have saved your access token and access token secret you can skip this step and move directly to Making API calls.

// *** Check if we have saved tokens already, if not do the following: ***

// Set up the basic config parameters
var config = new SmallOauthConfig
{
    AccessTokenUrl = "https://api.provider.com/oauth/accessToken",
    AuthorizeTokenUrl = "https://api.provider.com/oauth/authorize",
    RequestTokenUrl = "https://api.provider.com/oauth/requestToken",
    ConsumerKey = "CONSUMER_KEY",
    ConsumerSecret = "CONSUMER_SECRET"
};

// Use the library
var smallOauth = new SmallOauth(config);

// Get the request token and request token secret
var requestTokenInfo = await smallOauth.GetRequestTokenAsync();

// Construct the authorization url
var authorizationUrl = smallOauth.GetAuthorizationUrl(requestTokenInfo.RequestToken);

// *** You will need to implement these methods yourself ***
await LaunchWebBrowserAsync(authorizationUrl); // Use Process.Start(authorizationUrl), LaunchUriAsync(new Uri(authorizationUrl)) etc...
var verificationCode = await InputVerificationCodeAsync(authorizationUrl);

// *** Important: Do not run this code before visiting and completing the authorization url ***
var accessTokenInfo = await smallOauth.GetAccessTokenAsync(requestTokenInfo.RequestToken, requestTokenInfo.RequestTokenSecret, verificationCode);

Save tokens

// Implement this any way you see fit but remember to keep these safe or anyone can make API calls on behalf of the user
SaveAccessTokens(accessTokenInfo);

Making API calls

To make API calls we need to create an Authorization: OAuth ... header and use it in every API call. There are two good ways of doing this that this library supports

• Use the included HttpClient message handler that automatically generates and inserts the header on each API call (recommended)
• Manually generate and insert the header for each request

Using the SmallOauthMessageHandler (recommended)

Will automatically generate and insert the header on each API call.

var httpClient = new HttpClient(new SmallOauthMessageHandler(config, accessTokenInfo.AccessToken, accessTokenInfo.AccessTokenSecret));

// Now we just use the HttpClient like normally
var resp = await httpClient.GetAsync("http://api.provider.com/something/resource?id=12345");
var respJson = await resp.Content.ReadAsStringAsync();

Manually generating and inserting header

var requestMsg = new HttpRequestMessage();
requestMsg.Method = new HttpMethod("GET");
requestMsg.RequestUri = new Uri("http://api.provider.com/something/resource?id=12345");
requestMsg.Headers.Authorization = smallOauth.GetAuthorizationHeader(accessTokenInfo.AccessToken, accessTokenInfo.AccessTokenSecret, requestMsg.RequestUri.AbsolutePath, HttpMethod.Get);
var resp = await httpClient.SendAsync(requestMsg);
var respJson = await resp.Content.ReadAsStringAsync();