Why is OAuth nonetheless exhausting in 2023?

2023-04-26 08:41:47

OAuth is an ordinary protocol. Proper? And there are consumer libraries for OAuth 2.0 available in basically every programming language you can imagine.

You would possibly conclude that, armed with a consumer library, you’ll be capable of implement OAuth for any API in about 10 minutes. Or not less than in an hour.

In case you handle, please electronic mail us — we’d prefer to deal with you to a scrumptious dinner and listen to how you probably did it.

OAuth in follow

We applied OAuth for the 50 hottest APIs, comparable to Google (Gmail, Calendar, Sheets and so forth.), HubSpot, Shopify, Salesforce, Stripe, Jira, Slack, Microsoft (Azure, Outlook, OneDrive), LinkedIn, Fb and other OAuth APIs.‍

Our conclusion: The actual-world OAuth expertise is similar to JavaScript browser APIs in 2008. There’s a common consensus on how issues ought to be finished, however in actuality each API has its personal interpretation of the usual, implementation quirks, and nonstandard behaviors and extensions. The outcome: footguns behind each nook.

If it weren’t so annoying, it might be fairly humorous. Let’s dive in!

Drawback 1: The OAuth normal is simply too huge and sophisticated

“This API additionally makes use of OAuth 2.0, and we already did that a couple of weeks in the past. I ought to be finished by tomorrow.”
– Well-known final phrases from the intern

OAuth is a really huge normal. The OAuth 2.0’s official site presently lists 17 totally different RFCs (paperwork defining an ordinary) that collectively outline how OAuth 2 works. They cowl every little thing from the OAuth framework and Bearer tokens to risk fashions and personal key JWTs.

“However,” I hear you say, “certainly not all of those RFCs are related for a easy third-party-access token authorization with an API?”
You’re proper. Let’s focus solely on the issues which might be prone to be related for the everyday API third-party-access use case:

OAuth normal: OAuth 2.0 is the default now, however OAuth 1.0a continues to be utilized by some (and a pair of.1 is across the nook). As soon as you realize which one your API makes use of, transfer on to:
Grant sort: Do you want `authorization_code`, `client_credentials`, or `device_code`? What do they do, and when do you have to use every of them? When doubtful, strive `authorization_code`.
Aspect observe: Refresh tokens are additionally a grant sort, however form of a particular one. How they work is standardized, however the way you ask for them within the first place just isn’t. Extra on that later.
Now that you just’re prepared on your requests, let’s have a look at the various (72, to be exact) official OAuth parameters with an outlined that means and conduct. Frequent examples are `immediate`, `scope`, `viewers`, `useful resource`, `assertion`, and `login_hint`. Nonetheless, in our expertise, most API suppliers appear to be as oblivious to this checklist as you in all probability had been till now, so don’t fret an excessive amount of about it.

In case you assume this nonetheless feels too sophisticated and like so much to study, we are inclined to agree with you.

Most groups constructing public APIs appear to agree as effectively. As an alternative of implementing a full OAuth 2.0 subset, they only implement the components of OAuth they assume they want for his or her API’s use case. This results in fairly lengthy pages in docs outlining how OAuth works for this specific API. However we’ve a tough time blaming them; they’ve solely one of the best intentions in thoughts for his or her DX. And if they honestly tried to implement the complete normal, you’d must learn a small e-book!

The Salesforce authorization_code OAuth move. What’s to not like a couple of clear visible for this straightforward 10-step course of?

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The difficulty is that everyone has a barely totally different thought of which subset of OAuth is related for them, so you find yourself with numerous totally different (sub-) implementations.

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Drawback 2: All people’s OAuth is totally different in refined methods

As each API implements a unique subset of OAuth, you shortly get right into a state of affairs the place you’re compelled to learn their lengthy pages of OAuth docs intimately:

Which parameters do they require within the authorize name?
- For Jira, the `viewers` parameter is vital (and should be set to a selected mounted worth). Google prefers to deal with this by way of totally different scopes however actually cares concerning the `immediate` parameter. In the meantime, any individual at Microsoft found the `response_mode` parameter and calls for that you just all the time set it to `question`.
- The Notion API takes a radical method and does away with the ever-present `scope` parameter. In actual fact, you gained’t even discover the phrase “scope” of their API docs. Notion calls them “capabilities,” and also you set them if you register the app. It took us 30 confused minutes to grasp what was happening. Why did they reinvent this wheel?
- It will get worse with `offline_access`: Most APIs lately expire entry tokens after a short time. To get a refresh token, you could request “offline_access,” which must be finished by way of a parameter, a scope, or one thing you set if you register your OAuth app. Ask your API or OAuth physician for particulars.
What do they wish to see within the token request name?
- Some APIs, like Fitbit, insist on getting information within the headers. Most really need it within the physique, encoded as `x-www-url-form-encoded`, aside from a couple of, comparable to Notion, which desire to get it as JSON.
- Some need you to authenticate this request with Primary auth. Many don’t trouble with that. However beware, they might change their thoughts tomorrow.
The place ought to I redirect my customers to authorize?
- Shopify and Zendesk have a mannequin by which each person will get a subdomain like {subdomain}.myshopify.com. And sure, that features the OAuth authorization web page, so that you’d higher construct dynamic URLs into your mannequin and frontend code.
- Zoho Books has totally different information facilities for his or her prospects in several areas. Hopefully, they bear in mind the place their information resides: To authorize your app, your U.S. prospects ought to go to https://accounts.zoho.com, Europeans can go to https://accounts.zoho.eu, and Indians are welcome at https://accounts.zoho.in. The checklist goes on.
However not less than I can decide my callback URL, no?

We might go on for a very long time, however we predict you in all probability get the purpose by now.

OAuth is simply too complicated; let’s make a less complicated model of OAuth that has every little thing we’d like! ©XKCD

Drawback 3: Many APIs add nonstandard extensions to OAuth

Regardless that the OAuth normal is huge, many APIs nonetheless appear to seek out gaps in it for options they want. A standard concern we see is that you just want some information along with the `access_token` to work with the API. Wouldn’t or not it’s neat if this extra information might be returned to you along with the access_token within the OAuth move?

We truly assume this can be a good thought — orr not less than it’s higher than forcing customers to do quirky further API requests afterward to fetch this info (taking a look at you, Jira). However it does imply extra nonstandard conduct that you just particularly must implement for each API.

Right here’s a small checklist of nonstandard extensions we’ve seen:

Quickbooks employs a `realmID`, which you could go in with each API request. The one time they inform you this `realmID` is as a further parameter within the OAuth callback. Higher retailer it someplace protected!
Braintree does the identical with a `companyID`
Salesforce makes use of a unique API base URL for every buyer; they name this the `instance_url`. Fortunately, they return the `instance_url` of the person along with the entry token within the token response, however you do must parse it out from there and retailer it.
Sadly, Salesforce additionally does much more annoying issues: Entry tokens expire after a preset time period, which may be custom-made by the person. High quality to this point, however for some purpose they don’t inform you within the token response when the entry token you simply acquired will expire (all people else does this). As an alternative, you could question a further token particulars endpoint to get the (present) expiration date of the token. Why, Salesforce, why?
Slack has two several types of scopes: scopes you maintain as a Slack bot and scopes that mean you can take motion on behalf of the person who licensed your app. Good, however as a substitute of simply including totally different scopes for every, they applied a separate `user_scopes` parameter that you could go within the authorization name. You’d higher concentrate on this, and good luck discovering assist for this in your OAuth library.

For the sake of brevity and ease, we’re skipping the various not-really-standard OAuth flows we’ve encountered.

Drawback 4: “invalid_request” — debugging OAuth flows is tough

Debugging distributed techniques is all the time exhausting. It’s more durable when the service you’re working with makes use of broad, generic error messages.

OAuth2 has standardized error messages, however they’re about as helpful in telling you what’s happening as the instance within the title above (which, by the best way, is among the really helpful error messages from the OAuth normal).

You can argue that OAuth is an ordinary and that there are docs for each API, so what’s there to debug?
Rather a lot. I can not inform you how usually the docs are flawed. Or lacking a element. Or haven’t been up to date for the most recent change. Otherwise you missed one thing if you first checked out them. 80% of the OAuth flows we implement have some drawback upon first implementation and require debugging.

How did Randall observe me whereas I used to be debugging OAuth flows? ©XKCD

Some flows additionally break for, what appear to be, random causes: LinkedIn OAuth, as an example, breaks in the event you go in PKCE parameters. The error you get? “consumer error – invalid OAuth request.” That’s … telling? It took us an hour to grasp that passing in (optionally available, normally disregarded) PKCE parameters is what breaks the move.

One other widespread mistake is sending scopes that don’t match those you preregistered with the app. (Preregister scopes? Sure, plenty of APIs lately demand that.) This usually leads to a generic error message about there being a difficulty with scopes. Duh.

Drawback 5: Cumbersome approvals to construct on high of APIs

The reality is, in the event you construct towards another system by utilizing their API, you’re in all probability within the weaker place. Your prospects are asking for the mixing as a result of they’re already utilizing the opposite system. Now you could make them glad.

To be honest, many APIs are liberal and supply simple self-service signup flows for builders to register their apps and begin utilizing OAuth. However a few of the hottest APIs on the market require evaluations earlier than your app turns into public and can be utilized by any of their customers. Once more, to be honest, most assessment processes are sane and may be accomplished in a couple of days. They’re in all probability a web achieve when it comes to safety and high quality for finish customers.

However some infamous examples can take months to finish, and a few even require you to enter into revenue-share agreements:

Google requires a “safety assessment” if you wish to entry scopes with extra delicate person information, comparable to electronic mail contents. We’ve heard these evaluations can take days or perhaps weeks to go and require a nontrivial quantity of labor in your facet.
Trying to combine with Rippling? Prepare for his or her 30-plus questions and safety preproduction screening. We hear entry takes months (if you’re accepted).
HubSpot, Notion, Atlassian, Shopify, and just about all people else who has an integrations market or app retailer requires a assessment to get listed there. Some evaluations are delicate, and a few ask you for demo logins, video walkthroughs, weblog posts (sure!), and extra. Nonetheless, itemizing on {the marketplace} or retailer is usually optionally available.
Ramp, Brex, Twitter, and a great variety of others don’t have a self-service signup move for builders and require that you just fill in kinds for handbook entry. Many are fast to course of requests, however we’re nonetheless ready to listen to again from some after weeks.
Xero is a very drastic instance of a monetized API: If you wish to exceed a restrict of 25 linked accounts, you need to become a Xero partner and checklist your app of their app retailer. They’ll then take (as of the time of this writing) a 15% income minimize from each lead generated from that retailer.

Drawback 6: OAuth safety is tough and a transferring goal

As assaults have been uncovered, and the obtainable net applied sciences have advanced, the OAuth normal has modified as effectively. In case you’re seeking to implement the present safety finest practices, the OAuth working group has a rather lengthy guide for you. And in the event you’re working with an API that’s nonetheless utilizing OAuth 1.0a at present, you notice that backwards compatibility is a unending battle.

Fortunately, safety is getting higher with each iteration, however it usually comes at the price of extra work for builders. The upcoming OAuth 2.1 normal will make some present finest practices obligatory and contains obligatory PKCE (at present solely a handful of APIs require this) and extra restrictions for refresh tokens.

A minimum of OAuth already implements a two-factor auth mannequin. ©XKCD

The largest change has in all probability been ushered in with expiring entry tokens and the rise of refresh tokens. On the floor, the method appears easy: Every time an entry token expires, refresh it with the refresh token and retailer the brand new entry token and refresh token.

In actuality, after we applied this we needed to think about:

Race circumstances: How can we make sure that no different requests run whereas we refresh the present entry token?
Some APIs additionally expire the refresh token in the event you don’t use it for a sure variety of days (or if the person has revoked the entry). Anticipate some refreshes to fail.
Some APIs concern you a brand new refresh token with each refresh request …
… however some additionally silently assume that you’ll hold the previous refresh token and carry on utilizing it.
Some APIs will inform you the entry token expiration time in absolute values. Others solely in relative “seconds from now.” And a few, like Salesforce, don’t disclose this type of info simply.

Final however not least: Some issues we haven’t talked about but

Sadly, we’ve solely simply scratched the floor of your OAuth implementation. Now that your OAuth move runs and also you get entry tokens, it’s time to consider:

securely retailer these entry tokens and refresh tokens. They’re like passwords to your customers’ accounts. However hashing just isn’t an choice; you want safe, reversible encryption.
Checking that the granted scopes match the requested scopes (some APIs permit customers to vary the scopes they grant within the authorize move).
Avoiding race circumstances when refreshing tokens.
Detecting entry tokens revoked by the person on the supplier facet.
Letting customers know that entry tokens have expired, to allow them to re-authorize your app if wanted.
revoke entry tokens you now not want (or that the person has requested you delete below GDPR).
Modifications in obtainable OAuth scopes, supplier bugs, lacking documentation, and so forth.

A greater approach?

In case you’ve learn this far, you could be pondering, “There should be a greater approach!”

We expect there’s, which is why we’re constructing Nango: An open-source, self-contained service that comes with prebuilt OAuth flows, safe token storage, and computerized token refreshes for more than 90 OAuth APIs.

In case you give it a strive, we’d love to listen to your suggestions. And if you wish to share your worst OAuth horror story with us, we’d love to listen to about it in our Slack community.

Thanks for studying and glad authorizing!

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