by erikerikson | 2025-05-27 22:47:11+00:00
Re-reading the article, I'm confused about where I was coming from too. The article claims that it was last updated May 7th but the two Archive captures[0][1] seem to be broken for me ATM. The link to the blog source on GitHub[2] (linked from the page) just gave me a 404 and searching for the file didn't yield another location so I can't look for a commit timestamp or delta.

There is a bit of switching back and forth between speaking from an API provider and an API consumer standpoint and it is possible that in not reading sufficiently carefully I misunderstood. I was also previously oblivious to the context of the product they are marketing here that turns out to include API SDK generation (including a webhook acceptance sdk for validating requests? I don't know). The nuance that the implementer is an API provider providing both direct API access and a webhook delivery API could easily have caused me to misunderstand properly written words that flew over my head in the midst of getting bored with the content in my failure to understand it.

A great question from the article, in its current state[3], is asking: are API keys are secure enough for webhooks? In theory, you could validate a webhook request by confirming that the API key matches your in memory copy of that key. Either that or signature validation is usually supplied by the service SDK or example code that you cut and paste anyway.

Sadly, for a long time, it was too much to ask some clients to provide HTTPS security for connections and those requests had to be sent over HTTP, which would require alternative mechanisms of supplying non-repudiation (proof the content had not been altered in transit). This may be a forcing factor of the convention and thank you to Let's Encrypt and others for helping the industry shift (though I still find stragglers occasionally).

In the current environment of mostly ubiquitous HTTPS any non-secure URL configuration could be rejected by a webhook sender and an API key comparison could be authentication enough while retaining the sender controlled nature of the authentication. However, that newly assumes confidentiality of the API key by two parties which a webhook implementer may not be sufficiently competent to guarantee. This could leave a webhook implementer in the position of processing malicious requests without the valid sender having a mechanism for detecting the breach and exposing the sender of the webhook request to messy, relationship damaging, potentially legal, arguments about whether they leaked a key. The signing process retains private signing materials under the custody of the sender, simplifying the threat model and reducing its surface.

So, while you're right that (if we aren't talking about the webhook request implementer using webhook implementer authentication) the webhook consumer isn't providing their own authentication system, they are providing security for the authentication system in the case of API key use. Perhaps this is a version of Postel's law? Personally as a business generating SDKs for APIs I would be inclined to go the other way and encourage customers to generate SDKs with signing rather than encouraging webhooks without signing. Demand is what it is and so are clients so... I can't fault them either.

Thank you for helping me understand that I had missed context (or at least giving me an opportunity to respond to the latest version of the page, though my making an error seems more probable).

[0] https://web.archive.org/web/20250526130006/https://www.speak... [1] https://web.archive.org/web/20250526184520/https://www.speak... [2] https://www.speakeasy.com/_gh-redirect/src/content/blog/webh... [3] https://web.archive.org/web/20250527215821/https://www.speak...