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by methou
385 days ago
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JWTs are just too fat, and JS users often forgets encoding is not encryption. I've seen some news site trackers send JWT in url/header to some 3rd party tracker. Content is no surprise, my full name, and email address, violates its own privacy policy. Otherwise it's very open and handy, from inspecting a jwt token I can learn a lot about the architectural design of many sites. |
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Unfortunately, it seems like 99% of the industry decides which token to use based on Medium articles, LLM responses or how many unmaintained packages that implement this thing they can find on NPM.
JWT is mostly used as an access token, but for the vast majority of use cases it's a bad fit. If you've got low traffic no strict multi-region deployment requirements, random IDs are the best approach for you. They are extremely lean and easy to revoke. It's pretty secure: the only common vulnerabilities I can think of with this approach are session fixation[1] and timing attacks[2]. Both attacks are preventable if you take just a few simple precautions:
1. Always generate 32-byte session IDs using a cryptographically secure random number generator on authentication. (Never re-use existing session IDs for new logins)
2. Either use a cryptographic hash (e.g. SHA-256 or Blake2b) of the session ID a the database field used when querying sessions or make sure that the Session ID field is indexed with a hash-based index (B-trees are susceptible to timing attacks).
In cases where you really cannot use Session IDs, your service is usually big enough and important enough to use custom Protobuf tokens even a more special-purpose format like Macaroons. These formats give can be far more compact and give you full control on designing for your needs. For instance, if you want flexible claims (with most of them standardized across your services), together with encryption, you can use a combination of Protobuf and a libsodium secret box envelope.
[1] https://owasp.org/www-community/attacks/Session_fixation
[2] e.g. https://github.com/advisories/GHSA-cvw2-xj8r-mjf7