Journal

JWT continued

Home, Groningen


Tuesday, May 12th 2020


10:05 AM

So recently I made my JWT service. It’s working and nice but I realised this is not “it”. When I started making the JWT service I didn’t really know what jwt was and how it worked. I had sufficient understanding of cryptography to know what hashes and signatures were and I also knew the difference between symmetric encryption and asymmetric encryption.

What I thought though, is that JWT uses one single authoritative server to check tokens. This way, every time someone wants to verify a JWT they would need to make another request to the authoritative server to verify the token. A much better solution to this problem is signing the token with an asymmetric key. That way you can distribute your public key to everyone that wants to verify tokens and sign the tokens themselves with your private key. This way JWTs can really replace or enhance things like Oauth that use third-party authentication providers.

What I realised then, is that my JWT service, which uses the HMAC algorithm to sign the tokens, isn’t that great to use as a microservice. A good way to improve it would be to have it use an asymmetric key so that other servers can verify the tokens without having to make that extra request.

For the goals that I had in mind though, which were to use it for a single application, the best way would probably be to keep the jwt parts and the rest of the server together, which allows it to use HMAC and gain the performance benefits that come with it.