What's the size of the credential public key?

[mikecmpbll]

We're using a varchar(255) column to store the credential public key (as you do in the rails example, too) and on the odd occasion we're seeing customers whose public key, on device registration, exceeds 256 bytes. I'm not sure what the cause for this is or why it's happening, and I can't find anything definitive on whether this is expected or erroneous.

Any ideas?

[santiagorodriguez96]

Hey @mikecmpbll!

Sorry for the late response!

Basically, the size of the public key is variable, depending on the algorithm that the client and authenticator use for creating the credential. You can actually specify which algorithms your server supports when configuring Webauthn.

I'm not sure why some of public keys created on your server are longer than 256 bytes, but maybe we could start by taking a look to your Webauthn configuration file and see which algorithms you are supporting? Maybe you are supporting one whose keys are longer than 256 bytes? 🤔