New kernel: HMAC errors

I’m writing a new kernel for Deno and I’ve got a MVP up and running on my machine (demo here). I think only one person has installed it so far and they’re getting HMAC errors when they receive the first “kernel_info_request” packet. I wrote a test that passes for him, so it’s not the HMAC algorithm that’s breaking. The only thing I can think of is somehow I’m hashing different data than the Jupyter frontend.

Is there any way to get the front end to print out the data that it is hashing and the hash result?