encrypted, or hashed?

> Shouldn't it read something like "encrypted with a secret key", rather 
> than "cryptographically hashed with a secret key"? I was thinking if it 
> was hashed, the kernel wouldn't be able to decode it when the ack comes 
> in.

No. It's using a hash algorithm with a key. Saying "encrypted with a secret key" would be
incorrect. Hash algorithms definitely != cipher algorithms.