I have an application that receives certain pseudo-random input values and computes their keyed hash using HMAC-SHA256. The hashing key itself is 256-bits long, generated at random by a CSRNG.
Which category does the hashing key fall under in NIST's 2016 Recommendations? Is it a "Symmetric Data Encryption Key"?
If it doesn't fall under any of those categories, is there a recommended cryptoperiod for it, or can I use it ad eternum?
(I suspect that this is an irrelevant detail, but the pseudo-random input values the application is processing are themselves HMACs of other input values. However, they are computed by a third party. So, since I do not know or have access to the hashing key they use, I'm treating them as "pseudo-random.")