- Make it easier to rotate `SECRET_KEY` by documenting this usage
for both sensitivity and rotation process. (ARCHBOM-1676).
- Just use a hash of the secret rather than HMAC + MD5. We're not
authenticating a message, so HMAC isn't really needed -- it just needs
to be unique, deterministic, and irreversible. SHAKE allows generation
of an arbitrary length hash without needing to truncate.
Also, rename tracking session ID generator for clarity -- there's no
encryption happening here.
Add additional test for existing claim of uniqueness.
e0e03dec5f