Not sure if this is germane or not. I just yesterday started to install openHAB and ran into the pairing issue.
Philips recently pushed out a new update which may have changed a new user registration method.
See Get Started - Philips Hue Developer Program
which notes:
“Currently it is possible to create your own usernames in the bridge (e.g. “newdeveloper”), however, this option will be removed in future bridge versions, so we need to use the randomly generated username that the bridge creates for you.”
Suspecting that the “secret word” used in the .cfg. file and the Hue username are supposed to match, and guessing that since the update that the Hue bridge has to issue the random username, I followed the example on the getting started page, creating a new user using the API tool. That issued a 20-digit or so user ID which I pasted back as the “secret word” in the config file.
And, it looks like that got things going. I had previously tried changing the “secret word” to something else, something longer than 10 characters, recommended elsewhere, but that didn’t work for me.