@simonselmer One way to check if it secure or not is to login in your smartthing page https://graph.api.smartthings.com/login/auth go to my devices and click on your device. In the raw description, you’ll see a bunch of number. If you see 98 in cc: section, it means that it got pair into secure mode, if not, it means it was unsecure.
here’s a look of mine (unsecure one)
zw:L type:1001 mfr:0086 prod:0103 model:0060 ver:1.03 zwv:4.05 lib:03 cc:5E,25,26,33,70,27,32,81,85,59,72,86,7A,73 ccOut:5A,82 role:05 ff:8700 ui:870
You will get into secure mode if you quick tap twice (instead of once) when your pair it at first.The benefit of having secure is that z-wave traffic that goes bettween smartthing hub and your device will be encrypted, so no one should be able to see it (ie: neibours or something). Note that it only affect the link communication between the device and the hub.
Note that I had an issue (I’m not sure if it’s a hub bug or the device bug) where it would pair in secure mode but would only work in unsecure mode device handler. I had to unpair it and re-pair it and it work…
In an ideal world. you should not need to configure the device in secure or insecure, this was a work-around as I don’t know if there is way to detect it (through code). I asked the question in this topic: How to know if device secure inclusion as well as this one New Z-Wave Fingerprint Format but didn’t get any response (yet).