From the Store description:
The only app that locks your ALL YOUR FILES and then "automagically" removes them from your gallery!
- Say no to importing a photo in a locker app and then manually delete it from the photos app. Welcome 9Zen Universal Locker !
- Lock photos, videos & other files from your photo gallery and SD card in 9Zen Universal Locker, which can only be accessed from the app.
- Keep your private memories "private" !
- Fake Pin – Use this to open a fake locker when someone pressures you to open the app!
- Flick/Swipe to view next photo the way it does in Photos app.
- Recover your files even if the app crashes and doesn't open.
- Folder Management.
- Simple and beautiful design
- Create unlimited folders and organize your files accordingly
- Easy-to-use PIN pad access
- Recover PIN in case you forget it via mail
- Lock photos and videos from your regular photo gallery or SD-card to the ultra-secure 9Zen Universal Locker
- Unlock any photos and videos in 9Zen Universal Locker to have them re-appear in your regular photo gallery
- Create, Delete, Unlock, Copy & Move multiple folders within your locker
- Full-screen viewing for photos and videos
- Share your photos and videos easily
Some screens of this in action on my IDOL 4 Pro:
The PIN screen - enter your 'fake PIN' to go to a secondary database, in which you can put something innocuous; the folder view once you're 'in'; and the secure notes easter egg feature, not mentioned in the app description. Secret thoughts, eh?!
It's worth noting that the application doesn't encrypt your media, it just hides it in a secret app-specific folder that Windows 10 Photos (of File Explorer) doesn't know about. So the police (or a fellow geek) could still find something incriminating if they went looking through your file system with a low level utility, I suspect.
You can grab 9Zen Universal Locker UWP in the Store here. It's ad supported, but you pay a couple of pounds to get rid of the ads, as you'd expect.