Stock Android isn't designed to give its user a full control under their files. Friends or family can relatively easy access personal videos, photos and other files without much effort. You can protect your device by adding a PIN, pattern, and so on, but still you can't be sure that your files are safe.

To strengthen your file protection, can add another layer of protection. This will make your device a bit safer for your personal stuff. XDA Forum Member aritraroy came up with an interesting idea and created an application to hide files by adding a PIN file. The app can hide the most popular file types like documents, images, apps, and ZIP archives from public view. The app has a built-in Stealth Mode that deceives intruders into a fake vault. When the users fails to log in three times, application blocks itself for 15 minutes.

Hidden files can be protected with 3-Layer Encryption Engine, so hidden files are extremely hard to crack. If this application is not something that you are looking for, be sure to unhide all files, otherwise you may lose them permanently.

Fight with your nosy friends and protect your files. Head over to the Androignito application thread and give it a try.

Please note: It is important to keep in mind that while applications like this are helpful to prevent casual snooping, it's almost guaranteed that an experienced hacker with device access will be able to have his way with your files. Furthermore, no details are given about the actual encryption algorithm used. But again, for preventing casual snooping, Androignito may be for you.