Passcode for App & Folder
Passcode Folder & Passcode Icon are outstanding Free Cydia Tweaks available from greensnow Cydia developer. This Tweak allows you to protect your Folder & Apps using a simple tap to enter Password procedure. after installing Icon Passcode, you have to set the master passcode by going to the Settings app (Settings -> Icon Passcode). You can then individually enable Passcode protection by tapping on the On/Off toggle (Settings -> Icon Passcode -> Locked Applications). This Tweak also allows to lock App switcher to ensure no one gets the access to the recent opened apps.
After installing both Icon Passcode & Folder Passcode, you will be prompted to set the master passcode via the Settings app (Settings -> Folder Passcode). or Passcode
To protect a folder, you need to tap and hold on the folder to put it in wiggle mode, then replace the title of the folder with “[lock]” and then tap “Done. You don’t need to worry about the title of the folder as it will revert back to the original title and also passcode protected the folder.
Both these Cydia Tweaks are Free to install obviously for Jailbroken iPhones.