You can easily passcode protect your iPhone by going to Settings > General > Passcode Lock. However, this only gives you the ability to set up a 4-digit code. If you’re a security freak and want to add an extra layer of protection to your iPhone, there is a simple hack that will let you create an alphanumeric password of as many characters as you want.
1. Download this file to your computer.
2. Email this file to an email account you have on your iPhone and open the attachment from there.
3. You should see the following screen:
4. Tap “Install”. You should get a warning message. Confirm by tapping “Install Now”.
5. It will then ask you to create a strong passcode of 1 or more characters. At this point, you can use letters and numbers to create a passcode as long as you want. Confirm your passcode.
6. You’re done. Now when you slide to unlock your iPhone, you will have to enter your alphanumeric passcode.
If you enter an incorrect password 18 times, it will wipe out your iPhone. To remove the data wiping feature, go to Settings > General > Profiles > Remove.
If you want to deactivate this alphanumeric passcode, go to Settings > General > Passcode Lock.
I think that’s a nice and simple hack for anyone looking to make his iPhone data a little safer.