Anyone who has seen the screen below would exactly know what I’m talking about. Like everyone, I googled for answers, and most suggestions were to reset the iPhone and load using a backup. Here is an alternative way of successfully retrieving the passcode without involving a reset.
First, make a backup of your iPhone or iPad using iTunes and make sure you backup locally, i.e. to the computer rather than to iCloud.
Read the last note to find out an alternative way of finding the file without installing the iPhone Backup Extractor
The next step is to download a free version of iPhone Backup Extractor from here. Open the application, go to the backup you just made. On the expert right-hand window, you would see a tab for Expert Mode. Click on the tab and navigate to Home -> Library -> Preferences -> com.apple.restictionspassword.plist and download the file.
Open the downloaded file, and you should see something similar to below
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd " >
<plist version="1.0">
<dict>
<key>RestrictionsPasswordKey</key>
<data> hbBIgZnr1tsmKwehaQIqN51aIAg= </data>
<key>RestrictionsPasswordSalt</key>
<data> T5gIMw== </data>
</dict>
</plist>
As you can see, the password isn’t stored in plain text anymore. It uses a hashing algorithm. As it’s a known algorithm and we are only dealing with a maximum of 9999 combinations, it’s easy to crack. I came across this nice page here just for it. Once you open the page, go down until you see 4 text boxes. Copy your RestrictionPasswordKey and RestrictionPasswordSalt from your extracted file and key that in and click “crack it” and wait until your passcode is revealed!
On the same page for cracking the code, they explain an alternative way without the need for iPhone Backup Extractor. I tried it and it works, i.e. search for a file named 398bc9c2aeeab4cb0c12ada0f52eea12cf14f40b and open in text editor, and it has the same content as com.apple.restictionspassword.plist