Is iPhone backup encrypted and password is forgotten or lost? How to find out? Can I find it without any tool or software? Maybe you can. But if you want it to be easy, a tool is necessary, such as iTunes Password Genius used in this video. Get more information about it here: http://www.isunshare.com/itunes-password-genius.html
Step 1: Download and install it on your computer where iPhone local backup is saved.
There are two versions are available. Choose trial or full version according to iPhone backup forgotten password length and complexity. For example, if password is less than 3 characters, trial version is OK.
Step 2: Run iTunes Password Genius and import iPhone backup file.
Click "Open" button and choose local iTunes backup file in pop-up window. Click OK. Or click "Add File" to browse whether there is another iTunes backup file for iPhone. And open it in backup password recovery software.
Step 3: Password attack type settings and forgotten iPhone backup password recovery.
Choose one type from "Type of attack", and make detailed settings for it. And then click "Start" button. About few seconds or minutes later, you will get iPhone backup password.
So choose iTunes Password Genius appropriate version and make appropriate settings for password recovery, password will be found in short time with 100% gurantee.