For anybody who has forgotten your password for encrypted back up to restore.
My phone was replaced (A new phone) and I required to restore my latest back on itunes ,and was confronted with the issue of password.I tried many solutions and nothing worked.Then I found that I had a old back up which was not done by using encrypted back up.I restore this old back up to my phone and then I was allowed to change my encrypted back up password on itunes.I changed the password and then selected the encrypted back up (which was the latest) ,and when prompted for the password ,entered my newly created password. My encrypted back was restored to my phone without any issue.
So what you could allways follow as a guideline is to do a normal back up whenever you do an encrypted back up.
follow the link provided, this is how i got to know about it too.
sorry, the backup password cannot be reset unless you:
1. know the existing password. (which you dont in this case)
2. erase the iPhone's data completly as a new one.
this is because, the password is not stored anywhere online or is associated with your apple id.