I have been struggling with an encrypted iPhone 4 backup for a few days now.
I have just been able to extract the data so I thought I would pass on what I did.
I used Access Data PRTK and a word list that I exported from the computer where I found the iPhone backup.
This found the password, which consisted of 6 lower case letters and one nunber, in less than an hour.
I then used iPhone Backup Extractor Pro software and all of the data was extracted.
I was able to extract over 16,000 SMS messages and all of the other data that is normally available (photos, videos, contacts, notes, calendars, call records. voicemails etc).
I have no involvement with the software providers Access Data or Reincubate.
Got this an a recent update from Elcomsoft
Not sure if it's backwards compatible though …
In fact, there are two ways for you to recover your deleted data from iPhone. First, you can use a third-party tool to directly scan and recover data from your iPhone. Second, if you've synced your iPhone with iTunes, you also can regain your deleted data by