View Keychain from encrypted IOS 8.2 backup?
I had the same problem and found a great article that helped me decrypt the keychain from my iOS 9 backup: Recovering Google Authenticator Keys from iOS Backups.

Here are the steps for El Capitan:


Install pip: sudo easy_install pip
Install m2crypto (see answer to Trouble installing m2crypto with pip on El Capitan)


First, install openssl and swig with Homebrew: brew install openssl swig
Then install m2crypto using pip:

env LDFLAGS="-L$(brew --prefix openssl)/lib" \
CFLAGS="-I$(brew --prefix openssl)/include" \
SWIG_FEATURES="-cpperraswarn -includeall -I$(brew --prefix openssl)/include" \
pip install --user m2crypto


Install some more Python packages: 

pip install --user construct progressbar pycrypto pyasn1

Download the iPhone Data Protection Tools
Extract your backup: python backup_tool.py PATH_TO_BACKUP
And finally, decrypt your keychain:

python keychain_tool.py -d "PATH_TO_extract/KeychainDomain/keychain-backup.plist" "PATH_TO_extract/Manifest.plist"