Given that your key has expired.
$ gpg --list-keys
$ gpg --edit-key KEYID
Use the expire command to set a new expire date:
# Create the appropriate directory structure on the TimeCapsule and mount the root folder ('Data' in this example) | |
# Backup path: /Volumes/Data/iOS/Backup/ | |
$ cp -r ~/Library/Application\ Support/MobileSync/Backup/ /Volumes/Data/iOS | |
$ cd ~/Library/Application\ Support/MobileSync/ | |
$ rm -r Backup/ | |
$ ln -s /Volumes/Data/iOS/Backup/ ~/Library/Application\ Support/MobileSync/ | |
# Open iTunes select your iPhone/iPad and click 'Back Up Now'-buttom |