Help restoring Ripple Trade wallet from 7 years in cold storage

[Deep]

Back in 2013 I participated in the World Community Grid project with an XRP reward.  When the WCG promotion ended I exported the wallet from Ripple Trade onto a usb drive and haven't touched it since then.  Apparently GateHub replaced Ripple Trade.  I setup an account on GateHub and then went to import my wallet but the wallet backup is a 496 byte encrypted file and the GateHub import wants a 29 character long key that starts with a "s".  What options do I have to decrypt the Ripple Trade wallet backup?