A middle ground there that would work for restore of particular files is to use ecryptfs/encfs without encrypting filenames. I think ecryptfs at least knows how to do this. Then you can download the file with the proper name, but the contents are encrypted and decrypt them locally.
You could probably also hack up something to figure out locally what encrypted filename corresponds to what regular filename and go fish for the encrypted filename in CrashPlan. It will probably be clunky though.
You could probably also hack up something to figure out locally what encrypted filename corresponds to what regular filename and go fish for the encrypted filename in CrashPlan. It will probably be clunky though.