Default [Q] Device encryption and TWRP recovery?

I've enabled device encryption in the stock AT&T ROM. Is it possible to mount this encrypted /data in TWRP? The TWRP threads suggest it is, but TWRP 2.7.0.2 just errors out, never asking me for a password. The TWRP 2.6.x M7 port did ask me for one, but didn't accept the correct one.