The tireless developers at Team Win released their custom Android recovery for the Nexus 6P and Nexus 5X last week, but at the time it didn't support decryption. This makes working with the stock software (which Google encrypts by default, gleefully thumbing their noses at the NSA and FBI in a show of customer protection) somewhat tricky. But ROM flashers and phone modders can now use the latest version of TWRP on the Nexus 6P with the encrypted stock software, or any other ROM that uses the feature. The latest version is 18.104.22.168.
Owners of the Nexus 5X will have to wait a bit. After revealing the new N6P's recovery build on Google+, TWRP team member Ethan Yonker said that they are working on the same update for the Nexus 5X, but are understandably hampered by not actually having the phone in their possession. Considering the speed at which TWRP moves for flagship phones (and sometimes even for more obscure devices), N5X owners probably won't be waiting for very long.
And what do you know, here it is. Well done, TWRP.