if i understood it corectly, which is entirely possible im clueless, vaults uses cryptfs/encrptfs. like i think there's a few options from like blowfish and ...crap something about a squid lol. i've used it in the past with general success, however, that can be lost in a time of unintended shutdowns or system lock ups. which honestly seems fine to me but, it's worth mentioning as i've lost a few things after a usb install froze up.

edit: old af but - https://www.fsl.cs.sunysb.edu/docs/cryptfs/cryptfs.html