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by gray_charger 1515 days ago
Is AES-XTS a secure mode? Or is that something else?
1 comments

XTS is often used in disk encryption (or it was a few years ago when I worked on at-rest data encryption for a storage product at a major vendor).

It uses the sector number and block offset within the sector as input, a little like a counter mode. Its major advantage is zero overhead, so you don't lose disk capacity, or need to map blocks around, you can just sorta use it as a filter layer in your disk reads/writes.

It's not properly authenticated though, as data tampering can result in altered or scrambled plaintext rather than detectable errors, so you need other mechanisms for error detection, which then have to be secure against attacks.