[dm-devel] xts fuzz testing and lack of ciphertext stealing support

[Herbert Xu]

On Thu, Jul 18, 2019 at 03:43:28PM +0000, Pascal Van Leeuwen wrote:
>
> Hmmm ... so the generic CTS template would have to figure out whether it is wrapped 
> around ECB, CBC, XTS or whatever and then adjust to that?

That's not hard to do.  Right now cts only supports cbc.  IOW
if you pass it anything else it will refuse to instantiate.

> For XTS, you have this additional curve ball being thrown in called the "tweak".
> For encryption, the underlying "xts" would need to be able to chain the tweak,
> from what I've seen of the source the implementation cannot do that.

You simply use the underlying xts for the first n - 2 blocks and
do the last two by hand.

Cheers,
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
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