[dm-devel] [PATCH v3 1/6] crypto: essiv - create wrapper template for ESSIV generation

[Herbert Xu]

On Thu, Jun 20, 2019 at 09:13:25AM +0800, Herbert Xu wrote:
> On Wed, Jun 19, 2019 at 06:04:17PM -0700, Eric Biggers wrote:
> >
> > > +#define ESSIV_IV_SIZE		sizeof(u64)	// IV size of the outer algo
> > > +#define MAX_INNER_IV_SIZE	16		// max IV size of inner algo
> > 
> > Why does the outer algorithm declare a smaller IV size?  Shouldn't it just be
> > the same as the inner algorithm's?
> 
> In general we allow outer algorithms to have distinct IV sizes
> compared to the inner algorithm.  For example, rfc4106 has a
> different IV size compared to gcm.
> 
> In this case, the outer IV size is the block number so that's
> presumably why 64 bits is sufficient.  Do you forsee a case where
> we need 128-bit block numbers?

Actually this reminds me, the essiv template needs to be able to
handle multiple blocks/sectors, as otherwise this will still only
be able to push a single block/sector to the hardware at a time.

Thanks,
-- 
Email: Herbert Xu <herbert at gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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