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From:   Kestrel seventyfour <kestrelseventyfour@gmail.com>
Date:   Fri, 7 May 2021 07:41:35 +0200
Message-ID: <CAE9cyGToQUPuU3GfZK1SSTEUts3Ot1x7nAW1QdttvfVNDQqBoQ@mail.gmail.com>
Subject: Re: cannot pass split cryptomgr tests for aes ctr
To:     linux-crypto@vger.kernel.org
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Hi Eric,

thanks for the info. Walksize did the trick returning the chunks.

D. Kestrel

Am Di., 4. Mai 2021 um 18:52 Uhr schrieb Eric Biggers <ebiggers@kernel.org>:
>
> On Mon, May 03, 2021 at 09:56:40AM +0200, Kestrel seventyfour wrote:
> > Hi,
> >
> > I am trying to update the old ifxdeu driver to pass the crypto mgr tests.
> > However, I continously fail to pass the split tests and I wonder what to do.
> >
> > For example, I successfully pass the test vector 0 here:
> > https://elixir.bootlin.com/linux/latest/source/crypto/testmgr.h#L16654
> > if there is no split.
> >
> > But if the text "Single block msg" is split into two 8 byte blocks
> > (single even aligned splits), which end up as separate skcipher walks
> > in the driver, the second block is wrong and does not compare
> > correctly, to what is hardcoded in testmgr.h. Same if I try it with
> > online aes-ctr encoders in the web.
> > I have tried doing the xor manually with the aes encoded iv, but I get
> > the same result as the hardware and if I use the next last iv, I still
> > do not get the second 8 bytes that are hardcoded in cryptomgr.h.
> >
> > Can someone shed a light on it?
> > Is it valid to compare a crypto result that was done on a single walk
> > with 16byte with two separate walks on the 8 byte splits (of the
> > original 16)? Is the cryptomgr test on the split tests expecting that
> > I concat the two walks into a single one?
> > If yes, how to do that on the uneven splits with separations like 15
> > 16 5 byte sequences, etc., fill up the walk up to full block size and
> > spill over into the next walk?
> >
>
> The split test cases expect the same output (same sequence of bytes) as the
> non-split test cases.  The only difference is how the data is split up into
> scatterlist elements.  Yes, that means that a single 16-byte block of the
> keystream may need to be XOR'ed with data from multiple scatterlist elements.
> Take a look at how other drivers handle this.
>
> - Eric