Re: [PATCH] crypto: caam - Remove broken arc4 support

[Herbert Xu <herbert@gondor.apana.org.au>]

On Thu, Jul 02, 2020 at 09:27:33AM +0200, Ard Biesheuvel wrote:
> 
> I do wonder if the others are doing any better - n2 and bcm iproc also
> appear to keep the state in the TFM object, while I'd expect the
> setkey() to be a simple memcpy(), and the initial state derivation to
> be part of the encrypt flow, right?

bcm at least appears to be doing the right thing, but of course
without the hardware or a reference manual I can't be sure.

David can probably tell us whether n2 is capable of updating the
state at ent->enc_key_addr after each arc4 operation.

> Maybe we should add a test for this to tcrypt, i.e., do setkey() once
> and do two encryptions of the same input, and check whether we get
> back the original data.

Yes we could certainly add an arc4-only test.  Alternatively we
could kill the only in-kernel user (auth_gss) and then try to
remove the arc4 interface completely (and hope that nobody complains :)

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