linux-kernel - Re: [PATCH 19/22] crypto: inside-secure - add check for xts input length equal to zero

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Date:   Wed, 12 Aug 2020 10:36:32 +1000
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Horia Geantă <horia.geanta@....com>
Cc:     Eric Biggers <ebiggers@...nel.org>,
        "Van Leeuwen, Pascal" <pvanleeuwen@...bus.com>,
        "Andrei Botila (OSS)" <andrei.botila@....nxp.com>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-arm-kernel@...s.com" <linux-arm-kernel@...s.com>,
        Andrei Botila <andrei.botila@....com>,
        Antoine Tenart <antoine.tenart@...tlin.com>
Subject: Re: [PATCH 19/22] crypto: inside-secure - add check for xts input
 length equal to zero

On Tue, Aug 11, 2020 at 06:28:39PM +0300, Horia Geantă wrote:
>
> What about, for example, CBC?
> AFAICT cbc(aes) with input length = 0 is valid.

That's just because CBC accepts any input which is a multiple
of blocksize.

> Same for CTR (with the note that blocksize = 1) and several other algorithms
> mentioned in the cover letter.

CTR accepts any input size.

> What's the rule in these cases?

What input size is accepted depends on the algorithm.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt