netdev - Re: [RFC PATCH 2/8] crypto/krb5: Provide Kerberos 5 crypto through AEAD API

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Message-ID: <1485676.1736504798@warthog.procyon.org.uk>
Date: Fri, 10 Jan 2025 10:26:38 +0000
From: David Howells <dhowells@...hat.com>
To: Herbert Xu <herbert@...dor.apana.org.au>
Cc: dhowells@...hat.com, Chuck Lever <chuck.lever@...cle.com>,
    Trond Myklebust <trond.myklebust@...merspace.com>,
    "David S. Miller" <davem@...emloft.net>,
    Marc Dionne <marc.dionne@...istor.com>,
    Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
    Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
    linux-crypto@...r.kernel.org, linux-afs@...ts.infradead.org,
    linux-nfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
    netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/8] crypto/krb5: Provide Kerberos 5 crypto through AEAD API

Herbert Xu <herbert@...dor.apana.org.au> wrote:

> rfc8009 is basically the same as authenc.  So rather than being an
> AEAD algorithm it should really be an AEAD template which takes a
> cipher and and a hash as its parameters.

That's only half true.  If it's acting in checksum mode then it's not an
authenc() algo.

> In fact, you could probably use authenc directly.

However the point of having a library is to abstract those details from the
callers.  You wanted me to rewrite the library as AEAD algorithms, which I
have done as far as I can.  This makes the object for each kerberos enctype
look the same from the PoV of the clients.

I have plans to make the kerberos AEAD use an authenc behind the scenes rather
than a cipher plus hash where appropriate as a future evolution, but the
optimised authenc drivers (QAT for example) that I can find don't appear to
support CTS.

So I'm not sure what it is you were envisioning.

David