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Subject: Re: [PATCH 0/2] crypto: remove MD4 generic shash
From:   Andrew Bartlett <abartlet@samba.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Jeremy Allison <jra@samba.org>, Steve French <smfrench@gmail.com>,
        linux-cifs <linux-cifs@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        samba-technical <samba-technical@lists.samba.org>,
        David Howells <dhowells@redhat.com>,
        Steve French <sfrench@samba.org>, keyrings@vger.kernel.org,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        Denis Kenzior <denkenz@gmail.com>
Date:   Thu, 19 Aug 2021 17:23:30 +1200
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On Wed, 2021-08-18 at 22:18 -0700, Eric Biggers wrote:

> I'm not sure you understand how embarrassing it is to still be using
> these
> algorithms.  MD4 has been broken for over 25 years, and better
> algorithms have
> been recommended for 29 years.  Similarly MD5 has been broken for 16
> years and
> better algorithms have been recommended for 25 years (though granted,
> HMAC-MD5
> is more secure than plain MD5 when properly used).  Meanwhile SHA-2
> is 20 years
> old and is still considered secure.  So this isn't something that
> changes every
> month -- we're talking about no one bothering to do anything in 30
> years.
> 
> Of course, if cryptography isn't actually applicable to the use case,
> then
> cryptography shouldn't be used at all.

I'm sorry that Samba - or the Kernel, you could implement whatever is
desired between cifs.ko and kcifsd -  hasn't gone it alone to build a
new peer-to-peer mechanism, but absent a Samba-only solution Microsoft
has been asked and has no intention of updating NTLM, so embarrassing
or otherwise this is how it is.

Thankfully only the HMAC-MD5 step in what you mention is
cryptographically significant, the rest are just very lossy compression
algorithms.  

Andrew Bartlett

-- 
Andrew Bartlett (he/him)       https://samba.org/~abartlet/
Samba Team Member (since 2001) https://samba.org
Samba Team Lead, Catalyst IT   https://catalyst.net.nz/services/samba

Samba Development and Support, Catalyst IT - Expert Open Source
Solutions