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From: Andrew Bartlett <abartlet@samba.org>
To: Jeremy Allison <jra@samba.org>, Steve French <smfrench@gmail.com>
Cc: linux-cifs <linux-cifs@vger.kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	Eric Biggers <ebiggers@kernel.org>,
	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>
Subject: Re: [PATCH 0/2] crypto: remove MD4 generic shash
Date: Thu, 19 Aug 2021 15:49:14 +1200	[thread overview]
Message-ID: <d08c99b8550cc48fe04cc9f4cd5eca0532f5733d.camel@samba.org> (raw)
In-Reply-To: <YR2E2FZNdMj2xl+0@jeremy-acer>

On Wed, 2021-08-18 at 15:08 -0700, Jeremy Allison via samba-technical
wrote:
> 
> My 2 cents. Preventing NTLM authentication/signing from working would
> be
> a negative for the Linux kernel client. I don't mind if that code has
> to be isolated inside cifs.ko, but it really needs to keep working,
> at least until we have a pluggable client auth in cifs.ko and Samba
> that allows the single-server (non AD-Domain) case to keep working
> easily.

I would echo that, and also just remind folks that MD4 in NTLMSSP is
used as a compression only, it has no security value.  The security
would be the same if the password was compressed with MD4, SHA1 or
SHA256 - the security comes from the complexity of the password and the
HMAC-MD5 rounds inside NTLMv2.  

I'll also mention the use of MD4, which is used to re-encrypt a short-
term key with the long-term key out of the NTLMv2 scheme.  This
thankfully is an unchecksumed simple RC4 round of one random value with
another, so not subject to known-plaintext attacks here.

I know neither MD4 nor HMAC-MD5 is not flavour of the month any more,
with good reason, but we would not want to go with way of NFSv4 which
is, as I understand it, full Kerberos or bust (so folks choose no
protection).

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


  reply	other threads:[~2021-08-19  3:49 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-18 14:46 Ard Biesheuvel
2021-08-18 14:51 ` Denis Kenzior
2021-08-18 16:10   ` Ard Biesheuvel
2021-08-18 16:23     ` Denis Kenzior
2021-08-18 16:47       ` Steve French
2021-08-18 22:08         ` Jeremy Allison
2021-08-19  3:49           ` Andrew Bartlett [this message]
2021-08-19  5:18             ` Eric Biggers
2021-08-19  5:23               ` Andrew Bartlett
2021-08-18 21:11       ` ronnie sahlberg
2021-08-18 22:10       ` Ard Biesheuvel
2021-08-18 22:22         ` Denis Kenzior
2021-08-18 23:03           ` Steve French
2021-08-19 16:56             ` Denis Kenzior
2021-08-19 10:42     ` Jarkko Sakkinen
2021-08-19 17:10       ` Steve French
2021-08-19 20:54         ` ronnie sahlberg

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