From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3C6DB1CF96; Sun, 3 Aug 2025 22:27:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=63.228.1.57 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754260029; cv=none; b=TBXxXVX72R97BORIDjW6ypXDkWV0DQvZOxeq9NNv3p2O8UZYV6HNe6jo9PKEfUTX6mi7TtgwQhSpUGIQHnOgz1Zm17bnB35uFatvfOOcuD8Kb3dMU51KzSNCqiiat5OqKyjIodsijjmQMCoG4OSc5vF/XAQn+ptbpA9w5zcEmf0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754260029; c=relaxed/simple; bh=FkkVRJp5hZd8KkpzRG0aUfu8hIB8Abc4p8uJysAO5Co=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=isG2TjpAoYK64Vknt97D6jGdM0JVbESniTLxsmZu9o5LvtNeMZJuWUukyWD3P7UZZV9uybc91deUTbOa53sLEUS+NgVOv3HIWxDTYOsvWUvfPBzpLJpEKUBWn6jPvylnm8z/ln5csE9CE4VHK90pVW9p4HUl4+RcJK0ge4yZbMk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org; spf=pass smtp.mailfrom=kernel.crashing.org; arc=none smtp.client-ip=63.228.1.57 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.crashing.org Received: from gate.crashing.org (localhost [127.0.0.1]) by gate.crashing.org (8.18.1/8.18.1/Debian-2) with ESMTP id 573MR2Ob1823279; Sun, 3 Aug 2025 17:27:02 -0500 Received: (from segher@localhost) by gate.crashing.org (8.18.1/8.18.1/Submit) id 573MR1Ii1823278; Sun, 3 Aug 2025 17:27:01 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Sun, 3 Aug 2025 17:27:01 -0500 From: Segher Boessenkool To: Eric Biggers Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Ard Biesheuvel , "Jason A . Donenfeld" , linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org Subject: Re: [PATCH 3/7] crypto: powerpc/md5 - Remove PowerPC optimized MD5 code Message-ID: References: <20250803204433.75703-1-ebiggers@kernel.org> <20250803204433.75703-4-ebiggers@kernel.org> <20250803221438.GA119835@quark> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250803221438.GA119835@quark> On Sun, Aug 03, 2025 at 03:14:38PM -0700, Eric Biggers wrote: > On Sun, Aug 03, 2025 at 05:07:10PM -0500, Segher Boessenkool wrote: > > On Sun, Aug 03, 2025 at 01:44:29PM -0700, Eric Biggers wrote: > > > MD5 is insecure, > > > > Really? Have you found an attack? Can you explain it to the rest of > > the world? > > > > MD5 is not recommended for future cryptographic purposes, there have > > been some collission "attacks" on it (quotes because such a thing is > > never an attack at all, merely an indication that not all is well with > > it, somewhere in the future an actual vulnerability might be found). > > > > Since there are newer, better, *cheaper* alternatives available, of > > course you should not use MD5 for anything new anymore. But claiming it > > is insecure is FUD. > > Many attacks, including practical attacks, have been found on MD5 over > the past few decades. Check out https://en.wikipedia.org/wiki/MD5 There is no new information on that page. There are no practical attacks mentioned there, either, just some collission things (which never can be practical attacks for most applications). > > > This commit removes the PowerPC optimized MD5 code. > > > > Why? It would help to have real arguments for it! > > Sure, check out the commit message which mentioned multiple reasons why > maintaining this code is not worthwhile. Of course I have read that, but that information went missing, if you intended to provide it :-( You are replacing a known-working target implementation by a lower performance generic implementation. But is that one known-working at all? Does it come with tests? Was it tested to have the same outputs as the existing thing, maybe? Just on a few inputs maybe. We were not told anything like that. Segher