From nobody Thu Jul 8 03:37:39 2021 Return-Path: X-Original-To: cfrg@ietfa.amsl.com Delivered-To: cfrg@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id A12823A1E21 for ; Thu, 8 Jul 2021 03:37:37 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -17.598 X-Spam-Level: X-Spam-Status: No, score=-17.598 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_MED=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, ENV_AND_HDR_SPF_MATCH=-0.5, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001, USER_IN_DEF_DKIM_WL=-7.5, USER_IN_DEF_SPF_WL=-7.5] autolearn=ham autolearn_force=no Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=google.com Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C0kphdXpgszX for ; Thu, 8 Jul 2021 03:37:32 -0700 (PDT) Received: from mail-il1-x129.google.com (mail-il1-x129.google.com [IPv6:2607:f8b0:4864:20::129]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 646DB3A1E23 for ; Thu, 8 Jul 2021 03:37:32 -0700 (PDT) Received: by mail-il1-x129.google.com with SMTP id z1so6198564ils.0 for ; Thu, 08 Jul 2021 03:37:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JToROq3HK3cB/HliGsNyFDRbxuX97+FqP4I9aBLx2UU=; b=Eeb4fZUTs9BChFzFrB08R343NcjAofu1mhOuyE54pdWnNwnUm5/8G/sm21I9pDqYXM Pmx07S2k02jE11BVY+J5cEvbBmO2TN1hdP2vruIEEKd0X38mtin3YknD8cUWV/8S4wMq NRBhLdoVsdWV0fgt+eEygU30HuOWWKZK9P6QwjGgQRkVZNhXfbh+m6r5PA8On1sLgnHP 7vk5mq5LHi4PGUm1SHi2ON0+NobnM8kRid1bzC0yQq78bloM+M/Ho7R6P0/m+NwnE/7r i6vI+E+axXKUHZOGkPLhjiJPLXP2pbBQvGbO2S0OYkdrEJx3JFQwykdSFfzFrjLhNUZv XtBg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JToROq3HK3cB/HliGsNyFDRbxuX97+FqP4I9aBLx2UU=; b=PYKvABVLEJOHl0BirwzoLuILbuwXuveWs1WSrLOaB6vUJxNLdELNoNlJpWtAHJ2gZz /zDM7ca9R27TdDaHO5G8+to3ZZVWEyt1+b4QjyPsG+JqCpOZCfqght75A0X0ncheVrZX sFlkL3qTGu9Ct4LMggfaeiyGCk1n+Yoh0u/AGkU1S8BhLAp09GXpp4cpeWjUWdzwdA07 pEGsKpxaX+FRb1kzvbWHwOzjuRHgAGXEv62qARpSKEgJF71nP8inYQ8lC0Pbr9ok3rus fPBlqbIH8eOvYHV6l3JDoS9n1CprPeo3Jentp9sg7sKTrXAbiVESNAGxAxbXkh0u+G4W 7FJg== X-Gm-Message-State: AOAM530QmhO5C/GHtkTFrpJG5klZ46D5c9XaZPMfTAGfvQk7BpDRQa6z H+9d4XsQrJDkQ9rJAWTNECn7iwOEIJid3HlihA9hDA== X-Google-Smtp-Source: ABdhPJyZrQ1m50SlZO9s6ZOHF0mTCneX4F1NPQhsFMJsrPmSp1bmVD0jAKqsndyKxnaKBNwMeCvQ9L3H5/L3BTSExN4= X-Received: by 2002:a92:710a:: with SMTP id m10mr22001209ilc.254.1625740650249; Thu, 08 Jul 2021 03:37:30 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Ben Laurie Date: Thu, 8 Jul 2021 11:37:18 +0100 Message-ID: To: Phillip Hallam-Baker Cc: IRTF CFRG Content-Type: multipart/alternative; boundary="000000000000f4eb6d05c69a3def" Archived-At: Subject: Re: [CFRG] Threshold Sig required - Random bit flip hits Cert Transparency Log X-BeenThere: cfrg@irtf.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Crypto Forum Research Group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 08 Jul 2021 10:37:38 -0000 --000000000000f4eb6d05c69a3def Content-Type: text/plain; charset="UTF-8" On Wed, 7 Jul 2021 at 17:04, Phillip Hallam-Baker wrote: > So it has actually happened, a one in a billion computing error has caused > a cert transparency log to become corrupted due to a bit flip error. There > is a discussion of the issue here: > > Single random bit flip causes error in certificate transparency log | > Hacker News (ycombinator.com) > > > The solution they obsess over (ECC RAM) is actually irrelevant to the > error in that case as it was an even rarer CPU error. Which means that what > I considered to be a more or less theoretical concern about signing append > only logs turns out to have actually occurred. Do things billions of times > and billion to one chances will happen. > > > The only robust solution to this issue is for redundant notaries to sign > the log. > That's not true - the solution CT uses already is to have multiple redundant logs. > > Consider the case where we have an append only log that is authenticated > by means of a Merkle tree with the apex of the tree being signed at 10 > minute intervals. If we have a single server doing the signing, any error > that occurs will lead to the log becoming invalid. This condition cannot be > distinguished from a notary default. > > But consider the case where there are three notaries each signing the log, > which private key should they use? > > All three signers use the same key means that if an error occurs, we risk > having a correct and incorrect version of the same log being signed. That > means there is a real risk of the incorrect log and signature leaking > somehow. > > All three signers using different keys is also bad because now we have > three independent notaries and the relying party has to do the job of > deciding which one to trust. There is an even greater risk of the wrong log > being relied on at some point. > > A threshold scheme with three shares and a quorum of 2 solves the problem > very neatly. The possibility of an undetected error is now much smaller as > two signers must be hit with an error having exactly the same effect at the > same time. That is a very remote possibility unless the error is somehow > caused by an architectural defect in the CPU. So we should probably choose > separate chipset architectures (Intel, AMD, ARM?) if we want to get to > maximum robustness. > This seems no more robust to me than the existing scheme - in fact it is probably less robust because it is more complex. Also, I'm not sure why a quorum helps - logs are verifiably correct (or not), so what's the quorum for? That requirement also reduces robustness. > > > So how is the FROST draft coming? > > > > _______________________________________________ > CFRG mailing list > CFRG@irtf.org > https://www.irtf.org/mailman/listinfo/cfrg > --000000000000f4eb6d05c69a3def Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


=
On Wed, 7 Jul 2021 at 17:04, Phillip = Hallam-Baker <phill@hallambaker.com> wrote:
So it has actually happened, a one in a billion computing error= has caused a cert transparency log to become corrupted due to a bit flip e= rror. There is a discussion of the issue here:


The solution they obsess over (ECC RAM) is actually irrelevant = to the error in that case as it was an even rarer CPU error. Which means th= at what I considered to be a more or less theoretical concern about signing= append only logs turns out to have actually occurred. Do things billions o= f times and billion to one chances will happen.


The only robust solution to this issue is for redundant not= aries to sign the log.

Th= at's not true - the solution CT uses already is to have multiple redund= ant logs.
=C2=A0
Consider the case where we have an ap= pend only log that is authenticated by means of a Merkle tree with the apex= of the tree being signed at 10 minute intervals. If we have a single=C2=A0= server doing the signing, any error that occurs will lead to the log becomi= ng invalid. This condition=C2=A0cannot be distinguished from a notary defau= lt.

But consider the case where there are three notaries each signing the= log, which private key should they use?

All three signers use the same k= ey means that if an error occurs, we risk having a correct and incorrect ve= rsion of the same log being signed. That means there is a real risk of the = incorrect log and signature leaking somehow.=C2=A0

All three signers usin= g different keys is also bad because now we have three independent notaries= and the relying party has to do the job of deciding which one to trust. Th= ere is an even greater risk of the wrong log being relied on at some point.=

A threshold scheme with three shares and a quorum of 2 solves the proble= m very neatly. The possibility of an undetected error is now much smaller a= s two signers must be hit with an error having exactly the same effect at t= he same time. That is a very remote possibility unless the error is somehow= caused by an architectural defect in the CPU. So we should probably choose= separate chipset architectures (Intel, AMD, ARM?) if we want to get to max= imum robustness.

This see= ms no more robust to me than the existing scheme - in fact it is probably l= ess robust because it is more complex.

Also, I'= ;m not sure why a quorum helps - logs are verifiably correct (or not), so w= hat's the quorum for? That requirement also reduces robustness.=C2=A0
=C2=A0


So how = is the FROST draft coming?



<= /div>
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