Return-Path: Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 2B8A8C016F for ; Thu, 14 May 2020 11:41:50 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 1A28E888E5 for ; Thu, 14 May 2020 11:41:50 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id C3dhIX0BgUWs for ; Thu, 14 May 2020 11:41:49 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail-ed1-f51.google.com (mail-ed1-f51.google.com [209.85.208.51]) by hemlock.osuosl.org (Postfix) with ESMTPS id 0A278888B6 for ; Thu, 14 May 2020 11:41:49 +0000 (UTC) Received: by mail-ed1-f51.google.com with SMTP id bs4so2105639edb.6 for ; Thu, 14 May 2020 04:41:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Qz8HUvwai8YkAA7Utlu+CjU422AFWmmMcp0LJNceeyM=; b=IYHKM4MHYitVbTiQmUWC90IqQZyzUITWzcvYWnkUqZA6IjuaCRXi9ZbN1jP3jq7WGu qE37gn8OOEy+3zooVkSCzpPWZbHwndeJewFBmuLdO4zsEyi1zFAHu2oKfof6Zz0uZGt8 Tbszg8/DxyzjmIadKKdz5AgBk5flRjXMpJwbUrWgurVFIa+6WyHlxw3BpWHthLVV0dEW COOTMmEdDSrIOK9j4w9LY/moAm9gZ6300j+zFte9VITz1PSVRT3IJ640YokZZRN42aTp GfzSKY9oDlVsKx6dBJWq3D5jhh7UDHvbEns5pMDvw6GVOkvWlHqDyror2dXXbj63Sou4 EhYw== 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=Qz8HUvwai8YkAA7Utlu+CjU422AFWmmMcp0LJNceeyM=; b=BO91+YXBNn/ep7DpBijOqZ7dOkJvwVR2eKOigORCQ/3Xr91/Wgv06Nzqk3RWJy0LeO sk38UK6aVLTRYDJdvvnkz2iZSEu2RF91yku7wsP1RT48r10t7do8FzRwxNs7sFSwA+Iz 5FCYgYL09dPsCVag0BIf3EJhfiqKqyyiz89AwulT7/Y51Ta9Q8/jz9n5A3JKJtFuvi4n F52utLKVbLjn4DTLHYKgtqcDQ49230lQptK/Ocj7lXGsRYvUGXd8+feqD1YFTakWfrWd k0x/EZYC9P3kI0RMMii6vm+CSCYQLqMc1BaYyjC+1Z0IlRvNsqEOd2uWCJau2nmPHv1x p8Ow== X-Gm-Message-State: AOAM531EaT9Km0r6QO05fbvn/Byg8JY7vqRk0xg01RvR5/ukuZDoRH2l m+R1olXL7DAxLvnassx4NWEw3tmc1zV2sfeRelA= X-Google-Smtp-Source: ABdhPJwMiyIwn0PS23Y/UtjA0MW8cTmRBTPVd6h+bzs+weDB5nGpaYVErfvQHx4et/HTxYoDm5X6MfXG+/DNzvkQiEo= X-Received: by 2002:a50:9b58:: with SMTP id a24mr3289648edj.256.1589456507333; Thu, 14 May 2020 04:41:47 -0700 (PDT) MIME-Version: 1.0 References: <20200513220222.24953c0a@simplexum.com> <20200514095215.4ea20666@simplexum.com> <20200514120805.521fbaa2@simplexum.com> In-Reply-To: <20200514120805.521fbaa2@simplexum.com> From: Ruben Somsen Date: Thu, 14 May 2020 13:41:32 +0200 Message-ID: To: Dmitry Petukhov Content-Type: multipart/alternative; boundary="00000000000081739705a59a2eb4" X-Mailman-Approved-At: Thu, 14 May 2020 11:42:45 +0000 Cc: Bitcoin Protocol Discussion Subject: Re: [bitcoin-dev] TLA+ specification for Succint Atomic Swap X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 14 May 2020 11:41:50 -0000 --00000000000081739705a59a2eb4 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Dmitry, >But it should be noted that it is not enough that Bob publishes success_tx before refund_tx_1 became valid. The success_tx needs to be confirmed before refund_tx_1 became valid. Agreed, my write-up would benefit from pointing this out more explicitly. Cheers, Ruben On Thu, May 14, 2020 at 9:05 AM Dmitry Petukhov wrote: > =D0=92 Thu, 14 May 2020 07:31:13 +0200 > Ruben Somsen wrote: > > > Hi Dmitry, > > > > >While refund_tx_1 is in the mempool, Bob gives success_tx to the > > >friendly miner > > > > I see, so you're talking about prior to protocol completion, right > > after Alice sends Bob the success_tx. The reason this is not an issue > > is because Alice and Bob both had to misbehave in order for this to > > happen. Bob is misbehaving here because he should have published the > > success_tx before refund_tx_1 became valid, and Alice is misbehaving > > here because she should have sent the revoke_tx (which invalidates > > the success_tx) followed by refund_tx_2 (revealing her secret only > > AFTER Bob can no longer claim the BTC). In other words: yes, the > > protocol can fail if Alice and Bob together work towards that goal. A > > feature, not a bug. This won't happen if either of them doesn't want > > it to. I imagine this is difficult to model. > > Right. But it should be noted that it is not enough that Bob publishes > success_tx before refund_tx_1 became valid. The success_tx needs to be > confirmed before refund_tx_1 became valid. > > Only Bob can spend success_tx so this is unlikely to be the practical > problem, unless the original fee of success_tx is too small and Bob > epically screws up CPFP-ing it. > > > >Bob will receive BTC, and the LTC can be locked forever, but Bob > > >doesn't > > care, he got his BTC. > > > > No, because diagram step 5 comes before step 6 -- Alice won't give > > her key until she learns secretBob. > > I somehow missed it, and steps 5 and 6 in the diagram was not modelled > at all (on the other hand, it made the model simpler and I had > something working relatively quick). I now made the `signers_map` into > variable that can be changed to give Bob the ability to sign for Alice. > > With that change, step 6 can be modelled, but this will add a bunch of > new txs to the model (each Alice&Bob spend will have 'Bob unilateral > override' case) > --00000000000081739705a59a2eb4 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi Dmitry,

>But it should be noted t= hat it is not enough that Bob publishes success_tx before refund_tx_1 becam= e valid. The success_tx needs to be confirmed before refund_tx_1 became val= id.

Agreed, my write-up would benefit from poi= nting this out more explicitly.

Cheers,
= Ruben

On Thu, May 14, 2020 at 9:05 AM Dmitry Petukhov <dp@simplexum.com> wrote:
=D0=92 Thu, 14 May 2020 07:31:13 +0= 200
Ruben Somsen <rso= msen@gmail.com> wrote:

> Hi Dmitry,
>
> >While refund_tx_1 is in the mempool, Bob gives success_tx to the > >friendly miner
>
> I see, so you're talking about prior to protocol completion, right=
> after Alice sends Bob the success_tx. The reason this is not an issue<= br> > is because Alice and Bob both had to misbehave in order for this to > happen. Bob is misbehaving here because he should have published the > success_tx before refund_tx_1 became valid, and Alice is misbehaving > here because she should have sent the revoke_tx (which invalidates
> the success_tx) followed by refund_tx_2 (revealing her secret only
> AFTER Bob can no longer claim the BTC). In other words: yes, the
> protocol can fail if Alice and Bob together work towards that goal. A<= br> > feature, not a bug. This won't happen if either of them doesn'= t want
> it to. I imagine this is difficult to model.

Right. But it should be noted that it is not enough that Bob publishes
success_tx before refund_tx_1 became valid. The success_tx needs to be
confirmed before refund_tx_1 became valid.

Only Bob can spend success_tx so this is unlikely to be the practical
problem, unless the original fee of success_tx is too small and Bob
epically screws up CPFP-ing it.

> >Bob will receive BTC, and the LTC can be locked forever, but Bob > >doesn't=C2=A0
> care, he got his BTC.
>
> No, because diagram step 5 comes before step 6 -- Alice won't give=
> her key until she learns secretBob.

I somehow missed it, and steps 5 and 6 in the diagram was not modelled
at all (on the other hand, it made the model simpler and I had
something working relatively quick). I now made the `signers_map` into
variable that can be changed to give Bob the ability to sign for Alice.

With that change, step 6 can be modelled, but this will add a bunch of
new txs to the model (each Alice&Bob spend will have 'Bob unilatera= l
override' case)
--00000000000081739705a59a2eb4--