From: Ruben Somsen <rsomsen@gmail•com>
To: Dmitry Petukhov <dp@simplexum•com>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] TLA+ specification for Succint Atomic Swap
Date: Thu, 14 May 2020 13:41:32 +0200 [thread overview]
Message-ID: <CAPv7TjYuaj+YN-ByDQmRqnR+QmK6rmtDOJzsad81t5LPCyTcxg@mail.gmail.com> (raw)
In-Reply-To: <20200514120805.521fbaa2@simplexum.com>
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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 <dp@simplexum•com> wrote:
> В Thu, 14 May 2020 07:31:13 +0200
> Ruben Somsen <rsomsen@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
> > 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)
>
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next prev parent reply other threads:[~2020-05-14 11:41 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 17:02 Dmitry Petukhov
2020-05-13 19:03 ` Ruben Somsen
2020-05-14 4:52 ` Dmitry Petukhov
2020-05-14 5:31 ` Ruben Somsen
2020-05-14 7:08 ` Dmitry Petukhov
2020-05-14 11:41 ` Ruben Somsen [this message]
2020-06-01 11:38 ` Dmitry Petukhov
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