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From: Peter Todd <pete@petertodd.org>
To: Sean Bowe <sean@z.cash>,
	Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] BIP draft: HTLC transactions
Date: Wed, 20 Jul 2016 01:46:54 -0400	[thread overview]
Message-ID: <20160720054654.GA1420@fedora-21-dvm> (raw)
In-Reply-To: <CAKazn3mKUMMz0wyqTsgbkd4mBLgvG2PXziXhgRTi4hX_ApbPhg@mail.gmail.com>

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On Tue, Jul 19, 2016 at 10:35:39PM -0600, Sean Bowe via bitcoin-dev wrote:
> I'm requesting feedback for Hash Time-Locked Contract (HTLC) transactions
> in Bitcoin.
> 
> HTLC transactions allow you to pay for the preimage of a hash. CSV/CLTV can
> be used to recover your funds if the other party is not cooperative. These
> scripts take the following general form:
> 
>     [HASHOP] <digest> OP_EQUAL
>     OP_IF
>         <seller pubkey>
>     OP_ELSE
>         <num> [TIMEOUTOP] OP_DROP <buyer pubkey>
>     OP_ENDIF
>     OP_CHECKSIG

Note that because you're hashing the top item on the stack regardless
scriptSig's that satisfy HTLC's are malleable: that top stack item can be
changed anything in the digest-not-provided case and the script still passes.

-- 
https://petertodd.org 'peter'[:-1]@petertodd.org

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  reply	other threads:[~2016-07-20  5:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-20  4:35 [bitcoin-dev] BIP draft: HTLC transactions Sean Bowe
2016-07-20  5:46 ` Peter Todd [this message]
2016-07-20  6:17   ` Luke Dashjr
2016-08-09  0:46     ` Peter Todd
2016-08-17 10:00     ` Johnson Lau

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