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From: Peter Todd <pete@petertodd.org>
To: Mike Hearn <mike@plan99.net>
Cc: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Subject: Re: [Bitcoin-development] Multisign payment protocol?
Date: Wed, 12 Mar 2014 12:24:58 -0400	[thread overview]
Message-ID: <20140312162458.GA2337@savin> (raw)
In-Reply-To: <CANEZrP1rfHzSrkWGeuNB07Gy9OBj9a+AfY7deQgJzg4TX_QMMg@mail.gmail.com>

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On Wed, Mar 12, 2014 at 05:14:25PM +0100, Mike Hearn wrote:
> >
> > Can this be calculated in advance knowing the initial transaction size and
> > the number of signatures required?
> >
> 
> Sure of course. You assume each signature to be placed in the tx is 73
> bytes. Not very hard, but if the tx you get back from the API doesn't
> contain such a 73-byte sentinel value then it's harder to be sure that this
> part was done correctly.

Multisig signing is an example of untrusted input from an adversary;
this is a good example where you'd be better off just handling it
correctly rather than trying to "make it easier". (although handling it
correctly may include internally converting every not-yet-signed dummy
signature into a 73 bytes pushdata prior to calculating the size)

-- 
'peter'[:-1]@petertodd.org
0000000000000000e18643801741dc70db6fda175230012b0f697024218cd9ef

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  reply	other threads:[~2014-03-12 16:25 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-10 17:39 [Bitcoin-development] Multisign payment protocol? Drak
2014-03-10 17:49 ` Gavin Andresen
2014-03-10 18:01   ` Alan Reiner
2014-03-11  0:04     ` kjj
2014-03-11  0:09       ` Alan Reiner
2014-03-11  0:14         ` Jeff Garzik
2014-03-11  1:15           ` Gavin Andresen
2014-03-11 11:43             ` Drak
2014-03-11 12:38               ` Jeff Garzik
2014-03-11 13:51                 ` Gavin Andresen
2014-03-11 14:13                   ` Jeff Garzik
2014-03-11 14:23                     ` Gavin Andresen
2014-03-11 14:34                       ` Jeff Garzik
2014-03-11 14:44                       ` Jeff Garzik
2014-03-11 14:53                         ` Gary Rowe
2014-03-11 15:18                           ` Mike Hearn
2014-03-11 17:11                             ` Miron
2014-03-11 15:37                           ` Thomas Voegtlin
2014-03-11 21:12                     ` Peter Todd
2014-03-11 17:41                   ` Odinn Cyberguerrilla
2014-03-12  0:29                     ` Jean-Pierre Rupp
2014-03-12  2:35                       ` Alan Reiner
2014-03-12  2:48                         ` Eric Lombrozo
2014-03-12  9:48                           ` Mike Hearn
2014-03-12 15:35                             ` Jeff Garzik
2014-03-12 16:02                               ` Mike Hearn
2014-03-12 16:09                                 ` Drak
2014-03-12 16:14                                   ` Mike Hearn
2014-03-12 16:24                                     ` Peter Todd [this message]
2014-03-12 16:33                                 ` Jeff Garzik
2014-03-12 16:41                                   ` Mike Hearn
2014-03-12 16:47                                     ` Peter Todd
2014-03-12 16:57                                     ` Jeff Garzik
2014-03-10 17:50 ` Mike Hearn
2014-03-10 18:12 ` Jeff Garzik

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