From: Peter Todd <pete@petertodd•org>
To: Gregory Maxwell <greg@xiph•org>
Cc: Bitcoin Protocol Discussion <bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Address expiration times should be added to BIP-173
Date: Thu, 28 Sep 2017 21:50:48 -0400 [thread overview]
Message-ID: <20170929015048.GC11956@savin.petertodd.org> (raw)
In-Reply-To: <CAAS2fgRpMXdqKXeYSOtVBQQ9fmu=nQ9anEO6Wrc_5rms1Y2B2w@mail.gmail.com>
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On Thu, Sep 28, 2017 at 12:58:30AM +0000, Gregory Maxwell wrote:
> On Wed, Sep 27, 2017 at 4:06 PM, Peter Todd via bitcoin-dev
> <bitcoin-dev@lists•linuxfoundation.org> wrote:
> > Re-use of old addresses is a major problem, not only for privacy, but also
> > operationally: services like exchanges frequently have problems with users
> > sending funds to addresses whose private keys have been lost or stolen; there
>
> When Pieter and I were working on Bech32 we specifically designed for
> error correcting codes that had good performance for longer lengths
> than we technically needed specifically to incorporate things like
> dates and explicit amounts.
>
> (explicit amounts so that typos and bit flips in amounts displayed or
> in memory couldn't result in sending the wrong amount)
>
> But we also thought that also adding those features at the same time
> would retard adoption-- both due to debating over the encodings and
> because handling would result in different software requirements and
> layering, so you couldn't just drop them in.
Notably, even something as simple as adding a new type of confirmation window
that might be needed is a big chance to UI logic.
> Doubly unfortunately, people have even deployed BIP173 already (prior
> to it even having much peer review or being adopted by its own
> authors), so I think a rethink now wouldn't be timely (I mean as a
> replacement to BIP173 rather than an additional format). :(
Yeah, I just noticed Pieter Wuille's BIP173-including segwit pull-req - that's
a lot of code that would get touched by this proposal, so it's likely too late
in the process.
> But I do support the idea.
>
> One thing to keep in mind is that address format linked fields are
> most efficient if they're multiples of 5 bits. Perhaps use 1 bit to
> indicate an embedded amount and 19 bits of 1 day precision, resulting
> in a 1435 year span.
What do you mean by "an embedded amount"?
> Keep in mind that high precision of the expiration times is asking the
> sender to have a higher precision of idea of the time, date only is
> kinda nice. I think shorter expiration times are unlikely to be
> useful due to clock skew-- you can't assume a signer has any access to
> the Bitcoin network at all.
I'm inclined to agree as well. Also, Bitcoin payments themselves are inherently
imprecise, because blocks aren't found on a regular interval - Coinbase's "10
minute" payment expiry window is odd from that point of view.
Having said that, you'd want a resolution more precise than what you'd expect
timeouts to be set at, to avoid UI "fencepost" oddity; if I want to set a 1 day
timeout, users shouldn't see either 1 or 2 days depending on exactly which way
it happened to be rounded that particular time..
--
https://petertodd.org 'peter'[:-1]@petertodd.org
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next prev parent reply other threads:[~2017-09-29 1:51 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-27 16:06 Peter Todd
2017-09-27 18:15 ` CryptAxe
2017-09-27 19:03 ` Mark Friedenbach
2017-09-27 21:20 ` Peter Todd
2017-09-27 19:35 ` Chris Priest
2017-09-27 20:11 ` CryptAxe
2017-09-27 20:23 ` Nick Pudar
2017-09-27 20:19 ` CryptAxe
2017-09-27 21:09 ` Mark Friedenbach
2017-09-27 21:15 ` Peter Todd
2017-09-28 0:22 ` Gregory Maxwell
2017-09-27 21:33 ` Peter Todd
2017-09-28 0:58 ` Gregory Maxwell
2017-09-29 1:50 ` Peter Todd [this message]
2017-09-29 2:06 ` Gregory Maxwell
2017-09-28 10:09 ` Andreas Schildbach
2017-09-28 12:43 ` Sjors Provoost
2017-09-28 14:13 ` Andreas Schildbach
2017-09-28 14:41 ` Sjors Provoost
2017-09-28 15:06 ` Andreas Schildbach
2017-09-28 15:45 ` Sjors Provoost
2017-09-28 16:59 ` Luke Dashjr
2017-09-29 2:18 ` Peter Todd
2017-09-29 7:18 ` Sjors Provoost
2017-09-29 2:55 ` [bitcoin-dev] Why the BIP-72 Payment Protocol URI Standard is Insecure Against MITM Attacks Peter Todd
2017-09-29 4:21 ` Omar Shibli
2017-09-29 13:14 ` Tomas
2017-09-29 17:40 ` Aymeric Vitte
2017-09-30 15:33 ` Andreas Schildbach
2017-09-29 1:45 ` [bitcoin-dev] Address expiration times should be added to BIP-173 Peter Todd
2017-09-29 8:44 ` Andreas Schildbach
2017-09-29 9:55 ` Peter Todd
2017-09-29 12:45 ` Andreas Schildbach
2017-09-29 13:52 ` Peter Todd
2017-09-29 17:25 ` Gregory Maxwell
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