MIME-Version: 1.0
References: <ZM03twumu88V2NFH@petertodd.org>
In-Reply-To: <ZM03twumu88V2NFH@petertodd.org>
From: Samson Mow <samson.mow@gmail.com>
Date: Fri, 4 Aug 2023 11:41:39 -0700
Message-ID: <CAAWeQ5fRi3AiZpSm4riyrNyCRphi5dSE6tFpkaGeQCY3x4keng@mail.gmail.com>
To: Peter Todd <pete@petertodd.org>, 
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary="000000000000dbdc1706021d403b"
Subject: Re: [bitcoin-dev] BIP-352 Silent Payments addresses should have an
 expiration time
Precedence: list

--000000000000dbdc1706021d403b
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Why the 180 year limit? imho should plan for longer.

On Fri, Aug 4, 2023 at 10:41=E2=80=AFAM Peter Todd via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> tl;dr: Wallets don't last forever. They are often compromised or lost. Wh=
en
> this happens, the addresses generated from those wallets become a form of
> toxic
> data: funds sent to those addresses can be easily lost forever.
>
> All Bitcoin addresses have this problem. But at least existing Bitcoin
> addresses aren't supposed to be reused. Silent Payments are: the whole
> point is
> to have a single address that you can safely pay to multiple times, witho=
ut
> privacy concerns. Failing to make Silent Payment addresses eventually
> expire in
> a reasonable amount of time is thus a particularly harmful mistake.
>
> Fixing this is easy: add a 3 byte field to silent payments addresses,
> encoding
> the expiration date in terms of days after some epoch. 2^24 days is 45,00=
0
> years, more than enough. Indeed, 2 bytes is probably fine too: 2^16 days
> is 180
> years. We'll be lucky if Bitcoin still exists in 180 years.
>
> Wallets should pick a reasonable default, eg 1 year, for newly created
> addresses. Attempts to pay an expired address should just fail with a
> simple
> "address expired". Lightning invoices are a good example here: while
> invoices
> does not require expiration from a technical point of view, they do expir=
e
> for
> similar UX reasons as applies to silent payments.
>
> --
> https://petertodd.org 'peter'[:-1]@petertodd.org
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

--000000000000dbdc1706021d403b
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">Why the 180 year limit? imho should plan for longer.</div>=
<br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_attr">On Fri=
, Aug 4, 2023 at 10:41=E2=80=AFAM Peter Todd via bitcoin-dev &lt;<a href=3D=
"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfound=
ation.org</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=
=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding=
-left:1ex">tl;dr: Wallets don&#39;t last forever. They are often compromise=
d or lost. When<br>
this happens, the addresses generated from those wallets become a form of t=
oxic<br>
data: funds sent to those addresses can be easily lost forever.<br>
<br>
All Bitcoin addresses have this problem. But at least existing Bitcoin<br>
addresses aren&#39;t supposed to be reused. Silent Payments are: the whole =
point is<br>
to have a single address that you can safely pay to multiple times, without=
<br>
privacy concerns. Failing to make Silent Payment addresses eventually expir=
e in<br>
a reasonable amount of time is thus a particularly harmful mistake.<br>
<br>
Fixing this is easy: add a 3 byte field to silent payments addresses, encod=
ing<br>
the expiration date in terms of days after some epoch. 2^24 days is 45,000<=
br>
years, more than enough. Indeed, 2 bytes is probably fine too: 2^16 days is=
 180<br>
years. We&#39;ll be lucky if Bitcoin still exists in 180 years.<br>
<br>
Wallets should pick a reasonable default, eg 1 year, for newly created<br>
addresses. Attempts to pay an expired address should just fail with a simpl=
e<br>
&quot;address expired&quot;. Lightning invoices are a good example here: wh=
ile invoices<br>
does not require expiration from a technical point of view, they do expire =
for<br>
similar UX reasons as applies to silent payments.<br>
<br>
-- <br>
<a href=3D"https://petertodd.org" rel=3D"noreferrer" target=3D"_blank">http=
s://petertodd.org</a> &#39;peter&#39;[:-1]@<a href=3D"http://petertodd.org"=
 rel=3D"noreferrer" target=3D"_blank">petertodd.org</a><br>
_______________________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org" target=3D"_blank">=
bitcoin-dev@lists.linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
rel=3D"noreferrer" target=3D"_blank">https://lists.linuxfoundation.org/mail=
man/listinfo/bitcoin-dev</a><br>
</blockquote></div>

--000000000000dbdc1706021d403b--