Re: [bitcoin-dev] Base64-encoded descriptors

From: Trey Del Bonis <j.delbonis.3@gmail•com>
To: "Spencer Dupre`" <spencer.dupre@gmail•com>,
	 Bitcoin Protocol Discussion
	<bitcoin-dev@lists•linuxfoundation.org>
Subject: Re: [bitcoin-dev] Base64-encoded descriptors
Date: Tue, 24 Dec 2019 20:02:09 -0500	[thread overview]
Message-ID: <CAFUsdzp5d=0ErFZPfyB4Lh84HiCpWB+CfuYWRTfsFOfXL0sz4Q@mail.gmail.com> (raw)
In-Reply-To: <CAOB=H7qZ55XXncp9ovR8YpXwBwoVMO=WmbPS_aRxdqk0dFoEiQ@mail.gmail.com>

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Part of the aversion to using bech32 may be that the BCH code used in
bech32 for error detection doesn't hold up for messages longer than some
length (that I can't remember off the top of my head).  It still encodes
and decodes perfectly well but a decoder won't be guaranteed to detect
potential errors, so that's somewhat wasted there.  Maybe someone should
define a derivatives of bech32 that retains error detection properties for
longer message lengths, such as those used in lightning invoices.

QR codes (as Pavol mentioned) have built-in error detection (using its own
BCH code scheme), somewhat mitigate this when used there.  Although
personally I'm skeptical of how useful payment descriptors are for the
kinds of quick transactions that QR codes work well for.

-Trey

On Tue, Dec 24, 2019, 6:55 PM Spencer Dupre` via bitcoin-dev <
bitcoin-dev@lists•linuxfoundation.org> wrote:

> Sounds like a good UX improvement, but do we really need to introduce a
> new encoding? Perhaps bech32 could be used instead.
>
> On Tue, Dec 24, 2019, 12:07 PM Chris Belcher via bitcoin-dev <
> bitcoin-dev@lists•linuxfoundation.org> wrote:
>
>> I've recently been playing around with descriptors, and they are very
>> nice to work with. They should become the standard for master public
>> keys IMO.
>>
>> One downside is that users cant easily copypaste them to-and-fro to make
>> watch-only wallet. The descriptors contain parenthesis and commas which
>> stop highlighting by double-clicking. Also the syntax might look scary
>> to newbs.
>>
>> An obvious solution is to base64 encode the descriptors. Then users
>> would get a text blog as the master public key without any extra details
>> to bother them, and developers can easily base64 decode for developing
>> with them.
>>
>> A complication might be the descriptor checksum. If there's a typo in
>> the base64 text then that could decode into multiple character errors in
>> the descriptor, which might be problematic for the checksum. Maybe the
>> descriptor could be base64 encoded without the checksum, then attach the
>> checksum to the end of the base64 text.
>>
>> Thoughts?
>>
>> I didn't come up with these ideas, they came from discussions with
>> achow101.
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