[Bitcoin-ml] Proposal to deploy cashaddr January, 14

Lucas Clemente Vella lvella at gmail.com
Wed Nov 15 02:02:34 UTC 2017


I agree that is desirable to have a different address format, for the
reason Amaury explained, but I noticed that the proposed is very similar to
BIP173. First let me say that I am not convinced about base 32, but more on
that later.

I could identify two differences from the proposed spec to BIP173:
 - Separator is ':' instead of '1'
 - It is valid to omit the prefix

The first difference is so small I don't find it justifiable. I don't think
it is worth to increase the complexity for implementations that have any
relation with Bitcoin Segwit just so we can use ':' instead of '1'. For
instance, Electron Cash is based on Electrum, whose latest version already
support Bech32 as specified in BIP173.

The second difference is not an improvement, is a setback. It worsens the
user experience. Since addresses with omitted prefixes are shorter, they
should see more usage, and users will lose the ability to easily identify
what currency that address is referring to by simply looking at the string.
I strongly believe the prefix should be mandatory, and since 'bitcoincash'
is too long (I assume it was chosen this long because it wouldn't be
mandatory), I suggest some other smaller string to be used instead, like
'bch' or simply 'cs' (from cash) or something of the sort. If the prefix is
mandatory, them the case for my first point is strengthened: using '1'
instead of ':' allow me to simply double click the alphanumeric string to
select it as whole (that is the original reason for using '1', I believe).

So, if we are going to use this proposal at all, I am strongly in favor of
making it closer to bech32, for the reasons I explained.

That said, I don't like the change from base 58 to base 32, as it is less
space efficient in ASCII. The choice was a trade-off.

Advantages of base 32 over base 58:
 - facilitates reading out loud the address (as all letters have the same
case);
 - facilitates handwriting down the address (same reason);
 - Improves space efficiency in QR-Codes by 45%.

Disadvantage:
 - increases the number of characters by 15% on the most common case of
P2KH address.

I am mildly against it because 99% of the addresses I interact with are
written in text, on a screen, and I dislike the aesthetics of big
horizontal words (and how they can mess up paragraph breaks when inlined
inside a text).

Is that a good reason? Given how seldom I have to write down addresses (or
read them aloud), and how current QR-Codes work perfectly fine (and I do
believe the better alternative would be to simply devise an specific
encoding for QR-Codes, since they already have error correction), I do
believe it is a justifiable opposition.

To summarize my position:
 - Mildly against base 32, prefer old base 58;
 - Strongly against allowing to drop the prefix from the address, for it
makes them easier to identify;
 - As consequence of the above, I am also strongly against using ':'
instead of '1' as a separator.

I agree with the choice for BCH for error detection, as it seems everybody
agree it is faster, and no less safer. I don't have an opinion on the
meaning of the version byte.

2017-11-14 22:25 GMT-02:00 Amaury Séchet via bitcoin-ml <
bitcoin-ml at lists.linuxfoundation.org>:

> Dear Bitcoin Cash community,
>
> Bitcoin Cash has been in need for a new address format for quite some
> time. There is an immediate problem as people mistakenly send BCH to BTC
> address and vice versa, which is made worse by the fact that segwit on the
> BTC chain had the brilliant idea to leverage outputs that anyone can spend,
> which make the recovery of the funds delicate on the Bitcoin Cash chain.
>
> Because this need is pressing, companies like Bitpay started using
> incompatible addresses format and this is causing fragmentation in the
> Bitcoin Cash ecosystem. I do not wish to blame Bitpay, they took action to
> solve the problem their business faces, this is good business from their
> part.
>
> However, while the problem of funds sent on the wrong chain is pressing,
> there are other reasons we need to update the address format. It is
> imperative that the chosen standard for Bitcoin Cash address the various
> issues present with the current address format as we cannot change
> addresses every other tuesday. The most important one being that current
> outputs are using 160 bits hashes for multiparty contracts such as
> multisig, which is really playing with the limit of what can be considered
> secure. It is also desirable that the format chosen can accommodate new
> features we wish to deploy, or, in other terms, be extensible.
>
> As a result, I propose to upgrade to the cashaddr format. This format (
> https://github.com/Bitcoin-UAHF/spec/blob/master/cashaddr.md ) is based
> on work from Rusty Russel ( https://rusty.ozlabs.org/?p=578 ) and uses
> BCH codes in order to ensure error detection as suggested by Pieter Wuille
> for bech32.
>
> Using a new format will prevent users from mistakenly sending money on the
> wrong chain. It also accept payloads up to 512 bits which ensures we can
> deploy more secure way of doing multiparty smart contract in the future.
> Finally, it uses a version field ensuring we can encode new features in
> these addresses in the future without having to use a new format.
>
> In addition of these must have features, cashaddr improve on several
> aspects of current address format in a way that may not justify in itself
> to use a new format, but are nevertheless really nice to have.
>  - It uses a very strong checksum which ensure detection of up to 6 errors
> in an address and 8 in ‘burst’. Larger number of errors have one chance
> over a thousand billion to lead to a valid address.
>  - It encode more compactly in QR codes as it allows the use of the
> alphanumeric mode.
>  - It is much faster to encode and decode than the previous format, which
> is important for system having to handle a large number of addresses.
>
> In order to reduce confusion for users with the use of different
> addresses, I think it is important to deploy this shortly and stop the
> fragmentation of the ecosystem. Deploying such a change on the network will
> take some time for all wallet, exchanges and merchant to upgrade. Christmas
> and new year is coming soon and nobody want to do such an upgrade during
> this time. As a result, I propose we aim for a deployment around Jan, 14 .
> This leaves 2 month for everybody to get ready which I think is reasonable.
> Delaying further would push us into the Chinese new year territory, which
> is also undesirable.
>
> The next version of Bitcoin ABC will include support for cashaddr, hidden
> behind a configuration at first, so people can experiment with it. I would
> like to invite via this message various participants in the ecosystem to do
> the same.
>
> Let's do it ?
>
> Amaury Séchet
>
> _______________________________________________
> bitcoin-ml mailing list
> bitcoin-ml at lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-ml
>
>


-- 
Lucas Clemente Vella
lvella at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linuxfoundation.org/pipermail/bitcoin-ml/attachments/20171115/2426c14d/attachment-0001.html>


More information about the bitcoin-ml mailing list