Hello ZmnSCPxj,
ZmnSCPxj wrote on 8/16/21 5:34 AM:
Good morning TS,
Entering a BTC address for a transaction can pose a risk of error (human or
technical). While
there is a checksum integrated in BTC addresses already, this is used only at a
technical
level and does not avoid entering a valid but otherwise wrong address.
Moreover, it does not
improve the overall user experience.
In case this hasn't been discussed before, I propose to implement a 3 or 4
digit code (lets
call it 4DC for this text), generated as checksum from the address. This 4DC
should be shown
in all wallets next to the receiving address. When entering a new address to
send BTC, the
sending wallet should also show the 4DC next to the entered address. This way,
the sending
person can easily verify that the resulting 4DC matches the one from the
receiving address.
This would mean that a receiver would not only send his public address to the
sender, but also
the 4DC. A minor disadvantage since a) it is not mandatory and b) it is very
easy to do.
However, it would greatly reduce the probability of performing transactions to
a wrong address.
Technically, this is very easy to implement. The only effort needed is agreeing
on a checksum
standard to generate the code. Once the standard is established, all wallet and
exchange
developers can start implementing this.
Thanks for your comments.
I think the "only" effort here is going to be the main bulk of the effort, and it will
still take years of agreement (or sipa doing it, because every review is "either sipa made it,
or we have to check *everything* in detail for several months to make sure it is correct").
I understand. If sipa could do it that would greatly simplify the process. Once an algorithm
for the generation of the code exists, it just needs to be communicated to wallet developers
and let it grow organically. No need of extensive testing, since it is only a very simple
function.
In any case --- the last 5 characters of a bech32 string are already a
human-readable 5-digit code, with fairly good properties, why is it not usable
for this case?
Well, because
a) most people don't know that
b) it is specific to bech32
c) it is not easily readable being the last digits of a long address (although this could be
fixed by the wallet by showing those digits bigger or separately)
d) and most importantly: as mentioned in above my proposal, it only proves that an address is
valid, but not necessarily the correct one (perhaps the user copied the wrong address, there
was an old address in the clipboard, etc.)
On the other side of the coin, if you say "the existing bech32 checksum is
automatically checked by the software", why is forcing something to be manually
checked by a human better than leaving the checking to software?
Not better, it should be on top. And not forced, but just as an optional check for the user.
The SW can (and should) only check that the address is valid (the SW doesn't know the user's
intent). Only the human can "double-check" an easy-to-read-code to quickly know that he is
doing the right thing. (Entering a valid but wrong address is even worse than entering an
invalid one, since the latter will be stopped by the wallet. But the former most likely
results in loosing the funds.)
Note: The code should never be entered manually or even copied together with the address in
one string. From the SW point of view, the code is an output only, never an input. It is
merely a visual verification for the user.
Example of use: person A calls via phone person B and says: "Send me 0.1 BTC to my address I
just sent you via whatsapp. When entering the address, make sure that you get the verification
code 4385."
Regards,
TS
Regards,
ZmnSCPxj
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