[Bitcoin-development] Bitcoin addresses -- opaque or not

Pieter Wuille pieter.wuille at gmail.com
Tue Jun 11 14:12:52 UTC 2013

On Tue, Jun 11, 2013 at 3:11 PM, Melvin Carvalho
<melvincarvalho at gmail.com> wrote:
> There was some confusion on IRC as to whether bitcoin addresses are opaque
> or not.
> https://en.bitcoin.it/wiki/Address
> For the sake of argument let's say that opaque means that you can tell
> nothing about the address by examining the characters.
> My understanding was that they are NOT opaque, and that if that has changed,
> it will invalidate much at least some wiki page, for examples at least some
> of the following would now be false:

I'm afraid this is the result of a misunderstanding.

Yesterday on IRC you were asking why the URI specification doesn't
include the semantics and encoding of addresses. Some people,
including me, argued that addresses should be considered opaque. That
doesn't mean they don't have well-specified definition, only that for
the purposes of URI parsing and handling, code shouldn't know or care
what they represent or how they are formatted. Addresses are specified
in one place, and the URI format simply passes addresses through.

The reason for keeping them independent is that the address format
could change (say, a new type is added, like P2SH (BIP13) before), and
there is no reason why this should break or even concern URI handling
code. Clearly, anything that actually interprets addresses in order to
construct transactions will need changing. It's just two separate
concerns, and they should be dealt with separately.


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