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From: Andy Parkins <andyparkins@gmail.com>
To: bitcoin-development@lists.sourceforge.net
Date: Mon, 30 Jan 2012 10:57:54 +0000
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Subject: Re: [Bitcoin-development] BIP-12, 16, 17
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On 2012 January 28 Saturday, Michael Gronager wrote:

> If we want more information in a bitcoin address we could just as well
> cannibalize it from the checksum - today it is 4 bytes (1 to 4mia) it
> could be 2 or 3 bytes (1 to 65k or 16M) and that would not break the
> current meaning of the network ID. This would have the same effect - that
> you could not mistake two different addresses and create a non-redeemable
> transaction.

I'm throwing this out as an idea; not necessarily saying it's doable or eve=
n=20
good.

There is spare capacity in the base58 encoding.

 - The address hash is 20 bytes
 - The checksum is 4 bytes
 - The address type is 1 byte
=20
The longest and largest address is therefore 25 bytes of 0xff (it's not=20
possible to all be 0xff of course).  Converting those 25 bytes of 0xff to=20
base58...

 hex:    ffffffffffffffffffffffffffffffffffffffffffffffffff
 base58: 2mXR4oJkmBdJMxhBGQGb96gQ88xUzxLFyG

This is 34 base58 symbols.  It's not the largest base 58 number that will f=
it=20
in 34 symbols though...

 base58: zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
 hex:    20a8469deca6b5a6d367cbc0907d07e6a5584778de27ffffffff
 vs hex:   ffffffffffffffffffffffffffffffffffffffffffffffffff

i.e. there are a few unused bits (~5) available in the base58 representatio=
n=20
that can be added without changing the number of symbols in the address.


Andy

=2D-=20
Dr Andy Parkins
andyparkins@gmail.com

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