Electronic money

Charles Lindsey chl at clerew.man.ac.uk
Sun Dec 7 14:56:30 GMT 2014

On Sun, 07 Dec 2014 10:45:43 -0000, Ben Laurie <ben at links.org> wrote:

> On Sun Dec 07 2014 at 10:21:35 AM Charles Lindsey <chl at clerew.man.ac.uk>
> wrote:
>> On Fri, 05 Dec 2014 20:47:42 -0000, Ben Laurie <ben at links.org> wrote:
>> > Consider the following thought experiment. I am an Evil Genius, with a
>> > Lot
>> > of Computers.
>> >
>> > I go away for a year and mine bitcoins on my own version of the chain.
>> > Because I have a LoC, I can do this faster than the rest of you.
>> >
>> > When the year ends, I present my longer chain, and under the Holy  
>> Rules
>> > of
>> > Bitcoin, all of the last year of mining and transactions goes away.
>> >
>> > Clearly this situation is untenable. The solution? Checkpoints.
>> >
>> > Those who set the checkpoints are the central authority.
>> AIUI, if you mine a bitcoin (and coincidentally someone else mines the
>> same one), then the first to register it in the Ledger takes preference
>> (AFAIK, the mineable bitcoins have no predefined order).
> Clearly you don't understand it: longest chain wins.

Maybe not, but then I suspect neither do you.
> Also, what is this "the" Ledger you register first in?

The Ledger is officially known as the Block Chain. AIUI when you discover  
a new Bitcoin, you add it to the block chain (after which you can spend  
it, such transaction also being recorded in the chain). If somebody else  
discovers the same Bitcoin, it cannot be added to the chain, since it is  
already there.
>> Anyway, it is all
>> described in Wikipedia, and I don't think your situation would cause any
>> problem.

And the Wikipedia article indeed describes your attack, but apparently  
there are flaws in your argument and the consensus appear to be that the  
risk is nonexistent.
> Uhuh.

Charles H. Lindsey ---------At Home, doing my own  
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Email: chl at clerew.man.ac.uk      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU,  
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