[hashcash] Re: example v1 stamp
- From: Adam Back <adam@xxxxxxxxxxxxxxx>
- To: hashcash@xxxxxxxxxxxxx
- Date: Thu, 29 Apr 2004 04:26:39 -0400
Kyle wrote:
> I think I have two definitions of "collision" in my head.
>
> 1. The bit collision of the stamp. We generate a collision of X many bits,
> and that's the value of it. When I make a stamp, I'm aiming to produce
> anything that has a certain size collision.
>
> 2. A collision with another generated stamp. That is, two stamps,
> generated independently, that are identical strings.
Correct.
> The stamp has information in it that specifies only the recipient. That's
> fine, but it means that two senders could potentially generate the same
> stamps for that recipient. The senders don't talk to each other, so they
> just have to hope they're unique. If two senders DO produce the same
> stamp, one doesn't go through because we reject double spending.
Yes. So
> I can easily keep from generating stamps identical to ones I generated
> previously. It's harder to keep from colliding with someone else.
Well because we've solved the problem of other people colliding with
you by having 2^64 space per recipient, per day, what I've been doing
is not even trying to avoid my own stamps. ie hashcash client does
not keep track of sent tokens, so it's also possible tho' unlikely for
the same reasons that I could induce a collision on a previous stamp
of my own.
> So, we want to have large random fields so that senders have more space to
> roam around in to avoid hitting each other. Is that what's going on?
Yes.
Adam
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