[RC5] Did the calculations again...

Richard Farmbrough rawkiw at cix.co.uk
Wed Jan 7 04:37:47 EST 2004

Some time ago calculations were done to the effect that it was more 
productive to solve hard problems by waiting until they could be completed 
in 18 months before starting.
This was based on buying hardware of course. However a similar 
consideration may apply to other costs, such as power and soicla costs of 
running a 17 year project.
The challenge for this type of organisation is finding problems of the 
right level of computational difiiculty, programming simplicity and general 

-----Original Message-----
From:	Elektron [SMTP:elektron_rc5 at yahoo.ca]
Sent:	07 January 2004 06:26
To:	D.net Discussion
Subject:	Re: [RC5] Did the calculations again...

On 7 Jan, 2004, at 05:41, Daniel Quintiliani wrote:

> 163536894738 Keys/s produces
> k = 5.160831909 * 10^18


First, it shows that the average keyrate now is closer to 130 G (it may
be more like 120, because I tink the recent peaks are due to the
downtime in stats or something).

It also shows that keyrate doesn't increase exponentially with time
(not yet anyway).

> Our formula is:
> t = ln(2^72/((5.160831909 * 10^18) ln(2^(1/1.5)))) / ln(2^(1/1.5))
> That comes to 16.42712929 years (16 years, beginning of June) for all
> of the keys to be finished (from 399 days ago). That's a 9 month
> reduction from a calculation three months ago! We may finish much
> sooner than we all think, especially since we usually find the key
> before we reach 100%.
> Now I see what you mean about new participants. We should add that to
> the stats - when 100% will be reached if Moore's Law holds true during
> that time if no new participants join. (We currently only have those
> stats *without* calculating Moore's Law.) Check my math once more and
> I'll submit an enhancement request.

Apparently the old calculation gave 17.20178906 years

With 160 Gkeys/s, I get 16.92378607786446985959.

With 2^72*(1-0.00068) total keys (because .068% is done), I get

That's a difference of 0.00147204949527740501 years, or
12.90398587560173231766 hours.

So all the work on RC5-72 so far amounts to half a day (of course, this
is because the extra keys, in 16 years' time, would take half a day to

- Purr


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