[RC5] What if RC5-64 is done

Tom Ribbens webmaster at multi-air.com
Sat Jun 2 11:59:00 EDT 2001

```Richard Menedetter wrote:
>
> Hi
>
> 01 Jun 2001, Tom Ribbens <webmaster at multi-air.com> wrote:
>
>  TR> i was wondering how long it would take before RC5-72 work units will
>  TR> be distributed.
> Will they be distributed ?? don't think so !
>
>  TR> I mean, imagine that we find the RC5-64 key tomorrow,
>  TR> when will the master keyserver be handing out new RC5-72 blocks?
>  TR> Or is distributed.net not going to participate in that contest?
> I haven't heared of it.
>
> but think of it:
> 72-64=8 bits
> 2^8=256
>
> So RC5-72 will be 256 times harder than rc5-64.
>
> It will take us over 3.5 years to reach 50% of rc5-64.
> 3.5*256=896 years

BUT: At the beginning of RC5-64 the time remaining with that keyrate was
also 1235 years
you are now saying that it would take 1792 years at this keyrate to
exhaust RC5-72 keyspace
that is an increase of 145%
days worked at RC5-64 + estimated days left at this keyrate = 1886 days

Then for RC5-72
1886 * 145% = 2735 days
2735 / 365 = 7.5 years

7.5 years is still doable in my opinion.

Tom

>
> If the computer's crunching power increases by a factor of 8, we would only
> need 112 years ...
>
> (PS: if we are unlucky it could take twice as long. If we only find the
> winning key at 99.9%)
>
> Wait till I have bought my AMD K16 with 850 THz or my quantum computer !
>
>  TR> Tom Ribbens
>
> CU, Ricsi
>
> --
> |~)o _ _o  Richard Menedetter <ricsi at bigfoot.com> {ICQ: 7659421} (PGP)
> |~\|(__\|  -=> Our first and last love is - self-love <=-
> --
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