[RC5] 40 bit encryption

Don Cohen cohen at maine.rr.com
Fri Mar 15 16:45:14 EST 2002


On Friday 15 March 2002 09:19 am, you wrote:
> If you assume only one computer
> 1.4*10^9 = 1,400,000,000 cycles per sec
> I think someone said on here recently that the RC5 core takes 250 cycles
> per key.
> so 5,600,000 keys per sec
> 196,341.36210285714285714285714286 sec for key space

Not quit,  you chose 2^40 as the number of keys in forty bit encription 
(which would be a 1 followed by 39 0's).  The correct number of keys is 
2^41 - 1

Divide this by the 5,600,000 k/s you get 392,682.72420554 seconds for keyspace

about 4.5 days.

> about 2 - 3 days.
> Though dnet could do it in less than a second.
>
> Orthanc.
>
>
> ----- Original Message -----
> From: "Brad T." <bradtod at rocketmail.com>
> To: <rc5 at lists.distributed.net>
> Sent: Saturday, March 16, 2002 2:16 AM
> Subject: [RC5] 40 bit encryption
>
> > how long would it take to crack 40bit encryption? Assuming a Athlon TB
> > 1.4ghz computer was used. Some web sites still use this level of
> > security so how safe are they?
> >
> > =====
> > Take care,
> > Check out my site @
> > http://members.tripod.com/~Rambo_21/
> >
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-- 
Don Cohen
cohen at maine.rr.com
http://usmcug.usm.maine.edu/~cohen
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