20091029, 06:50  #1 
Oct 2009
3^{2}×7 Posts 
A strange RSA key
Finally С154 job is done:
78M relations collected, from 0 to 35M 39M Unique relations Three prp found, prp24,prp96,prp34 It tooks about a week totally. 1 np 4 days sieving 4 Dual Xeons 1 day matrix solving 12 hours square Last fiddled with by siew on 20091029 at 07:27 
20091029, 08:06  #2  
Nov 2008
2×3^{3}×43 Posts 
Quote:
If it isn't a proper RSA key, you must do ECM first. Then you would have probably found the p24 in 12 minutes, and the p34 in 12 hours. 

20091029, 08:07  #3 
Feb 2005
The Netherlands
2·109 Posts 
prp24 and prp34? Didn't you do some ECM before sieving? Could have save you about a week...
Last fiddled with by BigBrother on 20091029 at 08:07 
20091029, 08:09  #4 
Jul 2006
Calgary
5^{2}×17 Posts 
Do you think the key generator might have somehow mistakenly considered p24 times p34 as a probable prime?

20091029, 08:13  #5  
Nov 2008
2×3^{3}×43 Posts 
Quote:
Earlier in the thread, siew wrote: Quote:
Actually, I'm surprised I didn't catch that as a lie early on: if it is a real RSA key used for signing real code, then it has to be better than 512 bits nowadays. Last fiddled with by 10metreh on 20091029 at 08:14 

20091029, 08:48  #6 
Oct 2009
3^{2}×7 Posts 
Please, that was my first big factorization, so what do you mean "ECM before"?

20091029, 09:01  #7 
Jul 2006
Calgary
5^{2}·17 Posts 

20091029, 09:37  #8 
(loop (#_fork))
Feb 2006
Cambridge, England
13×491 Posts 
The problem is that, if you know the key is an RSA number, 'ECM before' is extremely bad advice; it's absolutely guaranteed to waste time.
The crucial question: does the private key you obtain from the factorisation allow you to sign code that works? If so then the encryption system is very peculiar; if not, then maybe the number's in the wrong byte order or has an implicit leading bit or something? 
20091029, 12:08  #9 
Tribal Bullet
Oct 2004
6720_{8} Posts 
fivemack is right, the most likely explanation is that the string of bits you think is an RSA key needs to be byteswapped or something.

20091029, 12:15  #10 
Oct 2004
Austria
2×17×73 Posts 
Hmmm... maybe one should spend a few hours (not more!) of ECM and P1 even on RSA keys to see if things like that have happened?

20091029, 13:19  #11 
Oct 2009
3^{2}·7 Posts 
Will try to ECM too :) tanx.
And what about 3 prp ? It it possible , that original key generator used 3 primes, not 2 ? p,q ? 
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