[Cryptography] Real-world crypto/PRNG problem: Bridge
Viktor Dukhovni
cryptography at dukhovni.org
Tue Aug 23 02:24:13 EDT 2016
On Mon, Aug 22, 2016 at 06:17:31PM -0700, Jon Callas wrote:
> Christian Huitema pointed out to me that 0x5DEECE66D is actually 36 bits
> not 32. I used <http://www.binaryhexconverter.com/hex-to-decimal-converter>
> to convert it to 25214903917,
Which factors to: 7 * 443 * 739 * 11003
$ printf "%d %d * %d * %d * p 16o p\n" 7 443 739 11003 | dc
25214903917
5DEECE66D
> and <http://www.bigprimes.net/primalitytest/>
> reported it to be 7 * 3602129131 (in both hex and decimal) which I verified
> with bc.
$ printf "%d %d * p 16o p\n" 7 3602129131 | dc
25214903917
5DEECE66D
Yes, but the second factor is clearly not a prime. FWIW, I used
http://www.wolframalpha.com/input/?i=factor+25214903917
to do the heavy lifting, presumably it applies ECM, which handles
numbers of this size with no noticeable delay.
--
Viktor.
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