[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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