I have read the history of the RSA-129 challenge, and now I would like to know if it would be possible to factor RSA-129 with a single "average" personal computer, today. Has someone tried to do this particular factoring?


1 Answer 1


From what I can gather it took about 2.5 months to factor a 512 bit RSA key on a personal computer from 2009 with a dual-core athlon64.


A typical desktop of today has about twice as many cores and twice the clockspeed. So that would cut it down to about two and a half weeks.

Furthermore modern processors have better IPC and your key is less than 512 bits.

So clearly doable but probablly not instant.

  • 2
    $\begingroup$ Just to be precise, the RSA-129 challenge was 426 bits. $\endgroup$
    – mikeazo
    Mar 14, 2018 at 23:16
  • 4
    $\begingroup$ The CADO-NFS website specifies 107 CPU hours for factoring RSA-130, so with a handful of cores this is clearly doable in less than a day. $\endgroup$
    – yyyyyyy
    Mar 14, 2018 at 23:39
  • $\begingroup$ I have tried CADO-NFS, but at the start of the sieving phase, after one day of computation, it crashes. I have tried with the latest release, and also with the stable version. $\endgroup$
    – zar
    Mar 18, 2018 at 15:50

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