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[solved] Challenge "RSA Factoring Challenge: RSA-704"  

  By: admin on Feb. 7, 2012, 10:40 a.m.

This challenge descends from the RSA Laboratories contest to encourage research into the practical difficulty of factoring large integers of different length (between 330 and 2048 bit) and cracking RSA keys used in cryptography. This challenge is about factoring a number with 212 decimal digits.
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 Last edited by: admin on Oct. 31, 2021, 2:55 a.m., edited 2 times in total.

Re: Challenge  

  By: Veselovský on Sept. 26, 2012, 3:18 p.m.

This number was already factored in July 2, 2012.
http://en.wikipedia.org/wiki/RSA_numbers#RSA-704
So it is time to remove this challenge.

Admin should check the code for verifying the solution because none of the correct factors of the number N was accepted, as I checked. It probably is the same with all of RSA Factoring Challenges.

Re: Challenge  

  By: Veselovský on Sept. 26, 2012, 3:36 p.m.

By the way… these RSA Factoring Challenge which are in level 2 are underrated.

If we look at the report of this factorization:
http://maths.anu.edu.au/~bai/paper/rsa704.pdf

We can read:
"Polynomial selection started end of April 2011."
"The total time spent in polynomial selection was about 12 core years (about 2.2 for degree 5, and 9.9 for degree 6), using about 100 cores at ANU."
"The last phase (mksol) started on June 13 and ended on June 29, 2012"

…more than a year

Their time spend on it and all the hardware used is far beyond the level 2, isn't it?

Re: Challenge  

  By: be on Sept. 26, 2012, 8:39 p.m.

  • Admin should check the code for verifying the solution
  • By the way… these RSA Factoring Challenge which are in level 2 are underrated.

Thanks a lot for the information. We really appreciate your feedback. We will check this.

Re: Challenge  

  By: Prestige on Oct. 24, 2012, 10:03 p.m.

Sorry for my late reply, we took RSA-704 offline, because our system does not yet support solving challenges where the solution is publicly known (this is in the making though).

Thank you for your notification. We will publish RSA-704 again once we have a system that can handle challenges that give zero points or are unsolvable.

Challenge RSA-704  

  By: Theofanidis on July 25, 2013, 7:45 a.m.

Dear MTC3 team

Since everything else is excellent, i would like to point out a minor problem.

Although the Level-III challenge RSA-704 is offline and it is not displayed any more it is still added as a challenge.
Specifically when one uses the menu My Profile and then Challenge Overview under the Total progress the percentage is wrong i.e. 62/157 = 39.49%
the correct one should be i.e. 62/156 = 39.74%

because total Challenges are
Level 1 51
Level 2 52
Level 3 42
Level X 11
Total 156 and not 157

Best regards
George Theofanidis

P.S. The reason to report this minor problem is not to correct the percentage - the increase is very small - but to identify the problem because if later other challenges would be offline they would be present while they should not be.

Re: Challenge RSA-704  

  By: be on July 25, 2013, 11:02 p.m.

The reason to report this minor problem is not to correct the percentage - the increase is very small - but to identify the problem because if later other challenges would be offline they would be present while they should not be.

Hello George, you are completely right. We have to fix this. We put this on our todo list and come back, when it is fixed. Thanks, BE

Re: Challenge  

  By: Javex on July 29, 2013, 9:59 a.m.

Hello George,

We have looked into this problem. It is already fixed in our current development version. Once the next update is through (within the next three weeks), all numbers should be correct again.

Regards,
javex

Re: [solved] Challenge  

  By: andru183 on Sept. 25, 2013, 4:04 p.m.

Hi guys, I'm very new to cryptography and hope someone could help me with a noob question. I don't expect this to be spelled out to me and am happy to research myself, but I just don't understand how to do questions like this other than brute force. Is there anyone kind enough to point me to something to find an intelligent way to solve these kinds of questions please? Or is it pretty much brute force all the way?

Re: [solved] Challenge  

  By: be on Oct. 3, 2013, 9:03 p.m.

I'm very new to cryptography and hope someone could help me with a noob question. I don't expect this to be spelled out to me and am happy to research myself, but I just don't understand how to do questions like this other than brute force. Is there anyone kind enough to point me to something to find an intelligent way to solve these kinds of questions please? Or is it pretty much brute force all the way?

Hello andru,
The RSA challenges deal with factorizing big compound numbers.
For numbers consisting only of two big factors there are much better algorithms than doing brute-force division of all primes smaller than the square of the number.
Samples are the algorithms Pollard-Rho, Pollard-p+1, the quadratic sieve, or the general number field sieve. These algorithms differ in their performance and their pre-requsites. A good sample of the differences with different numbers can be found in the online help of CrypTool 1 – see "Dialog Factorization of a Number". There are also several books about this topic, like:

Re: [solved] Challenge  

  By: fmoraes on July 2, 2014, 1:11 a.m.

Is there something wrong with the checking of the answer on this challenge? The official numbers don't seem to be accepted.

Re: [solved] Challenge  

  By: aurelie on July 6, 2014, 4:50 p.m.

Is there something wrong with the checking of the answer on this challenge? The official numbers don't seem to be accepted.

Hello fmoraes,

I checked the solutions that you have submitted and compared it to solutions that have been accepted in the past and with the official numbers. It seems like you're right because the first prime you've submitted on July 2nd was correct and another user has successfully submitted this number in June.

I'm going to forward your problem to the one in charge in our team and keep you updated!


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