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Re: Challenge  

  By: Javex on Feb. 9, 2012, 3:33 p.m.

We had a problem at the PHP server checking the solution. This is fixed now. The elapsed time runs from now on, so you again have the chance to get 2000 points for the first day.

Also do not worry: All your trials have been reset and you can have a fresh start.

You should now be able to solve the Challenge (the correct solution is now in the system and is confirmed). We are now working on clarifing the input in our TeX-Files.

Re: Challenge  

  By: Veselovský on Feb. 9, 2012, 3:53 p.m.

I do not see any changes. None of the formats of d', that I tried to submit again, was accepted.

Re: Challenge  

  By: Witten on Feb. 9, 2012, 4:10 p.m.

same for me, tried both the 1023 format and just the exact 510 bits, nothing…

Re: Challenge  

  By: Veselovský on Feb. 9, 2012, 4:11 p.m.

I have to say again. This is quote from PDF:

There are two possible solutions for d' we are searching for the greater number.

This is not true. There are plenty of d' that have same first 510 bits as it has d.
We can determine the lower bound "dl" and upper bound "du" of d satisfying dl<=d<=du. All these d in this interval have same first 510 bits. You can not say that one of them is better approximation than the other unless you know exact value of d.
So again, do we have to submit 1023 bits or 510 bits of d?

Re: Challenge  

  By: Bart13 on Feb. 9, 2012, 8:16 p.m.

Lets face it guys: we've all been beaten by the fairer sex.

Re: Challenge  

  By: Veselovský on Feb. 9, 2012, 8:27 p.m.

I do not think so… Javex also "solved" the challenge. But the question is if their wanted answer is really a correct one. Either they made mistake or they used a different N for computation as is written in PDF. I also made my own N with known p, q and d and was able correctly find the 510 bits of d, so my method is correct.

Re: Challenge  

  By: Bart13 on Feb. 9, 2012, 9:10 p.m.

Perhaps the missing digit in N does pose a problem, but that would mean that N is 1027 bits which can not be with p and q having 512 bits.

Re: Challenge  

  By: Veselovský on Feb. 9, 2012, 11:16 p.m.

Be patient. Do not try to solve this challenge for now, they will soon clarify it for us again.

Re: Challenge  

  By: Javex on Feb. 10, 2012, 9:18 a.m.

Since it seems this one isn't clear right now, we will try a different approach and make the challenge dynamically verified. I will hopefully have done that by the end of the day. Again, I will make sure no one has any disadvantages by this.

P.S.: Do not worry, if either me, aurelie, be, admin or maybe some other admin user solve a Challenge, we only did that to test it live. All those solvents did have the solution form the start and I will remove these names from the HoF.

Re: Challenge  

  By: Javex on Feb. 11, 2012, 1:21 p.m.

Hello everyone,

I just finished repairing the challenge and you should now be able to input any correct solution.

Keep in mind: Your input has to be of length 1022 - 1024 bit, not 510 bit. The truncation will be done by the server which will only compare the 510 most significant bit.

The PDFs have been updated to clarify the new version.

Re: Challenge  

  By: Bart13 on Feb. 11, 2012, 1:35 p.m.

@Javex:

Thank you very much for all your efforts and for sacrificing a free Saturday !
Using only the 510 most significant bits is the right way to determine if someone has found the correct solution.
But somehow there must have been an error in the original solution as we've all tried all possible binary values for d': 510 bits, 1023 bits, 1024 bits, and they were all wrong.

The work is not finished however…:)

Currently I'm listed first which is not correct.
I'm pretty sure Veselovsky solved it first and others were ahead of me as well.
So I'm only 3rd or 4th as I can see it from all the posts about this challenge.

Also there is the matter of awarded points.
No need to resolve this over the weekend.

Thanks again!

Re: Challenge  

  By: Javex on Feb. 12, 2012, 5:22 p.m.

Currently I'm listed first which is not correct.
I'm pretty sure Veselovsky solved it first and others were ahead of me as well.
So I'm only 3rd or 4th as I can see it from all the posts about this challenge.

Also there is the matter of awarded points.
No need to resolve this over the weekend.

Thanks again!

Our Logs clearly show that you were the first to submit a solution (13:23) with Veselovsky following quick at 13:32. Of course this was just a matter of who read my post first, since you clearly all had the solution.
I am sorry that you didn't get a proper race here.

Thanks for noting the incorrect time, I forgot this upon updating this challenge. Now you have correctly earned 2000 points.

If any further issues arise, please let me know.

Re: Challenge  

  By: Etschupu on July 10, 2012, 2:51 p.m.

Hello,

since i have already used several of my trails (3 left) and i am pretty sure to have the correct solution, i wanted to ask if someone could help me how to enter the exact solution?

  1. In which order to i have to insert the solution MSB first or LSB first?
  2. One hint says "There are two possible solutions for d', we are searching for the greater number." I guess, there are MUCH more integers for d' since i thought only the first 510 bit matter? Or whats up with this hint?

Thx,
Etsch

Re: Challenge  

  By: be on July 25, 2012, 3:53 a.m.

i am pretty sure to have the correct solution, i wanted to ask if someone could help me how to enter the exact solution?

  1. In which order to i have to insert the solution MSB first or LSB first?
  2. One hint says "There are two possible solutions for d', we are searching for the greater number." I guess, there are MUCH more integers for d' since i thought only the first 510 bit matter?[/quote:2hkpi4oy]Hello Etsch,
    -> 1) MSB (so you were correct).
    -> 2) There are at least 2 possible solutions which have the correct first 510 bits.

We check the first 510 bits, and whether the overall length is appropriate. So I saw, that the last solution from you ([14]) was correct in the first 509 bits, but the 510th bit was wrong.
Does this help? If you need more hints, please send me an email.

Re: Challenge  

  By: Bart13 on July 28, 2012, 12:27 p.m.

… but the 510th bit was wrong.
Does this help?

Ha, ha, if the 510th bit was wrong what in the world could it be…..?


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