Re: [viff-devel] Equality protocol : error

2010-04-19 Thread Marcel Keller
Hi Jonathan, thanks for sending the config files. I could reproduce the error using them. It turned out that the equality module doesn't handle the case of the masked value c being zero. The latest code on viff.dk is now fixed. Best regards, Marcel Jonathan Van den Schrieck wrote: Dear Mr. K

Re: [viff-devel] Equality protocol : error

2010-04-12 Thread Jonathan Van den Schrieck
Yes, indeed. Nice guess :-). Jonathan Le 10 avr. 2010 à 23:19, Sigurd Torkel Meldgaard a écrit : >> Thank you for your idea wich is very helpful to me since I actually work >> with p = 53. >> Using this is much more efficient ! > > Might I guess you are implementing a card game? ; ) > > - Sig

Re: [viff-devel] Equality protocol : error

2010-04-10 Thread Sigurd Torkel Meldgaard
> Thank you for your idea wich is very helpful to me since I actually work with > p = 53. > Using this is much more efficient ! Might I guess you are implementing a card game? ; ) - Sigurd ___ viff-devel mailing list (http://viff.dk/) viff-devel@viff.d

Re: [viff-devel] Equality protocol : error

2010-04-10 Thread Jonathan Van den Schrieck
ok, my problem is solved, the error came from the config files. I generated new ones and the error was gone. I would like to thank everyone for their help in finding the solution, especially Mr. Keller. Jonathan Le 8 avr. 2010 à 23:34, Marcel Keller a écrit : > Hi Jonathan, > > I can't reprod

Re: [viff-devel] Equality protocol : error

2010-04-10 Thread Jonathan Van den Schrieck
Dear Mr. Meldgaard, Thank you for your idea wich is very helpful to me since I actually work with p = 53. Using this is much more efficient ! Regards, Jonathan Le 9 avr. 2010 à 01:10, Sigurd Torkel Meldgaard a écrit : > I know this is talking around the problem but: > > For very small moduli

Re: [viff-devel] Equality protocol : error

2010-04-08 Thread Sigurd Torkel Meldgaard
I know this is talking around the problem but: For very small moduli like yours, another protocol for equality is actually simpler, better (no risk of failing) and faster (I guess): raise (a-b) to n-1 (with square and multiply), and if this difference was 0 you will get 0, otherwise you will get

Re: [viff-devel] Equality protocol : error

2010-04-08 Thread Marcel Keller
Hi Jonathan, I can't reproduce the error here. Can you send me your config files? The error might be triggered by certain random numbers, which depend on the PRSS keys. By the way, the error message is about the same every time something goes wrong in a callback. This is because VIFF does no

Re: [viff-devel] Equality protocol : error

2010-04-08 Thread Jonathan Van den Schrieck
Dear Ivan, Yes I know about that. But 367 is 3 mod 4 so it should be OK. And the existing protocol works with 367 only if the two numbers are not equal. If they are, I got the error mentioned in my first message. If I can solve the error in the existing protocol, I will be able to continue my w

Re: [viff-devel] Equality protocol : error

2010-04-08 Thread Ivan Damgård
Dear Jonathan, You cannot expect the protocol to work for primes that are 1 mod 4, it is based on the fact that for primes p that are 3 mod 4, you can deterministically compute a square root mod p by raising to power (p+1)/4. This does not work if p is 1 mod 4. regards, Ivan On 08/04/2010, a

[viff-devel] Equality protocol : error

2010-04-08 Thread Jonathan Van den Schrieck
Hello, I am trying to modify the equality protocol to make it work for primes congruent to 5 mod 8 (exists for Blum primes). The problem is that I have an error with the original protocol. It works perfectly with p = 211 for example. But for p = 367, it doesn't. Here is the code I'm using to tes