VIFF

Hi Mikkel, It seems that the type of l is determined by the one of the security parameter. How do you set it? I can't find a statement that would set it to a float under any circumstances. The OverflowError is not shown because it is wrapped and ... [More] given to the errback of a Deferred, which usually is the normal callback, which in turn might result in a frozen program. That makes debugging quite annoying, but it can only be avoided by either changing the Twisted code or by defining an appropriate errback for every Deferred/Share object. I would rather make sure that the security parameter always is an integer, otherwise the same error could happen somewhere else. Best regards, Marcel [Less]

Hello, I posted a while ago that comparison doesn't work above a certain bitlength (969 bits to be exact). I've found out why. The following is called: rand.randint(0, (2**l) - 1) The value for l is somehow made into a float (in this case 1031.0). ... [More] This works well for small values of l, but at some point it gives you an OverflowError that is hidden from the user. Just looks like the program is frozen. Shouldn't the error be shown? It works if you insert l = int(l) before the statement above. Obviously it needs to not be a float in the first place. I'd be happy to send in a patch for this if I could remember how that works. In any case, now you know. I can also say that I've tested it with 2000 bit numbers, and although it's not fast, at least now it works for huge numbers as well. Regards, Mikkel Krøigård [Less]

The current implementation of the Orlandi runtime found in orlandi.py unfortunately depends on a 3rd party party package for elliptic curve cryptography that is not open source. So unless you have a special agreement with the owners of that package ... [More] (http://www.cryptomathic.com) or can find something similar, you won't be able to use it. The BeDOZa runtime is completely open-source, but as Claudio mentions, it is not fully implemented yet. So for now, the only 2-party runtime is the passively secure paillier runtime in paillier.py. Regards, Thomas [Less]

There is also an Orlandi runtime and a BeDOZa runtime (under development). They work for 2 parties and guarantee security against active adversaries (paillier.py is only for passive security). Claudio 2010/10/7 Mikkel Krøigård <mk< at >cs.au.dk>:

Citat af Kyung-Wook Hwang <kwhwang< at >ee.columbia.edu>: That depends on the runtime you use. If you are using the default passive security runtime, this is based on Shamir secret-sharing. Therefore there must be at least 3 ... [More] parties, and the threshold will always be < n/2. There is in fact also a two-party runtime based on the Paillier cryptosystem. You can check it out if you want, it's in paillier.py. But basically you have to select a runtime that gives you what you want. If you want 2-party MPC, you can't use the Shamir sharing based runtime. As you can see, it's using shamir_share. Shamir sharing requires at least 3 players. Same as above :) Regards, Mikkel Krøigård _______________________________________________ viff-devel mailing list (http://viff.dk/) viff-devel< at >viff.dk http://lists.viff.dk/listinfo.cgi/viff-devel-viff.dk [Less]

Hello, This is Kyung Hwang from Columbia University again. I have another question. Does Viff always need at least 3 participants? It seems to me it does. I modified "beginner.py" for two players because that file was simplest to modify, but when ... [More] I ran the two players, I got the following errors: kwhwang< at >kwhwang-sim1:~/viff-1.0/apps$ python beginner2.py player-2.ini 20 --no-ssl Seeding random generator with random seed 3781 /home/kwhwang/opt/lib/python/viff/prss.py:43: DeprecationWarning: the sha module is deprecated; use the hashlib module instead import sha I am player 2 and will input 20 Not using SSL Listening on port 9002 #### Starting reactor ### ---------------------------------------------------------------- Program started Error: [Failure instance: Traceback: <type 'exceptions.KeyError'>: 3 /home/kwhwang/opt/lib/python/viff/runtime.py:317:stringReceived /home/kwhwang/opt/lib/python/viff/runtime.py:456:identify_peer /usr/lib/python2.6/dist-packages/twisted/internet/defer.py:280:callback /usr/lib/python2.6/dist-packages/twisted/internet/defer.py:354:_startRunCallbacks --- <exception caught here> --- /usr/lib/python2.6/dist-packages/twisted/internet/defer.py:371:_runCallbacks beginner2.py:69:protocol /home/kwhwang/opt/lib/python/viff/passive.py:493:input /home/kwhwang/opt/lib/python/viff/passive.py:550:shamir_share /home/kwhwang/opt/lib/python/viff/runtime.py:785:_expect_share /home/kwhwang/opt/lib/python/viff/runtime.py:749:_expect_data /home/kwhwang/opt/lib/python/viff/runtime.py:754:_expect_data_with_pc I also modified equality.py for two players to see if it works for only two players because that file actually compared only two players' inputs but not the third player's so that file essentially needs two players. But it gaves errors too with two players. I think Viff only works with at least three players. Am I correct? Thank you. Kyung [Less]

Hello, We've been trying to run an MPC LP solver (by Tomas Toft) for a while now and can't get it to work for examples of a more realistic size. One problem we're having right now is that using the Toft07 comparison, we can basically get VIFF ... [More] to drop to 0% CPU usage and just sit there forever. What we did was run the "compare.py" test program from viff/apps but with Toft07 instead of Toft05, and with different bit lengths. Running it with anything up to and including 968 seems to work. 969 and beyond apparently makes VIFF freeze. If anyone has any ideas or can tell us what exactly we're doing wrong, it would be much appreciated. [Less]