gmane.comp.cryptography.viff.devel

Re: Security student

Dario Amoruso — 2011-10-17T09:17:34

good morning
the context of reference are Oppnets not collaborative

2011/10/17 Martin Burkhart <martin.burkhart< at >gmail.com>

Re: Security student

Martin Burkhart — 2011-10-17T06:35:48

Hi Dario

The SEPIA library (www.sepia.ee.ethz.ch) is also implemented in Java.
The code is available (LGPL). It supports less-than comparisons, which
is all you need for the Millionaire's problem.

Best
Martin


On 16.10.2011 22:32, Martin Geisler wrote:

Re: Security student

Martin Geisler — 2011-10-16T20:32:24

Hi Dario,

Please reply to the mailinglist, especially if you have followup
questions :-)

As I remember it, the FairPlay system is written in Java, so maybe you
can use this. Perhaps someone else on the mailinglist knows more.

Re: Security student

Martin Geisler — 2011-10-13T10:58:22


Yes, it's implemented:

  http://hg.viff.dk/viff/file/tip/apps/millionaires.py

Please post to the mailinglist (viff-devel< at >viff.dk) instead of me
personally as I'm no longer the maintainer of VIFF.

Re: Error while testing VIFF

shahriar rahman — 2011-08-19T07:55:04

Hi Marcel,

Yeah, the problem was due to cygwin. I have removed cygwin, and reinstalled
everything (python...viff). But some DLL files were missing in system32,
so I had to bring those *.dll files from openssl\bin to system32. Now
everything is working fine.
Thanks a lot for your nice support :)

--Moha

On Thu, Aug 18, 2011 at 11:26 PM, shahriar rahman <mail.jaist< at >gmail.com>wrote:

Re: Error while testing VIFF

shahriar rahman — 2011-08-18T14:26:26

I have got cygwin preinstalled in my pc. The python script is getting
different path than the sys.path. I guess it is because of the cygwin, but
not sure.
I will let you know what happens after removing cygwin.
Thanks.

Re: Error while testing VIFF

Marcel Keller — 2011-08-18T14:04:37

Well, the paths are completely different to the previous output. VIFF 
has to be installed in one of the paths to work. Did you call Python in 
the same way both times? It seems that you use cygwin here, but not earlier.

Regards,
Marcel


shahriar rahman wrote:

Re: Error while testing VIFF

shahriar rahman — 2011-08-17T08:27:41

Hello,

Thanks. I have tried that, but no error shown.

I tried to reinstall different versions as follows:

       Python: 2.5.4
       Twisted: Twisted_NoDocs-8.1.0.win32-py2.5
       OpenSSL: openssl-0.9.8g_win32
       PyOpenSSL: pyOpenSSL-0.7.win32-py2.5
       GMPY: gmpy-1.03-gmp-4.2.1.win32-py2.5
       VIFF: viff-0.7.1


Now, I am getting "No module named viff.config" as earlier. But while trying
to run millionaires.py, I am getting "ImportError: No module named
twisted.internet" instead of "viff.reactor" (that I got earlier). I have
checked the sys.path. Also, "import twisted.internet" does not show any
error.

Any suggestions?

Best regards,
Moha


On Tue, Aug 16, 2011 at 8:04 PM, Marcel Keller <mkeller< at >cs.au.dk> wrote:

Re: Error while testing VIFF

shahriar rahman — 2011-08-15T23:48:30

Hi Marcel,

Thanks. I have checked the sys.path and got the following:

['C:\\Python25\\Lib\\idlelib', 'C:\\Windows\\system32\\python25.zip',
'C:\\Python25\\DLLs', 'C:\\Python25\\lib', 'C:\\Python25\\lib\\plat-win',
'C:\\Python25\\lib\\lib-tk', 'C:\\Python25',
'C:\\Python25\\lib\\site-packages']

Now, how can I move forward?

Thanks again.

Re: Error while testing VIFF

Marcel Keller — 2011-08-16T11:04:08

Hi,

you can try the following:

 >>> import viff.config

If there is an error message, VIFF is not installed properly. If there 
isn't any, my only explanation is that Python uses different paths 
depending on whether executing a script or the command line. The latter 
would seem odd to me.

Best regards,
Marcel


shahriar rahman wrote:

Re: Error while testing VIFF

Marcel Keller — 2011-08-15T10:17:16

Hi,

it seems that Python doesn't find VIFF at all. Can you check whether 
C:\Python25\Lib\site-packages is in sys.path? You can do so as follows:

$ python
 >>> import sys
 >>> sys.path

Best regards,
Marcel


Moha wrote:

Error while testing VIFF

Moha — 2011-08-15T07:53:28

Hello,

I am trying to test and use VIFF for the first time. I am new to python as 
well. I have followed the instructions given in the installation guide at 
viff.dk. The VIFF has been installed with the following versions:

OS: Windows Vista
Python: 2.5.4 
Twisted: Twisted-11.0.0.winxp32-py2.5 
OpenSSL: openssl-0.9.8g_win32 
PyOpenSSL: pyOpenSSL-0.11.winxp32-py2.5 
GMPY: gmpy-1.14.win32-py2.5
VIFF: 1.0

The path is set as: C:\Python25. VIFF is also installed in C:\Python25
\Lib\site-packages\

I have tried to sue both the test options given in the installation guide. But 
have the following error messages:

++method 1:

 python generate-config-files.py -n 3 -t 1 \

error:  traceback(most recent call last):
        File "generate-config-files.py", line 57, in <module>
         from viff.config import generate_configs
        ImportError: No module named viff.config 

++method 2:

 python millionaires.py --no-ssl player-1.ini  (opening 3 seperate command 
prompts as instructed )

error:  traceback(most recent call last):
        File "millionairs.py", line 35, in <module>
         import viff.reactor
        ImportError: No module named viff.reactor

I have no clue on how to solve this problem. Anybody there to help me out?

Re: News

Marcel Keller — 2011-07-15T13:23:24

Hi Apostolis,


I'm afraid to tell you there are no news from my side. However, I cannot 
speak for the BeDOZa part because I'm not involved in its development.


I'm not sure what you mean by a P2P application. Some MPC protocols can 
handle disconnected players (considering them as being malicious), 
however, VIFF will simply abort in such a case. In theory, data could be 
mirrored. That would mean that the corruption of a player mirroring the 
data of another one accounts for two corruptions. VIFF does not 
implement this possibility.


All plans of using MPC (that I know of) go in this direction. However, 
keep in mind that MPC is relatively expensive in terms of network 
communication and computation time. The latter is especially true for 
VIFF, which is implemented in an interpreted language.


I don't have plans of adding features to VIFF. However, I'm happy to 
assist with problems and to include patches that I receive. Moreover, 
what do have in mind when you say "more practical"?

Best regards,
Marcel

News

Apostolis Xekoukoulotakis — 2011-07-14T22:40:38

Are there any news on the Project? Be-D-O-SA documentation?

Is it practical to use VIFF for a P2P application where peer loging off is 
unpredictable? Could their data be mirrored to another peer while keeping them 
secure? How does mirroring change the 'n/3' assumption? 

Just a few noob questions.. :°)

I envision designing an economic system which will be based on having all the 
information. If I am correct MPC also protects against anyone playing agaist the 
rules. So MPC also makes such a design enforcable.

Please continue updating this project and making it more practical.

_______________________________________________
viff-devel mailing list (http://viff.dk/)
viff-devel< at >lists.viff.dk
http://lists.viff.dk/listinfo.cgi/viff-devel-viff.dk

Re: centos install

Marcel Keller — 2011-05-06T09:56:06

Hi Abdelrahaman,

Debian, Ubuntu, and Gentoo offer all dependencies as packages, see
http://viff.dk/doc/install.html#using-a-package-manager

I don't use any IDE for development, just Emacs, which offers code 
highlighting.

Best regards,
Marcel


Abdelrahaman Aly wrote:

Re: centos install

Marcel Keller — 2011-05-02T13:25:05

Hi Abdelrahaman,

it seems that CentOS has neither Twisted nor gmpy in its repository, so 
you have to install both manually. You find instructions for this under:
http://viff.dk/doc/install.html#installing-from-source

In addition, you can do the same for pyOpenSSL, or you can install the 
package of the same name provided by CentOS.

Best regards,
Marcel


Abdelrahaman Aly wrote:

Re: Problem using SSL

Marcel Keller — 2011-05-02T10:01:17

Hi Gilles,

have you tried the simpler applications share-open.py and sum.py? For 
the rest, the error looks like a segmentation fault to me, which would 
indicate a bug in Python or OpenSSL but not VIFF because VIFF is purely 
written in Python. Maybe you should try a newer version of Python and 
pyOpenSSL.

Best regards,
Marcel


Gilles Scuttenaire wrote:

centos install

Abdelrahaman Aly — 2011-05-01T14:03:21

Hello,

My name is Abdelrahaman Aly, Im a Engineering PhD student at UCL, I was
trying to install VIFF in CENTOS but I was not able to do it, there is any
way to do it?

Att.
Abdelrahaman Aly

Problem using SSL

Gilles Scuttenaire — 2011-04-18T14:38:02

Hello,

First of all, sorry for my english...

I have problems when I use SSL. I explain:
I have tried to run the file 'equality.py' in viff\apps. To do that, I
generate config-files and certificates. Then I run 'equality.py player-X.ini
-n 24'  in three different shells.

When I do 'equality.py player-1.ini -n 24' in the first shell, everything
seems to be good. But when I write
'equality.py player-2.ini -n 24'
in the second shell, python simply stops and I receive the following
message:
'Python has stopped working. Windows is trying to find a solution to the
problem.'

I really don't understand what happens.  I have exactly the same problem for
all programs using SSL. However, everything works fine with no SSL.

I use Windows 7 with:
python 2.4.4
twisted 8.10
OpenSSL 1.0.0d (32 bit)
pyOpenSSL  0.7
gmpy 1.10

Thank you for your help.

Re: Newbie question

Marcel Keller — 2011-03-17T14:28:29

Hi Francois,


You should call rt.greater_than_equal(...) instead 
greater_than_equal(...). The latter function does not exists, and its 
call raises an exception. It is a well-known problem of VIFF that 
exceptions within a callback don't appear immediately but get caught 
within Twisted instead. You can do the following to see exceptions 
within the protocol function.

pre_runtime.addCallback(protocol)
def p(x):
     print x
pre_runtime.addErrback(p)

The comparison also requires the field to be quite big. Using the above 
code, you will see an error if the field is not big enough.


- Callbacks get a FieldElement object as the first parameter, not a 
Share object. That means, you cannot open d in dready() because open() 
only accepts Share objects. Instead, you probably want to do the following:

d = rt.greater_than_equal(a,b)
dd = rt.open(d)
dprint("### opened d: %s ###", dd)

- Using several callbacks can be subtle. Your code

d.addCallback(dready)
d.addErrback(problem)

calls problem() if there occurs an error in dready(). If you want to 
catch errors in the computation of d, you have to call

d.addCallbacks(dready, problem)

- You should also wait for dd (i.e. the last result being computed). 
Otherwise, the programs might stop before the computation is completed.

- reactor.callLater(10, reactor.stop) is not necessary if you shut down 
the reactor properly, which you do by calling rt.wait_for(...). 
Furthermore, it will interrupt a computation that takes longer than 10 
seconds.


No because one multiplication takes only a few milliseconds if the 
network latency is low enough.

Best regards,
Marcel

Newbie question

Francois Koeune — 2011-03-16T18:15:26

Hello,

A real beginner question, I am afraid : I just started playing with VIFF.

After installing the tools and running some of the apps example, I tried 
writing my own code, starting by modifying some of the examples.

Taking shamir-share-open.py as a starting point, I started by doing some 
extra computations with the 3 shared values, e.g. computing a*c+b. 
Everything went fine.

Then I wanted to compare some values. So I began by mixing Toft07Runtime 
with the default class, and adding a line like
d = greater_than_equal(a,b)   # (BTW, I know I could do the same with 
the operator >=)

Now the code stalls. Checking the file sort.py, the comparison result 
appears to be a deferred, so I tried adding a callback to d, but with no 
success. I also compared my code with compare.py, but I do not see where 
I deviate from what they do.

Can anybody help me ? Sorry again if the question is stupid, I am a bit 
lost here, and searching mostly by mimicing other programs and trying 
whether it works isn't very efficient.

I am also open to any comment regarding « bad practices » in my 10 lines 
of code, and to any pointer to things I should read to begin with (I 
must confess I am also a beginner to Twisted, but Twisted is a huge 
tool, and it seems difficult to become a Twisted expert before being 
able to play with VIFF).

Last question so far : it seems quite logical to me that the result of 
a comparison is a deferred, and also that the result of an addition is 
immediate. On the other hand, I am a bit surprised that the result of a 
multiplication (cf. my a*b+c above) seems to be immediate, as 
multiplying requires all participants to be involved ... Or perhaps I 
was just extremely lucky to get the result ?

Here is my code :

=====================================================================

import sys

import viff.reactor
viff.reactor.install()
from twisted.internet import reactor

from optparse import OptionParser
from viff.field import GF
from viff.runtime import Runtime, create_runtime, gather_shares
from viff.config import load_config
from viff.util import dprint
from viff.comparison import Toft07Runtime

id, players = load_config(sys.argv[1])
Zp = GF(int(sys.argv[2]))
input = int(sys.argv[3])

print "I am player %d and will input %s" % (id, input)


def protocol(rt):

     def dready(d):
         print "OK"*32
         dd = rt.open(d)
         dprint("### opened d: %s ###", dd)

     def problem(d):
         print "!"*64

     print "-" * 64
     print "Program started"
     print

     a, b, c = rt.shamir_share([1, 2, 3], Zp, input)

     aa = rt.open(a)
     bb = rt.open(b)
     cc = rt.open(c)

     dprint("### opened a: %s ###", aa)
     dprint("### opened b: %s ###", bb)
     dprint("### opened c: %s ###", cc)

     res = a*c+b
     rres = rt.open(res)
     dprint("### opened res: %s ###", rres)

     d = greater_than_equal(a,b)
     d.addCallback(dready)
     d.addErrback(problem)

     rt.wait_for(aa, bb, cc, rres)

pre_runtime = create_runtime(id, players, 1, runtime_class=Toft07Runtime)
pre_runtime.addCallback(protocol)

reactor.callLater(10, reactor.stop)
reactor.run()