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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Dear Viff Development Team</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Tomas Toft and I are using ViFF to analyze Toft’s
secure Linear Programming protocol. At the first sight everything seemed to
work nicely, but when trying to increase the number of participants and the threshold
we’ve found an annoying fact about ViFF:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The threshold should be given explicitly when creating the
runtime in any ViFF program. ViFF doesn’t check whether this threshold
matches with the parameters given in the configuration files. Wouldn’t it
be nicer if the threshold is read by “create_runtime(id, players,
threshold, options, Toft05Runtime)” automatically?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Now doing this consistently and setting #players =3 and
threshold =1 works and setting #players=5 and threshold=2 also works. However,
there seems to be some bug somewhere when trying #players=5 and threshold=1.
I’ve altered the millionaires.py such that it deals with 5 players
instead of three and it provides correct output if threshold=2 but correct
output for the participants 1, 2 and 3 only (and junk for players 4 and 5) if
threshold=1… In addition, if I create the config-files with 5 players and
threshold=1 and if I put threshold=2 in the millionaires program, it works
again, i.e., provides correct output….<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hopefully, this information helps you finding the bug. If
anything needs some clarification I’m happy to provide you more
details… <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Sincerely,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Sebastiaan de Hoogh<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>(PhD student at Eindhoven University of Technology) <o:p></o:p></span></font></p>
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