[viff-devel] [issue89] division error with large divisor

[Nikolaj Volgushev]

New submission from Nikolaj Volgushev <***@bu.edu>:

There is an issue with division by large numbers. I'm submitting a
failing test case in divide.py (attached). To run do the following:

For each of the three players run:
python divide.py --deferred-debug --no-ssl player-{id}.ini
(Note that there is no need to provide input--it's already hard coded).

Check the output of player 2:

Seeding random generator with random seed 6692
Not using SSL
Listening on port 8002
Will connect to <Player 3: localhost:8003>
Connected.
y = 1000000000
l = 10
2**l * y = 1024000000000
modulus = 36893488147419103363
Synchronizing shutdown... The two numbers divided are: {INCORRECT}
done.
Closing connections... done.
Stopping reactor... done.

The result of the division should be 1 however the protocol produces a
large, random-looking number instead. The protocol works fine for
smaller numbers.

Note that the precondition to the division (namely that **l * y <
x.field.modulus) is fulfilled in the above.

----------
messages: 324
nosy: nikolaj
status: unread
title: division error with large divisor
type: bug

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