Equality Comparison

This notebook demonstrates comparing secret shared arrays elementwise for equality. The resulting secret shared array will be the same shape as the inputs, containing \(1\) where the inputs are equal, and \(0\) where they are not. Note that we use the Boolean encoding when we reveal the output because the default FixedPoint encoding would produce unexpected results.

The following example compares \([1, -2, 3, -4.5]\) to \([1, 2, 3, -4.5]\) and returns \([1, 0, 1, 1]\):

[1]:

import logging

import numpy

from cicada.additive import AdditiveProtocolSuite
from cicada.communicator import SocketCommunicator
from cicada.encoding import Boolean
from cicada.logging import Logger

logging.basicConfig(level=logging.INFO)


def main(communicator):
    log = Logger(logging.getLogger(), communicator)
    protocol = AdditiveProtocolSuite(communicator)

    a = numpy.array([1, -2, 3, -4.5]) if communicator.rank == 0 else None
    b = numpy.array([1, 2, 3, -4.5]) if communicator.rank == 1 else None

    log.info(f"Player {communicator.rank} secret: {a}", src=0)
    log.info(f"Player {communicator.rank} secret: {b}", src=1)

    a_share = protocol.share(src=0, secret=a, shape=(4,))
    b_share = protocol.share(src=1, secret=b, shape=(4,))
    equal_share = protocol.equal(a_share, b_share)
    equal = protocol.reveal(equal_share, encoding=Boolean())

    log.info(f"Player {communicator.rank} result: {equal}")

SocketCommunicator.run(world_size=3, fn=main);

INFO:root:Player 0 secret: [ 1.  -2.   3.  -4.5]
INFO:root:Player 1 secret: [ 1.   2.   3.  -4.5]
INFO:root:Player 0 result: [ True False  True  True]
INFO:root:Player 1 result: [ True False  True  True]
INFO:root:Player 2 result: [ True False  True  True]