TNO Protocols

Implementation of the secure comparison protocol.

This building block is included in the TNO MPC Python Toolbox.

Note:

A significant performance improvement for some algorithms can be achieved by installing the GMPY2 library. The protocol currently only uses Paillier, instead of Paillier and DGK.

Install

Install the tno.mpc.protocols package using one of the following options.

  • Personal access token

  • Deploy tokens

  • Cloning this repo (developer mode)

Personal access token

  1. Generate a personal access token with read_api scope. Instruction are found here.

  2. Install

    python -m pip install tno.mpc.protocols.secure_comparison --extra-index-url https://__token__:<personal_access_token>@ci.tno.nl/gitlab/api/v4/projects/7468/packages/pypi/simple

Deploy tokens

  1. Generate a deploy token with read_package_registry scope. Instruction are found here.

  2. Install

    python -m pip install tno.mpc.protocols.secure_comparison --extra-index-url https://<GITLAB_DEPLOY_TOKEN>:<GITLAB_DEPLOY_PASSWORD>@ci.tno.nl/gitlab/api/v4/projects/7468/packages/pypi/simple

Dockerfile

FROM python:3.8

ARG GITLAB_DEPLOY_TOKEN
ARG GITLAB_DEPLOY_PASSWORD

RUN python -m pip install tno.mpc.protocols.secure_comparison --extra-index-url https://$GITLAB_DEPLOY_TOKEN:$GITLAB_DEPLOY_PASSWORD@ci.tno.nl/gitlab/api/v4/projects/7468/packages/pypi/simple

Usage

Usage (examples/example.py):

from tno.mpc.protocols.secure_comparison.secure_comparison import *
from tno.mpc.encryption_schemes.paillier import Paillier

if __name__ == "__main__":
    # Setup the paillier scheme
    scheme = Paillier.from_security_parameter(key_length=2048)

    # Encrypt two numbers (x,y) for the protocol and set the maximum bit_length (l)
    x = 23
    y = 42
    x_enc = scheme.encrypt(x)
    y_enc = scheme.encrypt(y)
    l = 10

    # Execute the protocol steps (Note: a real implementation still needs to take care of the
    # communication.
    z_enc, r = step_1(x_enc, y_enc, l)
    z, beta = step_2(z_enc, l)
    alpha = step_3(r, l)
    d_enc = step_4a(z, scheme)
    beta_is_enc = step_4b(beta, l, scheme)
    d_enc = step_4c(d_enc, r)
    alpha_is_xor_beta_is_enc = step_4d(alpha, beta_is_enc)
    w_is_enc, alpha_tilde = step_4e(r, alpha, alpha_is_xor_beta_is_enc, d_enc)
    w_is_enc = step_4f(w_is_enc)
    s, delta_a = step_4g()
    c_is_enc = step_4h(s, alpha, alpha_tilde, d_enc, beta_is_enc, w_is_enc, delta_a)
    c_is_enc = step_4i(c_is_enc)
    c_is_enc = shuffle(c_is_enc)  # do a random shuffle of c_is_enc
    delta_b = step_4j(c_is_enc)
    zeta_1_enc, zeta_2_enc, delta_b_enc = step_5(z, l, delta_b, scheme)
    beta_lt_alpha_enc = step_6(delta_a, delta_b_enc)
    x_leq_y_enc = step_7(zeta_1_enc, zeta_2_enc, r, l, beta_lt_alpha_enc)
    x_leq_y = scheme.decrypt(x_leq_y_enc)
    assert x_leq_y == 1

Indices and tables