darkfi/script/research/tfhe/src/main.rs

/* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2023 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use tfhe::shortint::{gen_keys, Parameters};

fn main() {
    // Generate a set of client/server keys, using the default parameters.
    // The client generates both keys. The server key is meant to be published
    // so that homomorphic circuits can be computed.
    let (client_key, server_key) = gen_keys(Parameters::default());

    let msg1 = 3;
    let msg2 = 2;

    // Encrypt two messages using the (private) client key:
    let ct_1 = client_key.encrypt(msg1);
    let ct_2 = client_key.encrypt(msg2);

    // Homomorphically compute an addition
    let ct_add = server_key.unchecked_add(&ct_1, &ct_2);

    // Define the Hamming weight function
    // f: x -> sum of the bits of x
    let f = |x: u64| x.count_ones() as u64;

    // Generate the accumulator for the function
    let acc = server_key.generate_accumulator(f);

    // Compute the function over the ciphertext using the PBS
    let ct_res = server_key.keyswitch_programmable_bootstrap(&ct_add, &acc);

    // Decrypt the ciphertext using the (private) client key
    let output = client_key.decrypt(&ct_res);
    assert_eq!(output, f(msg1 + msg2));
    println!("{:#b}", msg1 + msg2);
}