Bitwise operations

This document details the bitwise operations supported by TFHE-rs.

Homomorphic integer types support the following bitwise operations:

name	symbol	type
Not	!	Unary
BitAnd	&	Binary
BitOr	|	Binary
BitXor	^	Binary
Shr	>>	Binary
Shl	<<	Binary
Rotate Right	rotate_right	Binary
Rotate Left	rotate_left	Binary

The following example shows how to perform bitwise operations:

use tfhe::prelude::*;
use tfhe::{generate_keys, set_server_key, ConfigBuilder, FheUint8};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let config = ConfigBuilder::default().build();
    let (keys, server_keys) = generate_keys(config);
    set_server_key(server_keys);

    let clear_a = 164;
    let clear_b = 212;

    let mut a = FheUint8::try_encrypt(clear_a, &keys)?;
    let mut b = FheUint8::try_encrypt(clear_b, &keys)?;

    a ^= &b;
    b ^= &a;
    a ^= &b;

    let dec_a: u8 = a.decrypt(&keys);
    let dec_b: u8 = b.decrypt(&keys);

    // We homomorphically swapped values using bitwise operations
    assert_eq!(dec_a, clear_b);
    assert_eq!(dec_b, clear_a);

    Ok(())
}