Crate tfhe_ntt

tfhe-ntt is a pure Rust high performance number theoretic transform library that processes vectors of sizes that are powers of two.

This library provides three kinds of NTT:

• The prime NTT computes the transform in a field $\mathbb{Z}/p\mathbb{Z}$ with $p$ prime, allowing for arithmetic operations on the polynomial modulo $p$.
• The native NTT internally computes the transform of the first kind with several primes, allowing the simulation of arithmetic modulo the product of those primes, and truncates the result when the inverse transform is desired. The truncated result is guaranteed to be as if the computations were performed with wrapping arithmetic, as long as the full integer result would have been smaller than half the product of the primes, in absolute value. It is guaranteed to be suitable for multiplying two polynomials with arbitrary coefficients, and returns the result in wrapping arithmetic.
• The native binary NTT is similar to the native NTT, but is optimized for the case where one of the operands of the multiplication has coefficients in $\lbrace 0, 1 \rbrace$.

Features

• std (default): This enables runtime arch detection for accelerated SIMD instructions.
• nightly: This enables unstable Rust features to further speed up the NTT, by enabling AVX512 instructions on CPUs that support them. This feature requires a nightly Rust toolchain.

Example

use tfhe_ntt::prime32::Plan;

const N: usize = 32;
let p = 1062862849;
let plan = Plan::try_new(N, p).unwrap();

let data = [
    0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
    25, 26, 27, 28, 29, 30, 31,
];

let mut transformed_fwd = data;
plan.fwd(&mut transformed_fwd);

let mut transformed_inv = transformed_fwd;
plan.inv(&mut transformed_inv);

for (&actual, expected) in transformed_inv
    .iter()
    .zip(data.iter().map(|x| x * N as u32))
{
    assert_eq!(expected, actual);
}

Modules

fastdiv

Fast division by a constant divisor.

native32

Negacyclic NTT for multiplying two polynomials with values less than 2^32.

native64

Negacyclic NTT for multiplying two polynomials with values less than 2^64.

native128

Negacyclic NTT for multiplying two polynomials with values less than 2^128.

native_binary32

Negacyclic NTT for multiplying a polynomial with values less than 2^32 with a binary polynomial.

native_binary64

Negacyclic NTT for multiplying a polynomial with values less than 2^64 with a binary polynomial.

native_binary128

Negacyclic NTT for multiplying a polynomial with values less than 2^128 with a binary polynomial.

prime32

32bit negacyclic NTT for a prime modulus.

prime64

64bit negacyclic NTT for a prime modulus.

product