mirror of
https://github.com/mii443/RustySecrets.git
synced 2025-08-22 16:25:32 +00:00
73e45bf032
Horner's method is an algorithm for calculating polynomials, which consists of transforming the monomial form into a computationally efficient form. It is pretty easy to understand: https://en.wikipedia.org/wiki/Horner%27s_method#Description_of_the_algorithm This implementation has resulted in a noticeable secret share generation speedup as the RustySecrets benchmarks show, especially when calculating larger polynomials: Before: test sss::generate_1kb_10_25 ... bench: 3,104,391 ns/iter (+/- 113,824) test sss::generate_1kb_3_5 ... bench: 951,807 ns/iter (+/- 41,067) After: test sss::generate_1kb_10_25 ... bench: 2,071,655 ns/iter (+/- 46,445) test sss::generate_1kb_3_5 ... bench: 869,875 ns/iter (+/- 40,246)
16 lines
485 B
Rust
16 lines
485 B
Rust
use gf256::Gf256;
|
|
use std::io;
|
|
use std::io::prelude::*;
|
|
|
|
/// evaluates a polynomial at x=1, 2, 3, ... n (inclusive)
|
|
pub(crate) fn encode_secret_byte<W: Write>(src: &[u8], n: u8, w: &mut W) -> io::Result<()> {
|
|
for raw_x in 1..(u16::from(n) + 1) {
|
|
let x = Gf256::from_byte(raw_x as u8);
|
|
let sum = src.iter().rev().fold(Gf256::zero(), |acc, &coeff| {
|
|
Gf256::from_byte(coeff) + acc * x
|
|
});
|
|
w.write_all(&[sum.to_byte()])?;
|
|
}
|
|
Ok(())
|
|
}
|