mirror of
https://github.com/serai-dex/serai.git
synced 2025-12-12 14:09:25 +00:00
90 lines
2.6 KiB
Rust
90 lines
2.6 KiB
Rust
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
|
|
#![doc = include_str!("../README.md")]
|
|
#![cfg_attr(not(feature = "std"), no_std)]
|
|
|
|
use std_shims::{sync::OnceLock, vec::Vec};
|
|
|
|
use sha3::{Digest, Keccak256};
|
|
|
|
use curve25519_dalek::edwards::{EdwardsPoint as DalekPoint};
|
|
|
|
use group::{Group, GroupEncoding};
|
|
use dalek_ff_group::EdwardsPoint;
|
|
|
|
use monero_io::{write_varint, decompress_point};
|
|
|
|
mod hash_to_point;
|
|
pub use hash_to_point::hash_to_point;
|
|
|
|
#[cfg(test)]
|
|
mod tests;
|
|
|
|
fn keccak256(data: &[u8]) -> [u8; 32] {
|
|
Keccak256::digest(data).into()
|
|
}
|
|
|
|
static H_CELL: OnceLock<DalekPoint> = OnceLock::new();
|
|
/// Monero's `H` generator.
|
|
///
|
|
/// Contrary to convention (`G` for values, `H` for randomness), `H` is used by Monero for amounts
|
|
/// within Pedersen commitments.
|
|
#[allow(non_snake_case)]
|
|
pub fn H() -> DalekPoint {
|
|
*H_CELL.get_or_init(|| {
|
|
decompress_point(keccak256(&EdwardsPoint::generator().to_bytes())).unwrap().mul_by_cofactor()
|
|
})
|
|
}
|
|
|
|
static H_POW_2_CELL: OnceLock<[DalekPoint; 64]> = OnceLock::new();
|
|
/// Monero's `H` generator, multiplied by 2**i for i in 1 ..= 64.
|
|
///
|
|
/// This table is useful when working with amounts, which are u64s.
|
|
#[allow(non_snake_case)]
|
|
pub fn H_pow_2() -> &'static [DalekPoint; 64] {
|
|
H_POW_2_CELL.get_or_init(|| {
|
|
let mut res = [H(); 64];
|
|
for i in 1 .. 64 {
|
|
res[i] = res[i - 1] + res[i - 1];
|
|
}
|
|
res
|
|
})
|
|
}
|
|
|
|
// The maximum amount of commitments proven for within a single range proof.
|
|
const MAX_M: usize = 16;
|
|
// The amount of bits the value within a commitment may use.
|
|
const N: usize = 64;
|
|
// The maximum amount of bits used within a single range proof.
|
|
const MAX_MN: usize = MAX_M * N;
|
|
|
|
/// Container struct for Bulletproofs(+) generators.
|
|
#[allow(non_snake_case)]
|
|
pub struct Generators {
|
|
pub G: Vec<EdwardsPoint>,
|
|
pub H: Vec<EdwardsPoint>,
|
|
}
|
|
|
|
/// Generate generators as needed for Bulletproofs(+), as Monero does.
|
|
///
|
|
/// Consumers should not call this function ad-hoc, yet call it within a build script or use a
|
|
/// once-initialized static.
|
|
pub fn bulletproofs_generators(dst: &'static [u8]) -> Generators {
|
|
let mut preimage = H().compress().to_bytes().to_vec();
|
|
preimage.extend(dst);
|
|
|
|
let mut res = Generators { G: Vec::with_capacity(MAX_MN), H: Vec::with_capacity(MAX_MN) };
|
|
for i in 0 .. MAX_MN {
|
|
// We generate a pair of generators per iteration
|
|
let i = 2 * i;
|
|
|
|
let mut even = preimage.clone();
|
|
write_varint(&i, &mut even).unwrap();
|
|
res.H.push(EdwardsPoint(hash_to_point(keccak256(&even))));
|
|
|
|
let mut odd = preimage.clone();
|
|
write_varint(&(i + 1), &mut odd).unwrap();
|
|
res.G.push(EdwardsPoint(hash_to_point(keccak256(&odd))));
|
|
}
|
|
res
|
|
}
|