mirror of
https://github.com/saymrwulf/risc0-curve25519-dalek-source.git
synced 2026-09-04 20:03:40 +00:00
216 lines
7.2 KiB
Rust
216 lines
7.2 KiB
Rust
// -*- mode: rust; -*-
|
||
//
|
||
// This file is part of curve25519-dalek.
|
||
// Copyright (c) 2016-2017 Isis Lovecruft, Henry de Valence
|
||
// See LICENSE for licensing information.
|
||
//
|
||
// Authors:
|
||
// - Isis Agora Lovecruft <isis@patternsinthevoid.net>
|
||
// - Henry de Valence <hdevalence@hdevalence.ca>
|
||
|
||
//! This module contains various constants, such as the Ristretto and Ed25519 basepoints.
|
||
//!
|
||
//! Most of the constants are given with
|
||
//! `LONG_DESCRIPTIVE_UPPER_CASE_NAMES`, but they can be brought into
|
||
//! scope using a `let` binding:
|
||
//!
|
||
//! ```
|
||
//! use curve25519_dalek::constants;
|
||
//! use curve25519_dalek::traits::IsIdentity;
|
||
//!
|
||
//! let B = &constants::RISTRETTO_BASEPOINT_TABLE;
|
||
//! let l = &constants::BASEPOINT_ORDER;
|
||
//!
|
||
//! let A = l * B;
|
||
//! assert!(A.is_identity());
|
||
//! ```
|
||
|
||
#![allow(non_snake_case)]
|
||
|
||
use edwards::CompressedEdwardsY;
|
||
use ristretto::RistrettoPoint;
|
||
|
||
use montgomery::CompressedMontgomeryU;
|
||
use scalar::Scalar;
|
||
|
||
#[cfg(feature="radix_51")]
|
||
pub use backend::u64::constants::*;
|
||
#[cfg(not(feature="radix_51"))]
|
||
pub use backend::u32::constants::*;
|
||
|
||
/// Basepoint has y = 4/5.
|
||
///
|
||
/// Generated with Sage: these are the bytes of 4/5 in 𝔽_p. The
|
||
/// sign bit is 0 since the basepoint has x chosen to be positive.
|
||
pub const BASE_CMPRSSD: CompressedEdwardsY =
|
||
CompressedEdwardsY([0x58, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
|
||
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
|
||
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66,
|
||
0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66, 0x66]);
|
||
|
||
/// The X25519 basepoint, in compressed Montgomery form.
|
||
pub const BASE_COMPRESSED_MONTGOMERY: CompressedMontgomeryU =
|
||
CompressedMontgomeryU([0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]);
|
||
|
||
|
||
/// The Ed25519 basepoint, as a `RistrettoPoint`. This is called `_POINT` to distinguish it from
|
||
/// `_TABLE`, which provides fast scalar multiplication.
|
||
pub const RISTRETTO_BASEPOINT_POINT: RistrettoPoint = RistrettoPoint(ED25519_BASEPOINT_POINT);
|
||
|
||
/// `BASEPOINT_ORDER` is the order of base point, i.e. `l = 2^252 +
|
||
/// 27742317777372353535851937790883648493`, in little-endian bytes.
|
||
pub const BASEPOINT_ORDER: Scalar = Scalar{
|
||
bytes: [
|
||
0xed, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,
|
||
0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
|
||
],
|
||
};
|
||
|
||
/// `BASEPOINT_ORDER_MINUS_1` is the order of base point minus one, i.e. `l-1`, in little-endian bytes.
|
||
pub const BASEPOINT_ORDER_MINUS_1: Scalar = Scalar{
|
||
bytes: [
|
||
0xec, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,
|
||
0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
|
||
],
|
||
};
|
||
|
||
/// `BASEPOINT_ORDER_MINUS_2` is the order of base point minus two, i.e. `l-2`, in little-endian bytes.
|
||
pub const BASEPOINT_ORDER_MINUS_2: Scalar = Scalar{
|
||
bytes: [
|
||
0xeb, 0xd3, 0xf5, 0x5c, 0x1a, 0x63, 0x12, 0x58,
|
||
0xd6, 0x9c, 0xf7, 0xa2, 0xde, 0xf9, 0xde, 0x14,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10,
|
||
],
|
||
};
|
||
|
||
// Precomputed basepoint table is generated into a file by build.rs
|
||
|
||
#[cfg(feature="precomputed_tables")]
|
||
include!(concat!(env!("OUT_DIR"), "/basepoint_table.rs"));
|
||
|
||
#[cfg(feature="precomputed_tables")]
|
||
use ristretto::RistrettoBasepointTable;
|
||
/// The Ed25519 basepoint, as a RistrettoPoint
|
||
#[cfg(feature="precomputed_tables")]
|
||
pub const RISTRETTO_BASEPOINT_TABLE: RistrettoBasepointTable
|
||
= RistrettoBasepointTable(ED25519_BASEPOINT_TABLE);
|
||
|
||
#[cfg(test)]
|
||
mod test {
|
||
use field::FieldElement;
|
||
use traits::{IsIdentity, ValidityCheck};
|
||
use constants;
|
||
|
||
#[test]
|
||
fn test_eight_torsion() {
|
||
for i in 0..8 {
|
||
let Q = constants::EIGHT_TORSION[i].mult_by_pow_2(3);
|
||
assert!(Q.is_valid());
|
||
assert!(Q.is_identity());
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn test_four_torsion() {
|
||
for i in (0..8).filter(|i| i % 2 == 0) {
|
||
let Q = constants::EIGHT_TORSION[i].mult_by_pow_2(2);
|
||
assert!(Q.is_valid());
|
||
assert!(Q.is_identity());
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn test_two_torsion() {
|
||
for i in (0..8).filter(|i| i % 4 == 0) {
|
||
let Q = constants::EIGHT_TORSION[i].mult_by_pow_2(1);
|
||
assert!(Q.is_valid());
|
||
assert!(Q.is_identity());
|
||
}
|
||
}
|
||
|
||
/// Test that the constant for sqrt(-486664) really is a square
|
||
/// root of -486664.
|
||
#[test]
|
||
#[cfg(feature="radix_51")]
|
||
fn sqrt_minus_aplus2() {
|
||
use backend::u64::field::FieldElement64;
|
||
let minus_aplus2 = -&FieldElement64([486664,0,0,0,0]);
|
||
let sqrt = constants::SQRT_MINUS_APLUS2;
|
||
let sq = &sqrt * &sqrt;
|
||
assert_eq!(sq, minus_aplus2);
|
||
}
|
||
|
||
/// Test that the constant for sqrt(-486664) really is a square
|
||
/// root of -486664.
|
||
#[test]
|
||
#[cfg(not(feature="radix_51"))]
|
||
fn sqrt_minus_aplus2() {
|
||
use backend::u32::field::FieldElement32;
|
||
let minus_aplus2 = -&FieldElement32([486664,0,0,0,0,0,0,0,0,0]);
|
||
let sqrt = constants::SQRT_MINUS_APLUS2;
|
||
let sq = &sqrt * &sqrt;
|
||
assert_eq!(sq, minus_aplus2);
|
||
}
|
||
|
||
#[test]
|
||
/// Test that SQRT_M1 is a square root of -1
|
||
fn test_sqrt_minus_one() {
|
||
let minus_one = FieldElement::minus_one();
|
||
let sqrt_m1_sq = &constants::SQRT_M1 * &constants::SQRT_M1;
|
||
assert_eq!(minus_one, sqrt_m1_sq);
|
||
}
|
||
|
||
#[test]
|
||
fn test_sqrt_constants_sign() {
|
||
let minus_one = FieldElement::minus_one();
|
||
let (was_nonzero_square, invsqrt_m1) = minus_one.invsqrt();
|
||
assert_eq!(was_nonzero_square, 1u8);
|
||
let sign_test_sqrt = &invsqrt_m1 * &constants::SQRT_M1;
|
||
// XXX it seems we have flipped the sign relative to
|
||
// the invsqrt function?
|
||
assert_eq!(sign_test_sqrt, minus_one);
|
||
}
|
||
|
||
/// Test that d = -121665/121666
|
||
#[cfg(not(feature="radix_51"))]
|
||
#[test]
|
||
fn test_d_vs_ratio() {
|
||
use backend::u32::field::FieldElement32;
|
||
let a = -&FieldElement32([121665,0,0,0,0,0,0,0,0,0]);
|
||
let b = FieldElement32([121666,0,0,0,0,0,0,0,0,0]);
|
||
let d = &a * &b.invert();
|
||
let d2 = &d + &d;
|
||
assert_eq!(d, constants::EDWARDS_D);
|
||
assert_eq!(d2, constants::EDWARDS_D2);
|
||
}
|
||
|
||
/// Test that d = -121665/121666
|
||
#[cfg(feature="radix_51")]
|
||
#[test]
|
||
fn test_d_vs_ratio() {
|
||
use backend::u64::field::FieldElement64;
|
||
let a = -&FieldElement64([121665,0,0,0,0]);
|
||
let b = FieldElement64([121666,0,0,0,0]);
|
||
let d = &a * &b.invert();
|
||
let d2 = &d + &d;
|
||
assert_eq!(d, constants::EDWARDS_D);
|
||
assert_eq!(d2, constants::EDWARDS_D2);
|
||
}
|
||
|
||
#[test]
|
||
fn test_sqrt_ad_minus_one() {
|
||
let a = FieldElement::minus_one();
|
||
let ad_minus_one = &(&a * &constants::EDWARDS_D) + &a;
|
||
let should_be_ad_minus_one = constants::SQRT_AD_MINUS_ONE.square();
|
||
assert_eq!(should_be_ad_minus_one, ad_minus_one);
|
||
}
|
||
|
||
}
|