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Fix no_std support (#229)

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This commit is contained in:
daxpedda
2021-08-16 20:11:53 -07:00
committed by GitHub
parent 8a7bcf9097
commit 6c7840514d
15 changed files with 179 additions and 208 deletions
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src/group/expand.rs
+2 -2
View File
@@ -31,8 +31,8 @@ pub fn expand_message_xmd<H: Hash>(
dst: &[u8],
len_in_bytes: usize,
) -> Result<Vec<u8>, ProtocolError> {
let b_in_bytes = <H as Digest>::OutputSize::to_usize();
let r_in_bytes = <H as BlockInput>::BlockSize::to_usize();
let b_in_bytes = <H as Digest>::OutputSize::USIZE;
let r_in_bytes = <H as BlockInput>::BlockSize::USIZE;
let ell = div_ceil(len_in_bytes, b_in_bytes);
if ell > 255 {
src/group/p256.rs
+50 -35
View File
@@ -18,7 +18,7 @@ use generic_array::{ArrayLength, GenericArray};
use num_bigint::{BigInt, Sign};
use num_integer::Integer;
use num_traits::{One, ToPrimitive};
use once_cell::sync::Lazy;
use once_cell::unsync::Lazy;
use p256_::elliptic_curve::group::prime::PrimeCurveAffine;
use p256_::elliptic_curve::group::GroupEncoding;
use p256_::elliptic_curve::sec1::{FromEncodedPoint, ToEncodedPoint};
@@ -27,50 +27,41 @@ use p256_::elliptic_curve::Field;
use p256_::{AffinePoint, EncodedPoint, ProjectivePoint};
use rand::{CryptoRng, RngCore};
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-8.2
// `p: 2^256 - 2^224 + 2^192 + 2^96 - 1`
const P: Lazy<BigInt> = Lazy::new(|| {
BigInt::from_str(
"115792089210356248762697446949407573530086143415290314195533631308867097853951",
)
.unwrap()
});
// `A: -3`
const A: Lazy<BigInt> = Lazy::new(|| BigInt::from(-3));
// `B: 0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b`
const B: Lazy<BigInt> = Lazy::new(|| {
BigInt::parse_bytes(
b"5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b",
16,
)
.unwrap()
});
// `L: 48`
pub const L: usize = 48;
// `Z: -10`
const Z: Lazy<BigInt> = Lazy::new(|| BigInt::from(-10));
// https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf#[{%22num%22:211,%22gen%22:0},{%22name%22:%22XYZ%22},70,700,0]
// P-256 `n` is defined as `115792089210356248762697446949407573529996955224135760342 422259061068512044369`
pub const N: Lazy<BigInt> = Lazy::new(|| {
BigInt::from_str(
"115792089210356248762697446949407573529996955224135760342422259061068512044369",
)
.unwrap()
});
#[cfg(feature = "p256")]
impl Group for ProjectivePoint {
const SUITE_ID: usize = 0x0003;
// Implements the `hash_to_curve()` function from
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-3
fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, ProtocolError> {
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-8.2
// `p: 2^256 - 2^224 + 2^192 + 2^96 - 1`
const P: Lazy<BigInt> = Lazy::new(|| {
BigInt::from_str(
"115792089210356248762697446949407573530086143415290314195533631308867097853951",
)
.unwrap()
});
// `A: -3`
const A: Lazy<BigInt> = Lazy::new(|| BigInt::from(-3));
// `B: 0x5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b`
const B: Lazy<BigInt> = Lazy::new(|| {
BigInt::parse_bytes(
b"5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b",
16,
)
.unwrap()
});
// `Z: -10`
const Z: Lazy<BigInt> = Lazy::new(|| BigInt::from(-10));
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-3
// `hash_to_curve` calls `hash_to_field` with a `count` of `2`
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-5.3
// `hash_to_field` calls `expand_message` with a `len_in_bytes` of `count * L`
let uniform_bytes =
super::expand::expand_message_xmd::<H>(msg, dst, 2 * crate::group::p256::L)?;
let uniform_bytes = super::expand::expand_message_xmd::<H>(msg, dst, 2 * L)?;
// map to curve
let (q0x, q0y) = map_to_curve_simple_swu(&uniform_bytes[..L], &A, &B, &P, &Z);
@@ -93,12 +84,20 @@ impl Group for ProjectivePoint {
// Implements the `HashToScalar()` function from
// https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-07.html#section-4.3
fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8]) -> Result<Self::Scalar, ProtocolError> {
// https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-4.pdf#[{%22num%22:211,%22gen%22:0},{%22name%22:%22XYZ%22},70,700,0]
// P-256 `n` is defined as `115792089210356248762697446949407573529996955224135760342 422259061068512044369`
const N: once_cell::unsync::Lazy<BigInt> = once_cell::unsync::Lazy::new(|| {
BigInt::from_str(
"115792089210356248762697446949407573529996955224135760342422259061068512044369",
)
.unwrap()
});
// https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#section-5.3
// `HashToScalar` is `hash_to_field`
let uniform_bytes =
super::expand::expand_message_xmd::<H>(input, dst, crate::group::p256::L)?;
let uniform_bytes = super::expand::expand_message_xmd::<H>(input, dst, L)?;
let mut bytes = BigInt::from_bytes_be(Sign::Plus, &uniform_bytes)
.mod_floor(&crate::group::p256::N)
.mod_floor(&N)
.to_bytes_be()
.1;
bytes.resize(32, 0);
@@ -410,6 +409,22 @@ mod tests {
#[test]
fn map_to_curve_simple_swu() {
const P: Lazy<BigInt> = Lazy::new(|| {
BigInt::from_str(
"115792089210356248762697446949407573530086143415290314195533631308867097853951",
)
.unwrap()
});
const A: Lazy<BigInt> = Lazy::new(|| BigInt::from(-3));
const B: Lazy<BigInt> = Lazy::new(|| {
BigInt::parse_bytes(
b"5ac635d8aa3a93e7b3ebbd55769886bc651d06b0cc53b0f63bce3c3e27d2604b",
16,
)
.unwrap()
});
const Z: Lazy<BigInt> = Lazy::new(|| BigInt::from(-10));
// Test vectors taken from https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-hash-to-curve-11#appendix-J.1.1
let test_vectors = alloc::vec![
Params {