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Merge GroupWithMapToCurve into Group (#219)

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* Merge `GroupWithMapToCurve` into `Group`

* Remove `hash_to_curve`

* Ristretto improvements

* P-256 improvements
This commit is contained in:
daxpedda
2021-08-01 17:48:56 -07:00
committed by GitHub
parent a169d8a1c5
commit 10a38bc58b
10 changed files with 136 additions and 195 deletions
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src/group/ristretto.rs
+38 -31
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@@ -3,34 +3,56 @@
// This source code is licensed under the MIT license found in the
// LICENSE file in the root directory of this source tree.
use crate::errors::InternalPakeError;
use super::Group;
use crate::errors::{InternalPakeError, ProtocolError};
use crate::hash::Hash;
use curve25519_dalek::{
constants::RISTRETTO_BASEPOINT_POINT,
ristretto::{CompressedRistretto, RistrettoPoint},
scalar::Scalar,
traits::Identity,
};
use generic_array::{
typenum::{U32, U64},
GenericArray,
};
use std::convert::TryInto;
use generic_array::{typenum::U32, GenericArray};
use rand::{CryptoRng, RngCore};
use super::Group;
use std::convert::TryInto;
use subtle::ConstantTimeEq;
/// The implementation of such a subgroup for Ristretto
impl Group for RistrettoPoint {
const SUITE_ID: usize = 0x0001;
// Implements the `hash_to_ristretto255()` function from
// https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, ProtocolError> {
let uniform_bytes = super::expand::expand_message_xmd::<H>(msg, dst, 64)?;
Ok(RistrettoPoint::from_uniform_bytes(
uniform_bytes
.as_slice()
.try_into()
.map_err(|_| InternalPakeError::HashToCurveError)?,
))
}
// Implements the `HashToScalar()` function from
// https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-07.html#section-4.1
fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8]) -> Result<Self::Scalar, ProtocolError> {
let uniform_bytes = super::expand::expand_message_xmd::<H>(input, dst, 64)?;
Ok(Scalar::from_bytes_mod_order_wide(
uniform_bytes
.as_slice()
.try_into()
.map_err(|_| InternalPakeError::HashToCurveError)?,
))
}
type Scalar = Scalar;
type ScalarLen = U32;
fn from_scalar_slice(
scalar_bits: &GenericArray<u8, Self::ScalarLen>,
) -> Result<Self::Scalar, InternalPakeError> {
let mut bits = [0u8; 32];
bits.copy_from_slice(scalar_bits);
Ok(Scalar::from_bytes_mod_order(bits))
Ok(Scalar::from_bytes_mod_order(*scalar_bits.as_ref()))
}
fn random_nonzero_scalar<R: RngCore + CryptoRng>(rng: &mut R) -> Self::Scalar {
loop {
@@ -74,21 +96,7 @@ impl Group for RistrettoPoint {
}
// serialization of a group element
fn to_arr(&self) -> GenericArray<u8, Self::ElemLen> {
let c = self.compress();
*GenericArray::from_slice(c.as_bytes())
}
type UniformBytesLen = U64;
fn hash_to_curve(
uniform_bytes: &GenericArray<u8, Self::UniformBytesLen>,
) -> Result<Self, InternalPakeError> {
// https://caniuse.rs/features/array_gt_32_impls
let bits: [u8; 64] = {
let mut bytes = [0u8; 64];
bytes.copy_from_slice(uniform_bytes);
bytes
};
Ok(RistrettoPoint::from_uniform_bytes(&bits))
self.compress().to_bytes().into()
}
fn base_point() -> Self {
@@ -96,8 +104,7 @@ impl Group for RistrettoPoint {
}
fn mult_by_slice(&self, scalar: &GenericArray<u8, Self::ScalarLen>) -> Self {
let arr: [u8; 32] = scalar.as_slice().try_into().expect("Wrong length");
self * Scalar::from_bits(arr)
self * Scalar::from_bits(*scalar.as_ref())
}
/// Returns if the group element is equal to the identity (1)
@@ -106,6 +113,6 @@ impl Group for RistrettoPoint {
}
fn ct_equal(&self, other: &Self) -> bool {
constant_time_eq::constant_time_eq(&self.to_arr(), &other.to_arr())
ConstantTimeEq::ct_eq(self, other).into()
}
}