vexahub/voprf-vx
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General improvements (#65)

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* Relax `hash_to_scalar` and `hash_to_group` bounds

* Rename `util` to `common` and shuffle some stuff around

* Don't generate unnecessary public key

* Simplify 'elliptic-curve` serializing element implementation

* Fix new Clippy 1.59 warnings

* Simplify `Ristretto255::random_scalar` implementation

* Update `derive-where`

* Fix panic during Ristretto255 deserialization

* Remove iteration during de/serialization
This commit is contained in:
daxpedda
2022-04-01 12:18:32 -07:00
committed by GitHub
parent a366a14125
commit 1a61401272
11 changed files with 231 additions and 244 deletions
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src/group/ristretto.rs
+15 -21
View File
@@ -10,7 +10,7 @@ use curve25519_dalek::ristretto::{CompressedRistretto, RistrettoPoint};
use curve25519_dalek::scalar::Scalar;
use curve25519_dalek::traits::Identity;
use digest::core_api::BlockSizeUser;
use digest::OutputSizeUser;
use digest::Digest;
use elliptic_curve::hash2curve::{ExpandMsg, ExpandMsgXmd, Expander};
use generic_array::typenum::{IsLess, IsLessOrEqual, U256, U32, U64};
use generic_array::GenericArray;
@@ -18,7 +18,7 @@ use rand_core::{CryptoRng, RngCore};
use subtle::ConstantTimeEq;
use super::Group;
use crate::{CipherSuite, Error, InternalError, Result};
use crate::{Error, InternalError, Result};
/// [`Group`] implementation for Ristretto255.
#[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
@@ -48,16 +48,13 @@ impl Group for Ristretto255 {
// Implements the `hash_to_ristretto255()` function from
// https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
fn hash_to_curve<CS: CipherSuite>(
input: &[&[u8]],
dst: &[u8],
) -> Result<Self::Elem, InternalError>
fn hash_to_curve<H>(input: &[&[u8]], dst: &[u8]) -> Result<Self::Elem, InternalError>
where
<CS::Hash as OutputSizeUser>::OutputSize:
IsLess<U256> + IsLessOrEqual<<CS::Hash as BlockSizeUser>::BlockSize>,
H: Digest + BlockSizeUser,
H::OutputSize: IsLess<U256> + IsLessOrEqual<H::BlockSize>,
{
let mut uniform_bytes = GenericArray::<_, U64>::default();
ExpandMsgXmd::<CS::Hash>::expand_message(input, dst, 64)
ExpandMsgXmd::<H>::expand_message(input, dst, 64)
.map_err(|_| InternalError::Input)?
.fill_bytes(&mut uniform_bytes);
@@ -66,16 +63,13 @@ impl Group for Ristretto255 {
// Implements the `HashToScalar()` function from
// https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-07.html#section-4.1
fn hash_to_scalar<CS: CipherSuite>(
input: &[&[u8]],
dst: &[u8],
) -> Result<Self::Scalar, InternalError>
fn hash_to_scalar<H>(input: &[&[u8]], dst: &[u8]) -> Result<Self::Scalar, InternalError>
where
<CS::Hash as OutputSizeUser>::OutputSize:
IsLess<U256> + IsLessOrEqual<<CS::Hash as BlockSizeUser>::BlockSize>,
H: Digest + BlockSizeUser,
H::OutputSize: IsLess<U256> + IsLessOrEqual<H::BlockSize>,
{
let mut uniform_bytes = GenericArray::<_, U64>::default();
ExpandMsgXmd::<CS::Hash>::expand_message(input, dst, 64)
ExpandMsgXmd::<H>::expand_message(input, dst, 64)
.map_err(|_| InternalError::Input)?
.fill_bytes(&mut uniform_bytes);
@@ -96,6 +90,10 @@ impl Group for Ristretto255 {
}
fn deserialize_elem(element_bits: &[u8]) -> Result<Self::Elem> {
if element_bits.len() != 32 {
return Err(Error::Deserialization);
}
CompressedRistretto::from_slice(element_bits)
.decompress()
.filter(|point| point != &RistrettoPoint::identity())
@@ -104,11 +102,7 @@ impl Group for Ristretto255 {
fn random_scalar<R: RngCore + CryptoRng>(rng: &mut R) -> Self::Scalar {
loop {
let scalar = {
let mut scalar_bytes = [0u8; 64];
rng.fill_bytes(&mut scalar_bytes);
Scalar::from_bytes_mod_order_wide(&scalar_bytes)
};
let scalar = Scalar::random(rng);
if scalar != Scalar::zero() {
break scalar;