86 lines
2.9 KiB
Rust
86 lines
2.9 KiB
Rust
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// Copyright (c) Facebook, Inc. and its affiliates.
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//
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// This source code is licensed under both the MIT license found in the
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// LICENSE-MIT file in the root directory of this source tree and the Apache
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// License, Version 2.0 found in the LICENSE-APACHE file in the root directory
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// of this source tree.
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use digest::core_api::BlockSizeUser;
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use digest::Digest;
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use elliptic_curve::group::cofactor::CofactorGroup;
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use elliptic_curve::hash2curve::{ExpandMsgXmd, FromOkm, GroupDigest};
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use elliptic_curve::sec1::{FromEncodedPoint, ModulusSize, ToEncodedPoint};
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use elliptic_curve::{
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AffinePoint, Curve, FieldSize, NonZeroScalar, ProjectiveArithmetic, ProjectivePoint, PublicKey,
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Scalar, SecretKey,
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};
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use generic_array::typenum::{IsLess, IsLessOrEqual, U256};
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use generic_array::GenericArray;
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use rand::{CryptoRng, RngCore};
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use super::KeGroup;
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use crate::errors::InternalError;
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impl<G: Curve + GroupDigest + ProjectiveArithmetic> KeGroup for G
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where
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FieldSize<Self>: ModulusSize,
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AffinePoint<Self>: FromEncodedPoint<Self> + ToEncodedPoint<Self>,
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ProjectivePoint<Self>: CofactorGroup + ToEncodedPoint<Self>,
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Scalar<Self>: FromOkm,
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{
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type Pk = PublicKey<Self>;
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type PkLen = <FieldSize<Self> as ModulusSize>::CompressedPointSize;
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type Sk = SecretKey<Self>;
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type SkLen = FieldSize<Self>;
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fn serialize_pk(pk: &Self::Pk) -> GenericArray<u8, Self::PkLen> {
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GenericArray::clone_from_slice(pk.to_encoded_point(true).as_bytes())
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}
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fn deserialize_pk(bytes: &GenericArray<u8, Self::PkLen>) -> Result<Self::Pk, InternalError> {
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PublicKey::from_sec1_bytes(bytes).map_err(|_| InternalError::PointError)
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}
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fn random_sk<R: RngCore + CryptoRng>(rng: &mut R) -> Self::Sk {
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SecretKey::random(rng)
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}
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// Implements the `HashToScalar()` function
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fn hash_to_scalar<H>(input: &[&[u8]], dst: &[u8]) -> Result<Self::Sk, InternalError>
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where
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H: Digest + BlockSizeUser,
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H::OutputSize: IsLess<U256> + IsLessOrEqual<H::BlockSize>,
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{
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Self::hash_to_scalar::<ExpandMsgXmd<H>>(input, dst)
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.ok()
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.and_then(|scalar| Option::<NonZeroScalar<Self>>::from(NonZeroScalar::new(scalar)))
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.map(SecretKey::from)
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.ok_or(InternalError::HashToScalar)
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}
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fn public_key(sk: &Self::Sk) -> Self::Pk {
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sk.public_key()
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}
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fn diffie_hellman(pk: &Self::Pk, sk: &Self::Sk) -> GenericArray<u8, Self::PkLen> {
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GenericArray::clone_from_slice(
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(pk.to_projective() * sk.to_nonzero_scalar().as_ref())
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.to_encoded_point(true)
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.as_bytes(),
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)
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}
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fn zeroize_sk_on_drop(_sk: &mut Self::Sk) {}
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fn serialize_sk(sk: &Self::Sk) -> GenericArray<u8, Self::SkLen> {
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sk.to_be_bytes()
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}
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fn deserialize_sk(bytes: &GenericArray<u8, Self::SkLen>) -> Result<Self::Sk, InternalError> {
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SecretKey::from_be_bytes(bytes).map_err(|_| InternalError::PointError)
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}
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}
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