61 lines
1.5 KiB
Rust
61 lines
1.5 KiB
Rust
// -*- mode: rust; -*-
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//
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// This file is part of reddsa.
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// Copyright (c) 2019-2021 Zcash Foundation
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// See LICENSE for licensing information.
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//
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// Authors:
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// - Deirdre Connolly <deirdre@zfnd.org>
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// - Henry de Valence <hdevalence@hdevalence.ca>
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use core::marker::PhantomData;
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use blake2b_simd::{Params, State};
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use crate::{private::SealedScalar, SigType};
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/// Provides H^star, the hash-to-scalar function used by RedDSA.
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pub struct HStar<T: SigType> {
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state: State,
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_marker: PhantomData<T>,
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}
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impl<T: SigType> Default for HStar<T> {
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fn default() -> Self {
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let state = Params::new()
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.hash_length(64)
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.personal(T::H_STAR_PERSONALIZATION)
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.to_state();
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Self {
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state,
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_marker: PhantomData::default(),
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}
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}
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}
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impl<T: SigType> HStar<T> {
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// Only used by FROST code
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#[allow(unused)]
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pub(crate) fn new(personalization_string: &[u8]) -> Self {
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let state = Params::new()
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.hash_length(64)
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.personal(personalization_string)
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.to_state();
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Self {
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state,
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_marker: PhantomData::default(),
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}
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}
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/// Add `data` to the hash, and return `Self` for chaining.
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pub fn update(&mut self, data: impl AsRef<[u8]>) -> &mut Self {
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self.state.update(data.as_ref());
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self
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}
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/// Consume `self` to compute the hash output.
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pub fn finalize(&self) -> T::Scalar {
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T::Scalar::from_bytes_wide(self.state.finalize().as_array())
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}
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}
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