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* Document all features * Largely document the Monero libraries Relevant to https://github.com/serai-dex/serai/issues/103 and likely sufficient to get this removed from https://github.com/serai-dex/serai/issues/102.
74 lines
2.2 KiB
Rust
74 lines
2.2 KiB
Rust
use std::io::Read;
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use thiserror::Error;
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use rand_core::{RngCore, CryptoRng};
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use zeroize::Zeroize;
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use curve25519_dalek::{scalar::Scalar, edwards::EdwardsPoint};
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use group::{Group, GroupEncoding};
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use transcript::{Transcript, RecommendedTranscript};
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use dalek_ff_group as dfg;
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use dleq::DLEqProof;
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#[derive(Clone, Error, Debug)]
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pub(crate) enum MultisigError {
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#[error("invalid discrete log equality proof")]
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InvalidDLEqProof(u16),
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}
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fn transcript() -> RecommendedTranscript {
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RecommendedTranscript::new(b"monero_key_image_dleq")
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}
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#[allow(non_snake_case)]
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pub(crate) fn write_dleq<R: RngCore + CryptoRng>(
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rng: &mut R,
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H: EdwardsPoint,
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mut x: Scalar,
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) -> Vec<u8> {
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let mut res = Vec::with_capacity(64);
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DLEqProof::prove(
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rng,
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// Doesn't take in a larger transcript object due to the usage of this
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// Every prover would immediately write their own DLEq proof, when they can only do so in
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// the proper order if they want to reach consensus
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// It'd be a poor API to have CLSAG define a new transcript solely to pass here, just to try to
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// merge later in some form, when it should instead just merge xH (as it does)
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&mut transcript(),
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&[dfg::EdwardsPoint::generator(), dfg::EdwardsPoint(H)],
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dfg::Scalar(x),
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)
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.serialize(&mut res)
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.unwrap();
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x.zeroize();
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res
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}
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#[allow(non_snake_case)]
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pub(crate) fn read_dleq<Re: Read>(
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serialized: &mut Re,
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H: EdwardsPoint,
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l: u16,
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xG: dfg::EdwardsPoint,
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) -> Result<dfg::EdwardsPoint, MultisigError> {
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let mut bytes = [0; 32];
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serialized.read_exact(&mut bytes).map_err(|_| MultisigError::InvalidDLEqProof(l))?;
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// dfg ensures the point is torsion free
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let xH = Option::<dfg::EdwardsPoint>::from(dfg::EdwardsPoint::from_bytes(&bytes))
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.ok_or(MultisigError::InvalidDLEqProof(l))?;
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// Ensure this is a canonical point
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if xH.to_bytes() != bytes {
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Err(MultisigError::InvalidDLEqProof(l))?;
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}
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DLEqProof::<dfg::EdwardsPoint>::deserialize(serialized)
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.map_err(|_| MultisigError::InvalidDLEqProof(l))?
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.verify(&mut transcript(), &[dfg::EdwardsPoint::generator(), dfg::EdwardsPoint(H)], &[xG, xH])
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.map_err(|_| MultisigError::InvalidDLEqProof(l))?;
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Ok(xH)
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}
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