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Transcript crate with both a merlin backend and a basic label len value backend

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Moves binding factor/seeded RNGs over to the transcripts.
This commit is contained in:
Luke Parker
2022-05-03 07:20:24 -04:00
parent 87f38cafe4
commit bf257b3a1f
19 changed files with 282 additions and 129 deletions
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21
coins/monero/src/transaction/mod.rs
View File

@@ -1,8 +1,6 @@
use rand_core::{RngCore, CryptoRng, SeedableRng};
use rand_chacha::ChaCha12Rng;
use thiserror::Error;
use blake2::{Digest, Blake2b512};
use rand_core::{RngCore, CryptoRng};
use curve25519_dalek::{
constants::ED25519_BASEPOINT_TABLE,
@@ -26,10 +24,13 @@ use monero::{
}
};
use transcript::Transcript as TranscriptTrait;
#[cfg(feature = "multisig")]
use frost::FrostError;
use crate::{
Transcript,
Commitment,
random_scalar,
hash, hash_to_scalar,
@@ -264,6 +265,9 @@ impl SignableTransaction {
)
}
// This could be refactored so prep, a multisig-required variable, is used only by multisig
// Not shimmed by the single signer API as well
// This would enable moving Transcript as a whole to the multisig feature
fn prepare_outputs<'a, R: RngCore + CryptoRng>(
&self,
prep: &mut Preparation<'a, R>
@@ -289,6 +293,7 @@ impl SignableTransaction {
match prep {
Preparation::Leader(ref mut rng) => {
// The Leader generates the entropy for the one time keys and the bulletproof
// This prevents de-anonymization via recalculation of the randomness which is deterministic
rng.fill_bytes(&mut entropy);
},
Preparation::Follower(e, b) => {
@@ -297,16 +302,14 @@ impl SignableTransaction {
}
}
let mut seed = b"StealthAddress_randomness".to_vec();
// Leader selected entropy to prevent de-anonymization via recalculation of randomness
seed.extend(&entropy);
let mut transcript = Transcript::new(b"StealthAddress");
// This output can only be spent once. Therefore, it forces all one time keys used here to be
// unique, even if the leader reuses entropy. While another transaction could use a different
// input ordering to swap which 0 is, that input set can't contain this input without being a
// double spend
seed.extend(&self.inputs[0].tx.0);
seed.extend(&self.inputs[0].o.to_le_bytes());
let mut rng = ChaCha12Rng::from_seed(Blake2b512::digest(seed)[0 .. 32].try_into().unwrap());
transcript.append_message(b"hash", &self.inputs[0].tx.0);
transcript.append_message(b"index", &u64::try_from(self.inputs[0].o).unwrap().to_le_bytes());
let mut rng = transcript.seeded_rng(b"tx_keys", Some(entropy));
let mut outputs = Vec::with_capacity(payments.len());
let mut commitments = Vec::with_capacity(payments.len());

9
coins/monero/src/transaction/multisig.rs
View File

@@ -1,12 +1,9 @@
use std::{rc::Rc, cell::RefCell};
use rand_core::{RngCore, CryptoRng};
use rand_chacha::ChaCha12Rng;
use curve25519_dalek::{scalar::Scalar, edwards::{EdwardsPoint, CompressedEdwardsY}};
use frost::{FrostError, MultisigKeys, MultisigParams, sign::{State, StateMachine, AlgorithmMachine}};
use monero::{
Hash, VarInt,
consensus::deserialize,
@@ -14,7 +11,11 @@ use monero::{
blockdata::transaction::{KeyImage, TxIn, Transaction}
};
use transcript::Transcript as TranscriptTrait;
use frost::{FrostError, MultisigKeys, MultisigParams, sign::{State, StateMachine, AlgorithmMachine}};
use crate::{
Transcript,
frost::Ed25519,
key_image,
clsag,
@@ -150,7 +151,7 @@ impl StateMachine for TransactionMachine {
let prep = prep.as_ref().unwrap();
// Handle the prep with a seeded RNG type to make rustc happy
let (_, mask_sum, tx_inner) = self.signable.prepare_outputs::<ChaCha12Rng>(
let (_, mask_sum, tx_inner) = self.signable.prepare_outputs::<<Transcript as TranscriptTrait>::SeededRng>(
&mut Preparation::Follower(
prep[clsag_lens .. (clsag_lens + 32)].try_into().map_err(|_| FrostError::InvalidCommitment(l))?,
deserialize(&prep[(clsag_lens + 32) .. prep.len()]).map_err(|_| FrostError::InvalidCommitment(l))?