Skip to content

Commit

Permalink
fiat_shamir fix
Browse files Browse the repository at this point in the history
  • Loading branch information
@ktokto313
ktokto313 committed May 10, 2024
1 parent c42008d commit daeda03
Show file tree
Hide file tree
Showing 3 changed files with 46 additions and 47 deletions.
74 changes: 37 additions & 37 deletions fri/src/fiat_shamir/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,16 +7,16 @@ use crate::utils::fields::field_to_usize;
/// A challenge will be hash of `(x,i,last_r,g_i)`
#[derive(Default)]
pub struct Transcript<F: PrimeField> {
/// The last generated challenge
/// The last challenge
last_r: F,
/// The seed, which should be generated from the initialization step
x: F,
/// The current order of query points
/// The current round index
i: u64,
/// The last query point
/// The last challenge evaluation
gi: F,
/// The number of remaining queries that have not been hashed
remain_queries: u64,
/// Variable to keep ROM property that same input should result in same output
input_changed: bool,
}

impl<F: PrimeField> Transcript<F> {
Expand All @@ -26,45 +26,41 @@ impl<F: PrimeField> Transcript<F> {
x: F::ZERO,
i: 0,
gi: F::ZERO,
remain_queries: 0,
input_changed: false,
}
}

fn check_append(&self) {
if self.i == 0 {
println!("Transcript has not been appended!")
println!("Transcript is empty! No message was appended")
}
}

/// Prover use it to send a query
/// Change the last message g_i in the transcript
///
/// # Arguments
///
/// * `merkle_root`: the query
pub fn append(&mut self, merkle_root: F) {
/// * `last_message`: last message g_i
pub fn insert_last_message(&mut self, last_message: F) {
self.i += 1;
if self.remain_queries == 0 {
self.gi = merkle_root;
} else {
self.gi = CustomizedHash::hash_two(self.gi, merkle_root);
}
self.remain_queries += 1;
self.gi = last_message;
self.input_changed = true;
}

/// Generate a single challenge
/// Generate a single challenge r_i
///
/// returns: F: single challenge
/// returns: F: single challenge r_i
pub fn generate_a_challenge(&mut self) -> F {
self.check_append();
if self.remain_queries == 0 {
if !self.input_changed {
return self.last_r;
}
let challenge = CustomizedHash::hash_two(
CustomizedHash::hash_two(self.x, F::from(self.i as u128)),
CustomizedHash::hash_two(self.last_r, self.gi),
);
self.last_r = challenge;
self.remain_queries = 0;
self.input_changed = false;
challenge
}

Expand All @@ -75,25 +71,29 @@ impl<F: PrimeField> Transcript<F> {
/// * `number`: the number of elements
///
/// returns: Vec<F, Global>: list of challenges
//TODO: This is theoretically wrong, g_i should change in every step
pub fn generate_challenge_list(&mut self, number: usize) -> Vec<F> {
self.check_append();
let mut challenges = Vec::<F>::new();
let mut c = self.generate_a_challenge();
for i in 0..number {
challenges.push(c);
c = CustomizedHash::hash_two(c, F::from(i as u128))
c = CustomizedHash::hash_two(
CustomizedHash::hash_two(self.x, F::from(i as u128)),
CustomizedHash::hash_two(c, self.gi),
);
}

challenges
}

/// Similar to generate_a_challenge
pub fn generate_an_index(&mut self) -> usize {
pub fn generate_a_challenge_usize(&mut self) -> usize {
field_to_usize(&self.generate_a_challenge())
}

/// Similar to generate_challenge_list
pub fn generate_index_list(&mut self, number: usize) -> Vec<usize> {
pub fn generate_challenge_list_usize(&mut self, number: usize) -> Vec<usize> {
return self
.generate_challenge_list(number)
.iter()
Expand All @@ -115,12 +115,12 @@ mod tests {
fn test_generate_a_challenge1() {
let mut transcript = Transcript::<Fq>::new();
let query = Fq::from(StdRng::from_entropy().gen::<u128>());
transcript.append(query);
transcript.insert_last_message(query);
let c1 = transcript.generate_a_challenge();
// transcript.append(query);
transcript.insert_last_message(query);
let c2 = transcript.generate_a_challenge();
println!("{:?} {:?}", c1.0, c2.0);
assert_eq!(c1, c2);
assert_ne!(c1, c2);
}

#[test]
Expand All @@ -129,8 +129,8 @@ mod tests {
let query = Fq::from(928459);

let mut transcript2 = Transcript::<Fq>::new();
transcript.append(query);
transcript2.append(query);
transcript.insert_last_message(query);
transcript2.insert_last_message(query);
let c1 = transcript.generate_a_challenge();
// transcript.append(query);
let c2 = transcript2.generate_a_challenge();
Expand All @@ -143,8 +143,8 @@ mod tests {
let mut transcript = Transcript::<Fq>::new();
let mut transcript2 = Transcript::<Fq>::new();
let size = 5;
transcript.append(Fq::from(31313213));
transcript2.append(Fq::from(31313213));
transcript.insert_last_message(Fq::from(31313213));
transcript2.insert_last_message(Fq::from(31313213));
let g = transcript.generate_challenge_list(size);
let g2 = transcript2.generate_challenge_list(size);
println!("g {:?}", g);
Expand All @@ -162,7 +162,7 @@ mod tests {
fn test_generate_challenge_list1() {
let mut transcript = Transcript::<Fq>::new();
let size = 5;
transcript.append(Fq::from(StdRng::from_entropy().gen::<u128>()));
transcript.insert_last_message(Fq::from(StdRng::from_entropy().gen::<u128>()));
let g = transcript.generate_challenge_list(size);
let g2 = transcript.generate_challenge_list(size);
println!("g {:?}", g);
Expand All @@ -179,9 +179,9 @@ mod tests {
#[test]
fn test_generate_an_index() {
let mut t = Transcript::<Fq>::new();
t.append(Fq::from(182887487));
let g1 = t.generate_an_index();
let g2 = t.generate_an_index();
t.insert_last_message(Fq::from(182887487));
let g1 = t.generate_a_challenge();
let g2 = t.generate_a_challenge();
println!("{} {}", g1, g2);
assert_eq!(g1, g2);
}
Expand All @@ -190,9 +190,9 @@ mod tests {
fn test_generate_index_list() {
let mut transcript = Transcript::<Fq>::new();
let size = 5;
transcript.append(Fq::from(StdRng::from_entropy().gen::<u128>()));
let g = transcript.generate_index_list(size);
let g2 = transcript.generate_index_list(size);
transcript.insert_last_message(Fq::from(StdRng::from_entropy().gen::<u128>()));
let g = transcript.generate_challenge_list_usize(size);
let g2 = transcript.generate_challenge_list_usize(size);
println!("{:?} {:?}", g, g2);
assert_eq!(g, g2);
assert_eq!(g.len(), size);
Expand Down
13 changes: 6 additions & 7 deletions fri/src/prover.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@ pub fn commit_phase<F: PrimeField>(
let mut current_layer = FriLayer::new(&cur_poly, &cur_coset, cur_domain_size);

fri_layers.push(current_layer.clone());
transcript.append(current_layer.merkle_tree.root);
transcript.insert_last_message(current_layer.merkle_tree.root);

for _ in 1..number_layers {
let random_r = transcript.generate_a_challenge();
Expand All @@ -68,15 +68,15 @@ pub fn commit_phase<F: PrimeField>(
cur_poly = fold_polynomial(&cur_poly, &random_r);
current_layer = FriLayer::new(&cur_poly, &cur_coset, cur_domain_size);
fri_layers.push(current_layer.clone());
transcript.append(current_layer.merkle_tree.root);
transcript.insert_last_message(current_layer.merkle_tree.root);
}

// the constant commitment
let random_r = transcript.generate_a_challenge();
let last_poly = fold_polynomial(&cur_poly, &random_r);
let const_value = last_poly.coeffs.first().cloned().unwrap_or(F::ZERO);

transcript.append(const_value);
transcript.insert_last_message(const_value);
(const_value, transcript, fri_layers)
}

Expand All @@ -88,7 +88,7 @@ pub fn query_phase<F: PrimeField>(
) -> (Vec<Decommitment<F>>, Vec<usize>) {
if !fri_layers.is_empty() {
let challenge_list = transcript
.generate_index_list(number_of_queries)
.generate_challenge_list_usize(number_of_queries)
.iter()
.map(|v| *v % domain_size)
.collect::<Vec<usize>>();
Expand Down Expand Up @@ -200,8 +200,7 @@ mod tests {
let poly = DensePolynomial::from_coefficients_vec(coeff);
let number_of_layers: usize = 2;
let coset = Fq::GENERATOR;
let (_const_val, _transcript, fri_layers) =
commit_phase(&poly, coset, 4, number_of_layers);
let (_const_val, _transcript, fri_layers) = commit_phase(&poly, coset, 4, number_of_layers);

assert_eq!(fri_layers[1].coset, Fq::from(49));
assert_eq!(fri_layers[1].domain_size, 2);
Expand All @@ -217,7 +216,7 @@ mod tests {
commit_phase(&poly, coset, 4, number_of_layers);
let (decommitment_list, challenge_list) = query_phase(1, 4, &mut transcript, &fri_layers);
let validate_challenge_list = transcript
.generate_index_list(1)
.generate_challenge_list_usize(1)
.iter()
.map(|v| *v % 4)
.collect::<Vec<usize>>();
Expand Down
6 changes: 3 additions & 3 deletions fri/src/verifier.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,15 +12,15 @@ pub fn verify<F: PrimeField>(proof: Proof<F>) -> Result<(), String> {
let random_r_list = merkle_roots
.into_iter()
.map(|root| {
transcript.append(root);
transcript.insert_last_message(root);
transcript.generate_a_challenge()
})
.collect::<Vec<F>>();
transcript.append(proof.const_val);
transcript.insert_last_message(proof.const_val);

// regenerate challenge list
let new_challenge_list = transcript
.generate_index_list(proof.number_of_queries)
.generate_challenge_list_usize(proof.number_of_queries)
.iter()
.map(|v| *v % proof.domain_size)
.collect::<Vec<usize>>();
Expand Down

0 comments on commit daeda03

Please sign in to comment.