diff --git a/examples/src/rescue_raps/air.rs b/examples/src/rescue_raps/air.rs
index 7d3d3b66d..2ede0f1a6 100644
--- a/examples/src/rescue_raps/air.rs
+++ b/examples/src/rescue_raps/air.rs
@@ -104,6 +104,7 @@ impl Air for RescueRapsAir {
let ark = &periodic_values[2..];
// when hash_flag = 1, constraints for Rescue round are enforced (steps 0 to 14)
+ // Enforcing the round for the first hash chain
rescue::enforce_round(
&mut result[..STATE_WIDTH],
¤t[..STATE_WIDTH],
@@ -112,6 +113,7 @@ impl Air for RescueRapsAir {
hash_flag,
);
+ // Enforcing the round for the second hash chain
rescue::enforce_round(
&mut result[STATE_WIDTH..],
¤t[STATE_WIDTH..],
@@ -172,11 +174,18 @@ impl Air for RescueRapsAir {
let absorption_flag = periodic_values[1];
// We want to enforce that the absorbed values of the first hash chain are a
- // permutation of the absorbed values of the second one. Because we want to
- // copy two values per hash chain (namely the two capacity registers), we
- // group them with random elements into a single cell via
+ // permutation of the absorbed values of the second one. Recall that the type
+ // for both seed and permuted_seed (the arrays being hashed into the chain), was
+ // [[BaseElement; 2]] and we never permute any of the internal arrays, since
+ // each [BaseElement; 2] represents the capacity registers for a single link in the
+ // hash chain. Due to this, we want to copy two values per hash chain at iteration
+ // (namely, the two capacity registers). To reduce the number of auxiliary registers needed
+ // to represent each link, we group them with random elements into a single cell via
// α_0 * c_0 + α_1 * c_1, where c_i is computed as next_i - current_i.
+ // Note that the reason we use next_i - current_i is that we are
+ // absorbing the new seed by adding it to the output of the previous hash.
+
// Note that storing the copied values into two auxiliary columns. One could
// instead directly compute the permutation argument, hence require a single
// auxiliary one. For the sake of illustrating RAPs behaviour, we will store
diff --git a/examples/src/rescue_raps/prover.rs b/examples/src/rescue_raps/prover.rs
index 2f05cfac9..3b4e1a77e 100644
--- a/examples/src/rescue_raps/prover.rs
+++ b/examples/src/rescue_raps/prover.rs
@@ -10,7 +10,10 @@ use super::{
// RESCUE PROVER
// ================================================================================================
-
+/// This example constructs a proof for correct execution of
+/// 2 hash chains simultaneously.
+/// In order to demonstrate the power of RAPs, the two hash chains have seeds that are
+/// permutations of each other.
pub struct RescueRapsProver {
options: ProofOptions,
}
@@ -19,7 +22,8 @@ impl RescueRapsProver {
pub fn new(options: ProofOptions) -> Self {
Self { options }
}
-
+ /// The parameter `seeds` is the set of seeds for the first hash chain.
+ /// The parameter `permuted_seeds` is the set of seeds for the second hash chain.
pub fn build_trace(
&self,
seeds: &[[BaseElement; 2]],
diff --git a/fri/src/lib.rs b/fri/src/lib.rs
index 8e1cf8dca..45e027c5f 100644
--- a/fri/src/lib.rs
+++ b/fri/src/lib.rs
@@ -84,4 +84,4 @@ pub use proof::FriProof;
mod errors;
pub use errors::VerifierError;
-mod utils;
+pub mod utils;
diff --git a/math/README.md b/math/README.md
index 2de05d9ec..7bacd1f7b 100644
--- a/math/README.md
+++ b/math/README.md
@@ -8,7 +8,7 @@ This crate contains modules with mathematical operations needed in STARK proof g
* Drawing random and pseudo-random elements from the field.
* Computing roots of unity of a given order.
-Currently, there are two implementations of finite fields:
+Currently, there are three implementations of finite fields:
* A 128-bit field with modulus 2128 - 45 * 240 + 1. This field was not chosen with any significant thought given to performance, and the implementation of most operations is sub-optimal as well. Proofs generated in this field can support security level of ~100 bits. If higher level of security is desired, proofs must be generated in a quadratic extension of the field.
* A 62-bit field with modulus 262 - 111 * 239 + 1. This field supports very fast modular arithmetic including branchless multiplication and addition. To achieve adequate security (i.e. ~100 bits), proofs must be generated in a quadratic extension of this field. For higher levels of security, a cubic extension field should be used.
@@ -69,4 +69,4 @@ The number of threads can be configured via `RAYON_NUM_THREADS` environment vari
License
-------
-This project is [MIT licensed](../LICENSE).
\ No newline at end of file
+This project is [MIT licensed](../LICENSE).