From 19a824dea8971f15a7b263122b20e46286f89857 Mon Sep 17 00:00:00 2001
From: Aaron Feickert <66188213+AaronFeickert@users.noreply.github.com>
Date: Mon, 26 Feb 2024 02:53:01 -0600
Subject: [PATCH] fix: avoid cloning range proofs during verification (#6166)

Description
---
Removes unnecessary cloning of range proofs during batch verification.

Motivation and Context
---
Currently, range proofs exist in transaction outputs as byte vectors.
When parsing outputs to collect these proofs for batch verification, the
byte vectors are cloned. This is done because the verification API
requires that the vector of proofs contain a vector reference to each
proof, but the `BulletRangeProof` type wrapper provides a slice instead
as part of its `ByteArray` implementation. Because proofs are several
hundred bytes and batches can be large, this cloning is wasteful.

This PR adds `BulletRangeProof::as_vec`, which returns the underlying
range proof as a vector reference. Doing so lets us avoid the clone
while collecting the range proofs.

How Has This Been Tested?
---
Existing tests pass.

What process can a PR reviewer use to test or verify this change?
---
Confirm that the change removes the cloning.
---
 base_layer/common_types/src/types/bullet_rangeproofs.rs     | 5 +++++
 .../transaction_components/transaction_output.rs            | 6 +++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/base_layer/common_types/src/types/bullet_rangeproofs.rs b/base_layer/common_types/src/types/bullet_rangeproofs.rs
index 178e8dd6f7..52b5b27769 100644
--- a/base_layer/common_types/src/types/bullet_rangeproofs.rs
+++ b/base_layer/common_types/src/types/bullet_rangeproofs.rs
@@ -48,6 +48,11 @@ impl BulletRangeProof {
             .expect("This should be 32 bytes for a Blake 256 hash")
             .into()
     }
+
+    /// Get the range proof as a vector reference, which is useful to satisfy the verification API without cloning
+    pub fn as_vec(&self) -> &Vec<u8> {
+        &self.0
+    }
 }
 
 impl ByteArray for BulletRangeProof {
diff --git a/base_layer/core/src/transactions/transaction_components/transaction_output.rs b/base_layer/core/src/transactions/transaction_components/transaction_output.rs
index 9211af456a..5b8331e187 100644
--- a/base_layer/core/src/transactions/transaction_components/transaction_output.rs
+++ b/base_layer/core/src/transactions/transaction_components/transaction_output.rs
@@ -49,7 +49,7 @@ use tari_crypto::{
     extended_range_proof::{ExtendedRangeProofService, Statement},
     keys::SecretKey,
     ristretto::bulletproofs_plus::RistrettoAggregatedPublicStatement,
-    tari_utilities::{hex::Hex, ByteArray},
+    tari_utilities::hex::Hex,
 };
 use tari_script::TariScript;
 
@@ -545,9 +545,9 @@ pub fn batch_verify_range_proofs(
                     minimum_value_promise: output.minimum_value_promise.into(),
                 }],
             });
-            proofs.push(output.proof_result()?.to_vec().clone());
+            proofs.push(output.proof_result()?.as_vec());
         }
-        if let Err(err_1) = prover.verify_batch(proofs.iter().collect(), statements.iter().collect()) {
+        if let Err(err_1) = prover.verify_batch(proofs, statements.iter().collect()) {
             for output in &bulletproof_plus_proofs {
                 if let Err(err_2) = output.verify_range_proof(prover) {
                     return Err(RangeProofError::InvalidRangeProof {