From ea4980c6e2cc438c5763e1eabd774f1d6b520602 Mon Sep 17 00:00:00 2001
From: aniampio <anna.piotrowska.15@ucl.ac.uk>
Date: Tue, 24 Oct 2023 15:02:19 +0100
Subject: [PATCH] Improve function performance and readability

---
 .../src/proofs/proof_spend.rs                 |  2 +-
 .../src/scheme/identify.rs                    | 14 +++++------
 .../src/scheme/mod.rs                         | 23 +++++++++----------
 .../src/tests/e2e.rs                          |  2 +-
 4 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/common/nym_offline_compact_ecash/src/proofs/proof_spend.rs b/common/nym_offline_compact_ecash/src/proofs/proof_spend.rs
index a130efacb2..7f5ec5d60d 100644
--- a/common/nym_offline_compact_ecash/src/proofs/proof_spend.rs
+++ b/common/nym_offline_compact_ecash/src/proofs/proof_spend.rs
@@ -728,7 +728,7 @@ mod tests {
         let cc = g1 * o_c + gamma1 * v;
 
         // compute hash of the payment info
-        let pay_info = PayInfo { info: [37u8; 32] };
+        let pay_info = PayInfo { info: [37u8; 88] };
         let rr = hash_to_scalar(pay_info.info);
 
         // evaluate the pseudorandom functions
diff --git a/common/nym_offline_compact_ecash/src/scheme/identify.rs b/common/nym_offline_compact_ecash/src/scheme/identify.rs
index c658ea0fbb..f45f298d9e 100644
--- a/common/nym_offline_compact_ecash/src/scheme/identify.rs
+++ b/common/nym_offline_compact_ecash/src/scheme/identify.rs
@@ -91,7 +91,7 @@ mod tests {
         ).unwrap();
 
         // Let's try to spend some coins
-        let pay_info1 = PayInfo { info: [6u8; 32] };
+        let pay_info1 = PayInfo { info: [6u8; 88] };
         let spend_vv = 1;
 
         let (payment1, _upd_wallet) = aggr_wallet.spend(
@@ -162,7 +162,7 @@ mod tests {
         ).unwrap();
 
         // Let's try to spend some coins
-        let pay_info1 = PayInfo { info: [6u8; 32] };
+        let pay_info1 = PayInfo { info: [6u8; 88] };
         let spend_vv = 1;
 
         let (payment1, upd_wallet) = aggr_wallet.spend(
@@ -179,7 +179,7 @@ mod tests {
             .unwrap());
 
 
-        let pay_info2 = PayInfo { info: [7u8; 32] };
+        let pay_info2 = PayInfo { info: [7u8; 88] };
         let (payment2, _) = upd_wallet.spend(
             &params,
             &verification_key,
@@ -253,7 +253,7 @@ mod tests {
         ).unwrap();
 
         // Let's try to spend some coins
-        let pay_info1 = PayInfo { info: [6u8; 32] };
+        let pay_info1 = PayInfo { info: [6u8; 88] };
         let spend_vv = 1;
 
         let (payment1, _upd_wallet) = aggr_wallet.spend(
@@ -273,7 +273,7 @@ mod tests {
         let current_l = aggr_wallet.l.get();
         aggr_wallet.l.set(current_l - 1);
 
-        let pay_info2 = PayInfo { info: [7u8; 32] };
+        let pay_info2 = PayInfo { info: [7u8; 88] };
 
         let (payment2, _) = aggr_wallet.spend(
             &params,
@@ -347,7 +347,7 @@ mod tests {
         ).unwrap();
 
         // Let's try to spend some coins
-        let pay_info1 = PayInfo { info: [6u8; 32] };
+        let pay_info1 = PayInfo { info: [6u8; 88] };
         let spend_vv = 10;
 
         let (payment1, _) = aggr_wallet.spend(
@@ -367,7 +367,7 @@ mod tests {
         let current_l = aggr_wallet.l.get();
         aggr_wallet.l.set(current_l - 10);
 
-        let pay_info2 = PayInfo { info: [7u8; 32] };
+        let pay_info2 = PayInfo { info: [7u8; 88] };
         let (payment2, _) = aggr_wallet.spend(
             &params,
             &verification_key,
diff --git a/common/nym_offline_compact_ecash/src/scheme/mod.rs b/common/nym_offline_compact_ecash/src/scheme/mod.rs
index 9848ba46fd..b151ec0629 100644
--- a/common/nym_offline_compact_ecash/src/scheme/mod.rs
+++ b/common/nym_offline_compact_ecash/src/scheme/mod.rs
@@ -311,25 +311,24 @@ pub fn compute_kappa(
 
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct PayInfo {
-    pub info: [u8; 32],
+    pub info: [u8; 88],
 }
 
-pub fn generate_payinfo(provider_pk: PublicKeyUser) -> Vec<u8>{
-    let mut rng = thread_rng();
-    let mut rbytes = [0u8; 32];
-    rng.fill(&mut rbytes);
+pub fn generate_payinfo(provider_pk: PublicKeyUser) -> PayInfo{
+    let mut info = [0u8; 88];
 
+    // Generating random bytes
+    thread_rng().fill(&mut info[..32]);
+
+    // Adding timestamp bytes
     let timestamp = Utc::now().timestamp();
-    let timestamp_bytes: [u8; 8] = timestamp.to_be_bytes();
+    info[32..40].copy_from_slice(&timestamp.to_be_bytes());
 
+    // Adding provider public key bytes
     let ppk_bytes = provider_pk.pk.to_affine().to_compressed();
+    info[40..].copy_from_slice(&ppk_bytes);
 
-    let mut payinfo = Vec::with_capacity(32 + 8 +48);
-    payinfo.extend_from_slice(&rbytes);
-    payinfo.extend_from_slice(&timestamp_bytes);
-    payinfo.extend_from_slice(&ppk_bytes);
-    
-    payinfo
+    PayInfo { info }
 }
 
 #[derive(Debug, Clone, PartialEq)]
diff --git a/common/nym_offline_compact_ecash/src/tests/e2e.rs b/common/nym_offline_compact_ecash/src/tests/e2e.rs
index 2a6f3bc45c..94182b98f7 100644
--- a/common/nym_offline_compact_ecash/src/tests/e2e.rs
+++ b/common/nym_offline_compact_ecash/src/tests/e2e.rs
@@ -70,7 +70,7 @@ fn main() -> Result<(), CompactEcashError> {
     assert_eq!(aggr_wallet, wallet);
 
     // Let's try to spend some coins
-    let pay_info = PayInfo { info: [6u8; 32] };
+    let pay_info = PayInfo { info: [6u8; 88] };
     let spend_vv = 1;
 
     let (payment, _) = aggr_wallet.spend(