From af68c8818dd3ab252eb80296e6a492a45f03146b Mon Sep 17 00:00:00 2001
From: Vecna <vvecna@uwaterloo.ca>
Date: Mon, 26 Feb 2024 17:37:56 -0500
Subject: [PATCH] Have LA recompute H rather than accepting it from user

---
 crates/lox-library/src/proto/positive_report.rs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/crates/lox-library/src/proto/positive_report.rs b/crates/lox-library/src/proto/positive_report.rs
index 26b31d5..6e36b09 100644
--- a/crates/lox-library/src/proto/positive_report.rs
+++ b/crates/lox-library/src/proto/positive_report.rs
@@ -44,7 +44,7 @@ pub struct Request {
     CQ: RistrettoPoint,
 
     // Fields for proving which bucket we have
-    pub H: RistrettoPoint,
+    pub date: u32, // date is used to compute H
     pub BP: RistrettoPoint,
 
     // Fields for proving 3 <= trust_level <= 4
@@ -86,13 +86,13 @@ pub fn request(lox_cred: &cred::Lox, lox_pub: &IssuerPubKey) -> Result<Request,
     let Atable: &RistrettoBasepointTable = &CMZ_A_TABLE;
 
     // TODO: Where should this go? For efficiency, this should probably be global
-    let today: u32 = time::OffsetDateTime::now_utc()
+    let date: u32 = time::OffsetDateTime::now_utc()
         .date()
         .to_julian_day()
         .try_into()
         .unwrap();
     let H: RistrettoPoint = RistrettoPoint::hash_from_bytes::<Sha512>(
-        format!("PR Generator H for {}", today).as_bytes(),
+        format!("PR Generator H for {}", date).as_bytes(),
     );
     let Htable: RistrettoBasepointTable = RistrettoBasepointTable::create(&H);
 
@@ -223,7 +223,7 @@ pub fn request(lox_cred: &cred::Lox, lox_pub: &IssuerPubKey) -> Result<Request,
         CInvRemain,
         CBlockages,
         CQ,
-        H,
+        date,
         BP,
         CGsq,
         piUser,
@@ -234,8 +234,11 @@ impl BridgeAuth {
     /// Receive a positive report request
     pub fn handle_positive_report(&mut self, req: Request) -> Result<(), ProofError> {
         let A: &RistrettoPoint = &CMZ_A;
+        let H: RistrettoPoint = RistrettoPoint::hash_from_bytes::<Sha512>(
+            format!("PR Generator H for {}", req.date).as_bytes(),
+        );
 
-        if req.P.is_identity() || req.H.is_identity() {
+        if req.P.is_identity() {
             return Err(ProofError::VerificationFailure);
         }
 
@@ -275,7 +278,7 @@ impl BridgeAuth {
                 Xsince: &self.lox_pub.X[4].compress(),
                 Xinvremain: &self.lox_pub.X[5].compress(),
                 Xblockages: &self.lox_pub.X[6].compress(),
-                H: &req.H.compress(),
+                H: &H.compress(),
                 BP: &req.BP.compress(),
                 CG: &CG.compress(),
                 CGsq: &req.CGsq.compress(),