Use const for generating H

crates/lox-library/src/proto/positive_report.rs

@@ -30,6 +30,7 @@ use super::super::cred;
 use super::super::scalar_u32;
 use super::super::{BridgeAuth, IssuerPubKey};
 use super::super::{CMZ_A, CMZ_A_TABLE};
+pub const H_GENERATOR_STRING: &str = "PR Generator H for ";
 
 #[derive(Serialize, Deserialize)]
 pub struct Request {
@@ -44,7 +45,7 @@ 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 +87,13 @@ 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!("{}{}", H_GENERATOR_STRING, date).as_bytes(),
     );
     let Htable: RistrettoBasepointTable = RistrettoBasepointTable::create(&H);
 
@@ -223,7 +224,7 @@ pub fn request(lox_cred: &cred::Lox, lox_pub: &IssuerPubKey) -> Result<Request,
         CInvRemain,
         CBlockages,
         CQ,
-        H,
+        date,
         BP,
         CGsq,
         piUser,
@@ -234,8 +235,11 @@ 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!("{}{}", H_GENERATOR_STRING, req.date).as_bytes(),
+        );
 
-        if req.P.is_identity() || req.H.is_identity() {
+        if req.P.is_identity() {
             return Err(ProofError::VerificationFailure);
         }
 
@@ -275,7 +279,7 @@ 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(),