constrain_sig() implemented, still have to test

src/schnorr_prover.rs

@@ -182,10 +182,12 @@ impl SchnorrBuilder {
         let hash_input: Vec<Target> = std::iter::once(r)
             .chain(msg.msg.iter().cloned()) 
             .collect();
-        let e: Target = builder.hash_n_to_hash_no_pad::<PoseidonHash>(
+        let hash_output: Target = builder.hash_n_to_hash_no_pad::<PoseidonHash>(
             hash_input,
         ).elements[0]; // whoops have to take mod group order;
 
+        let e: Target = Self::mod_65537(builder, hash_output);
+
         // enforce equality
         builder.connect(e, sig.e);
     }