From 7bb630a4b16afff8e24c4303995d2ba8e626f6ae Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Mon, 5 Mar 2018 17:27:55 -0700
Subject: [PATCH] Use correct personalization for merkle tree.

---
 src/circuit/mod.rs           | 6 +++---
 src/circuit/pedersen_hash.rs | 6 +++---
 src/pedersen_hash.rs         | 9 +++------
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/circuit/mod.rs b/src/circuit/mod.rs
index 17ee6d4..4aeec40 100644
--- a/src/circuit/mod.rs
+++ b/src/circuit/mod.rs
@@ -259,7 +259,7 @@ impl<'a, E: JubjubEngine> Circuit<E> for Spend<'a, E> {
 
             cur = pedersen_hash::pedersen_hash(
                 cs.namespace(|| "computation of pedersen hash"),
-                pedersen_hash::Personalization::MerkleTree(tree_depth - i),
+                pedersen_hash::Personalization::MerkleTree(i),
                 &preimage,
                 self.params
             )?.x; // Injective encoding
@@ -527,7 +527,7 @@ fn test_input_circuit_with_bls12_381() {
 
         assert!(cs.is_satisfied());
         assert_eq!(cs.num_constraints(), 97379);
-        assert_eq!(cs.hash(), "1c5298e7f9ec46f227d3622968b092bfbc1d15a9f45fcf4910b6edb60fe4f0f8");
+        assert_eq!(cs.hash(), "3920570cfb4c9cec807d09f996d6d0745176d50e8adea0e66709628b1dd31267");
     }
 }
 
@@ -565,6 +565,6 @@ fn test_output_circuit_with_bls12_381() {
 
         assert!(cs.is_satisfied());
         assert_eq!(cs.num_constraints(), 7827);
-        assert_eq!(cs.hash(), "a76f4ae0b3e078b6d3d44bf6d9c1d121884b30f74c97f77f114978196f4949b3");
+        assert_eq!(cs.hash(), "155b1aaf4ed4abb1af67481c7e099adafd6a7edd097926b1f9f6b68b1cbe2742");
     }
 }
diff --git a/src/circuit/pedersen_hash.rs b/src/circuit/pedersen_hash.rs
index 6daafeb..8b3d715 100644
--- a/src/circuit/pedersen_hash.rs
+++ b/src/circuit/pedersen_hash.rs
@@ -163,7 +163,7 @@ mod test {
 
                 let res = pedersen_hash(
                     cs.namespace(|| "pedersen hash"),
-                    Personalization::NoteCommitment,
+                    Personalization::MerkleTree(1),
                     &input_bools,
                     params
                 ).unwrap();
@@ -171,7 +171,7 @@ mod test {
                 assert!(cs.is_satisfied());
 
                 let expected = ::pedersen_hash::pedersen_hash::<Bls12, _>(
-                    Personalization::NoteCommitment,
+                    Personalization::MerkleTree(1),
                     input.clone().into_iter(),
                     params
                 ).into_xy();
@@ -181,7 +181,7 @@ mod test {
 
                 // Test against the output of a different personalization
                 let unexpected = ::pedersen_hash::pedersen_hash::<Bls12, _>(
-                    Personalization::AnotherPersonalization,
+                    Personalization::MerkleTree(0),
                     input.into_iter(),
                     params
                 ).into_xy();
diff --git a/src/pedersen_hash.rs b/src/pedersen_hash.rs
index 83c3965..a1eda3b 100644
--- a/src/pedersen_hash.rs
+++ b/src/pedersen_hash.rs
@@ -3,7 +3,6 @@ use pairing::*;
 
 pub enum Personalization {
     NoteCommitment,
-    AnotherPersonalization,
     MerkleTree(usize)
 }
 
@@ -11,11 +10,9 @@ impl Personalization {
     pub fn get_bits(&self) -> Vec<bool> {
         match *self {
             Personalization::NoteCommitment =>
-                vec![false, false, false, false, false, false],
-            Personalization::AnotherPersonalization =>
-                vec![false, false, false, false, false, true],
-            Personalization::MerkleTree(_) =>
-                vec![false, false, false, false, true, false],
+                vec![true, true, true, true, true, true],
+            Personalization::MerkleTree(num) =>
+                (0..6).map(|i| (num >> i) & 1 == 1).collect()
         }
     }
 }