From 2b002a7e60bd3fd037f2b4352bb3d4794df6b21d Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Sat, 14 Apr 2018 22:33:41 -0600
Subject: [PATCH] Add implementation of Sapling merkle tree

---
 src/zcash/IncrementalMerkleTree.cpp | 33 +++++++++++++++++++++++++++++
 src/zcash/IncrementalMerkleTree.hpp | 20 +++++++++++++++++
 src/zcash/Zcash.h                   |  2 ++
 3 files changed, 55 insertions(+)

diff --git a/src/zcash/IncrementalMerkleTree.cpp b/src/zcash/IncrementalMerkleTree.cpp
index 3101cf3f3..f8d5fad61 100644
--- a/src/zcash/IncrementalMerkleTree.cpp
+++ b/src/zcash/IncrementalMerkleTree.cpp
@@ -5,9 +5,36 @@
 #include "zcash/IncrementalMerkleTree.hpp"
 #include "crypto/sha256.h"
 #include "zcash/util.h"
+#include "librustzcash.h"
 
 namespace libzcash {
 
+PedersenHash PedersenHash::combine(
+    const PedersenHash& a,
+    const PedersenHash& b,
+    size_t depth
+)
+{
+    PedersenHash res = PedersenHash();
+
+    librustzcash_merkle_hash(
+        depth,
+        a.begin(),
+        b.begin(),
+        res.begin()
+    );
+
+    return res;
+}
+
+PedersenHash PedersenHash::uncommitted() {
+    PedersenHash res = PedersenHash();
+
+    librustzcash_tree_uncommitted(res.begin());
+
+    return res;
+}
+
 SHA256Compress SHA256Compress::combine(
     const SHA256Compress& a,
     const SHA256Compress& b,
@@ -327,4 +354,10 @@ template class IncrementalMerkleTree<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, SHA2
 template class IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH, SHA256Compress>;
 template class IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, SHA256Compress>;
 
+template class IncrementalMerkleTree<SAPLING_INCREMENTAL_MERKLE_TREE_DEPTH, PedersenHash>;
+template class IncrementalMerkleTree<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, PedersenHash>;
+
+template class IncrementalWitness<SAPLING_INCREMENTAL_MERKLE_TREE_DEPTH, PedersenHash>;
+template class IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, PedersenHash>;
+
 } // end namespace `libzcash`
diff --git a/src/zcash/IncrementalMerkleTree.hpp b/src/zcash/IncrementalMerkleTree.hpp
index ce536fec4..fc476cd29 100644
--- a/src/zcash/IncrementalMerkleTree.hpp
+++ b/src/zcash/IncrementalMerkleTree.hpp
@@ -224,6 +224,20 @@ public:
     }
 };
 
+class PedersenHash : public uint256 {
+public:
+    PedersenHash() : uint256() {}
+    PedersenHash(uint256 contents) : uint256(contents) { }
+
+    static PedersenHash combine(
+        const PedersenHash& a,
+        const PedersenHash& b,
+        size_t depth
+    );
+
+    static PedersenHash uncommitted();
+};
+
 template<size_t Depth, typename Hash>
 EmptyMerkleRoots<Depth, Hash> IncrementalMerkleTree<Depth, Hash>::emptyroots;
 
@@ -235,4 +249,10 @@ typedef libzcash::IncrementalMerkleTree<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, l
 typedef libzcash::IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH, libzcash::SHA256Compress> ZCIncrementalWitness;
 typedef libzcash::IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, libzcash::SHA256Compress> ZCTestingIncrementalWitness;
 
+typedef libzcash::IncrementalMerkleTree<SAPLING_INCREMENTAL_MERKLE_TREE_DEPTH, libzcash::PedersenHash> ZCSaplingIncrementalMerkleTree;
+typedef libzcash::IncrementalMerkleTree<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, libzcash::PedersenHash> ZCSaplingTestingIncrementalMerkleTree;
+
+typedef libzcash::IncrementalWitness<SAPLING_INCREMENTAL_MERKLE_TREE_DEPTH, libzcash::PedersenHash> ZCSaplingIncrementalWitness;
+typedef libzcash::IncrementalWitness<INCREMENTAL_MERKLE_TREE_DEPTH_TESTING, libzcash::PedersenHash> ZCSaplingTestingIncrementalWitness;
+
 #endif /* ZC_INCREMENTALMERKLETREE_H_ */
diff --git a/src/zcash/Zcash.h b/src/zcash/Zcash.h
index 9e6684475..bb805eef5 100644
--- a/src/zcash/Zcash.h
+++ b/src/zcash/Zcash.h
@@ -6,6 +6,8 @@
 #define INCREMENTAL_MERKLE_TREE_DEPTH 29
 #define INCREMENTAL_MERKLE_TREE_DEPTH_TESTING 4
 
+#define SAPLING_INCREMENTAL_MERKLE_TREE_DEPTH 32
+
 #define ZC_NOTEPLAINTEXT_LEADING 1
 #define ZC_V_SIZE 8
 #define ZC_RHO_SIZE 32