From 848d5793a1c6d18e5ac488e199fe2f0f4fd779c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Friedger=20M=C3=BCffke?= <mail@friedger.de>
Date: Thu, 22 Jul 2021 13:21:00 +0200
Subject: [PATCH 1/2] add tests for all bitcoin tree leaves

---
 test/merkletree.test.js | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/test/merkletree.test.js b/test/merkletree.test.js
index c5de669..d6ba675 100644
--- a/test/merkletree.test.js
+++ b/test/merkletree.test.js
@@ -351,7 +351,7 @@ test('solidity keccak256 with duplicate leaves', t => {
 })
 
 test('sha-256 with option.isBitcoinTree', t => {
-  t.plan(2)
+  t.plan(100)
 
   /* Derived from:
    * http://www.righto.com/2014/02/bitcoin-mining-hard-way-algorithms.html
@@ -464,9 +464,10 @@ test('sha-256 with option.isBitcoinTree', t => {
   const root = Buffer.from('871714dcbae6c8193a2bb9b2a69fe1c0440399f38d94b3a0f1b447275a29978a', 'hex')
   t.equal(tree.getRoot().toString('hex'), root.toString('hex'))
 
-  const proof_0 = tree.getProof(leaves[0])
-
-  t.true(tree.verify(proof_0, leaves[0], root))
+  for (let i = 0; i < leaves.length; i++) {
+    const proof_0 = tree.getProof(leaves[i])
+    t.true(tree.verify(proof_0, leaves[i], root), 'proof verification for ' + i)
+  }
 })
 
 test('keccak256 - hex strings', t => {

From 95624eeb5bb916948b656ded0ba130bd4957d913 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Friedger=20M=C3=BCffke?= <mail@friedger.de>
Date: Thu, 22 Jul 2021 14:46:37 +0200
Subject: [PATCH 2/2] fix bitcoinTree edge case (#38)

---
 src/MerkleTree.ts | 54 ++++++++++++++++-------------------------------
 1 file changed, 18 insertions(+), 36 deletions(-)

diff --git a/src/MerkleTree.ts b/src/MerkleTree.ts
index 30c2079..6daa5d5 100644
--- a/src/MerkleTree.ts
+++ b/src/MerkleTree.ts
@@ -396,46 +396,28 @@ export class MerkleTree extends Base {
       return []
     }
 
-    if (this.isBitcoinTree && index === (this.leaves.length - 1)) {
-      // Proof Generation for Bitcoin Trees
+    for (let i = 0; i < this.layers.length; i++) {
+      const layer = this.layers[i]
+      const isRightNode = index % 2
+      const pairIndex = (isRightNode ? index - 1
+        : this.isBitcoinTree && index === layer.length - 1 && i < this.layers.length - 1
+          // Proof Generation for Bitcoin Trees
+          ? index
+          // Proof Generation for Non-Bitcoin Trees
+          : index + 1)
 
-      for (let i = 0; i < this.layers.length - 1; i++) {
-        const layer = this.layers[i]
-        const isRightNode = index % 2
-        const pairIndex = (isRightNode ? index - 1 : index)
-
-        if (pairIndex < layer.length) {
-          proof.push({
-            data: layer[pairIndex]
-          })
-        }
-
-        // set index to parent index
-        index = (index / 2) | 0
+      if (pairIndex < layer.length) {
+        proof.push({
+          position: isRightNode ? 'left' : 'right',
+          data: layer[pairIndex]
+        })
       }
 
-      return proof
-    } else {
-      // Proof Generation for Non-Bitcoin Trees
-
-      for (let i = 0; i < this.layers.length; i++) {
-        const layer = this.layers[i]
-        const isRightNode = index % 2
-        const pairIndex = (isRightNode ? index - 1 : index + 1)
-
-        if (pairIndex < layer.length) {
-          proof.push({
-            position: isRightNode ? 'left' : 'right',
-            data: layer[pairIndex]
-          })
-        }
-
-        // set index to parent index
-        index = (index / 2) | 0
-      }
-
-      return proof
+      // set index to parent index
+      index = (index / 2) | 0
     }
+
+    return proof
   }
 
   /**