From 012598880cf69a6a4d4d495c78e40ab4abb4eb39 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 22 Nov 2014 15:44:43 +0100
Subject: [PATCH] Implement test for merkle tree malleability in
CPartialMerkleTree
This is a check that is mentioned in BIP 37, but never implemented in the
reference code. As Bitcoin Core so far never decodes partial merkle trees,
this is not a problem. But perhaps others use the code as a reference.
---
src/merkleblock.cpp | 10 ++++++++--
src/test/pmt_tests.cpp | 11 +++++++++++
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/src/merkleblock.cpp b/src/merkleblock.cpp
index 8618e355d..0500cfde8 100644
--- a/src/merkleblock.cpp
+++ b/src/merkleblock.cpp
@@ -93,10 +93,16 @@ uint256 CPartialMerkleTree::TraverseAndExtract(int height, unsigned int pos, uns
} else {
// otherwise, descend into the subtrees to extract matched txids and hashes
uint256 left = TraverseAndExtract(height-1, pos*2, nBitsUsed, nHashUsed, vMatch), right;
- if (pos*2+1 < CalcTreeWidth(height-1))
+ if (pos*2+1 < CalcTreeWidth(height-1)) {
right = TraverseAndExtract(height-1, pos*2+1, nBitsUsed, nHashUsed, vMatch);
- else
+ if (right == left) {
+ // If the left and right branch should never be identical as the transaction
+ // hashes covered by them must be unique.
+ fBad = true;
+ }
+ } else {
right = left;
+ }
// and combine them before returning
return Hash(BEGIN(left), END(left), BEGIN(right), END(right));
}
diff --git a/src/test/pmt_tests.cpp b/src/test/pmt_tests.cpp
index 3b535a84f..eea5b0af4 100644
--- a/src/test/pmt_tests.cpp
+++ b/src/test/pmt_tests.cpp
@@ -10,6 +10,7 @@
#include <vector>
+#include <boost/assign/list_of.hpp>
#include <boost/test/unit_test.hpp>
using namespace std;
@@ -104,4 +105,14 @@ BOOST_AUTO_TEST_CASE(pmt_test1)
}
}
+BOOST_AUTO_TEST_CASE(pmt_malleability)
+{
+ std::vector<uint256> vTxid = boost::assign::list_of(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(9)(10);
+ std::vector<bool> vMatch = boost::assign::list_of(false)(false)(false)(false)(false)(false)(false)(false)(false)(true)(true)(false);
+
+ CPartialMerkleTree tree(vTxid, vMatch);
+ std::vector<uint256> vTxid2;
+ BOOST_CHECK(tree.ExtractMatches(vTxid) == 0);
+}
+
BOOST_AUTO_TEST_SUITE_END()