Browse Source
This switches the Merkle tree logic for blocks to one that runs in constant (small) space. The old code is moved to tests, and a new test is added that for various combinations of block sizes, transaction positions to compute a branch for, and mutations: * Verifies that the old code and new code agree for the Merkle root. * Verifies that the old code and new code agree for the Merkle branch. * Verifies that the computed Merkle branch is valid. * Verifies that mutations don't change the Merkle root. * Verifies that mutations are correctly detected.0.13
Pieter Wuille
9 years ago
12 changed files with 182 additions and 75 deletions
@ -0,0 +1,136 @@
@@ -0,0 +1,136 @@
|
||||
// Copyright (c) 2015 The Bitcoin Core developers
|
||||
// Distributed under the MIT software license, see the accompanying
|
||||
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
|
||||
|
||||
#include "consensus/merkle.h" |
||||
#include "test/test_bitcoin.h" |
||||
#include "random.h" |
||||
|
||||
#include <boost/test/unit_test.hpp> |
||||
|
||||
BOOST_FIXTURE_TEST_SUITE(merkle_tests, TestingSetup) |
||||
|
||||
// Older version of the merkle root computation code, for comparison.
|
||||
static uint256 BlockBuildMerkleTree(const CBlock& block, bool* fMutated, std::vector<uint256>& vMerkleTree) |
||||
{ |
||||
vMerkleTree.clear(); |
||||
vMerkleTree.reserve(block.vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes.
|
||||
for (std::vector<CTransaction>::const_iterator it(block.vtx.begin()); it != block.vtx.end(); ++it) |
||||
vMerkleTree.push_back(it->GetHash()); |
||||
int j = 0; |
||||
bool mutated = false; |
||||
for (int nSize = block.vtx.size(); nSize > 1; nSize = (nSize + 1) / 2) |
||||
{ |
||||
for (int i = 0; i < nSize; i += 2) |
||||
{ |
||||
int i2 = std::min(i+1, nSize-1); |
||||
if (i2 == i + 1 && i2 + 1 == nSize && vMerkleTree[j+i] == vMerkleTree[j+i2]) { |
||||
// Two identical hashes at the end of the list at a particular level.
|
||||
mutated = true; |
||||
} |
||||
vMerkleTree.push_back(Hash(vMerkleTree[j+i].begin(), vMerkleTree[j+i].end(), |
||||
vMerkleTree[j+i2].begin(), vMerkleTree[j+i2].end())); |
||||
} |
||||
j += nSize; |
||||
} |
||||
if (fMutated) { |
||||
*fMutated = mutated; |
||||
} |
||||
return (vMerkleTree.empty() ? uint256() : vMerkleTree.back()); |
||||
} |
||||
|
||||
// Older version of the merkle branch computation code, for comparison.
|
||||
static std::vector<uint256> BlockGetMerkleBranch(const CBlock& block, const std::vector<uint256>& vMerkleTree, int nIndex) |
||||
{ |
||||
std::vector<uint256> vMerkleBranch; |
||||
int j = 0; |
||||
for (int nSize = block.vtx.size(); nSize > 1; nSize = (nSize + 1) / 2) |
||||
{ |
||||
int i = std::min(nIndex^1, nSize-1); |
||||
vMerkleBranch.push_back(vMerkleTree[j+i]); |
||||
nIndex >>= 1; |
||||
j += nSize; |
||||
} |
||||
return vMerkleBranch; |
||||
} |
||||
|
||||
static inline int ctz(uint32_t i) { |
||||
if (i == 0) return 0; |
||||
int j = 0; |
||||
while (!(i & 1)) { |
||||
j++; |
||||
i >>= 1; |
||||
} |
||||
return j; |
||||
} |
||||
|
||||
BOOST_AUTO_TEST_CASE(merkle_test) |
||||
{ |
||||
for (int i = 0; i < 32; i++) { |
||||
// Try 32 block sizes: all sizes from 0 to 16 inclusive, and then 15 random sizes.
|
||||
int ntx = (i <= 16) ? i : 17 + (insecure_rand() % 4000); |
||||
// Try up to 3 mutations.
|
||||
for (int mutate = 0; mutate <= 3; mutate++) { |
||||
int duplicate1 = mutate >= 1 ? 1 << ctz(ntx) : 0; // The last how many transactions to duplicate first.
|
||||
if (duplicate1 >= ntx) break; // Duplication of the entire tree results in a different root (it adds a level).
|
||||
int ntx1 = ntx + duplicate1; // The resulting number of transactions after the first duplication.
|
||||
int duplicate2 = mutate >= 2 ? 1 << ctz(ntx1) : 0; // Likewise for the second mutation.
|
||||
if (duplicate2 >= ntx1) break; |
||||
int ntx2 = ntx1 + duplicate2; |
||||
int duplicate3 = mutate >= 3 ? 1 << ctz(ntx2) : 0; // And for the the third mutation.
|
||||
if (duplicate3 >= ntx2) break; |
||||
int ntx3 = ntx2 + duplicate3; |
||||
// Build a block with ntx different transactions.
|
||||
CBlock block; |
||||
block.vtx.resize(ntx); |
||||
for (int j = 0; j < ntx; j++) { |
||||
CMutableTransaction mtx; |
||||
mtx.nLockTime = j; |
||||
block.vtx[j] = mtx; |
||||
} |
||||
// Compute the root of the block before mutating it.
|
||||
bool unmutatedMutated = false; |
||||
uint256 unmutatedRoot = BlockMerkleRoot(block, &unmutatedMutated); |
||||
BOOST_CHECK(unmutatedMutated == false); |
||||
// Optionally mutate by duplicating the last transactions, resulting in the same merkle root.
|
||||
block.vtx.resize(ntx3); |
||||
for (int j = 0; j < duplicate1; j++) { |
||||
block.vtx[ntx + j] = block.vtx[ntx + j - duplicate1]; |
||||
} |
||||
for (int j = 0; j < duplicate2; j++) { |
||||
block.vtx[ntx1 + j] = block.vtx[ntx1 + j - duplicate2]; |
||||
} |
||||
for (int j = 0; j < duplicate3; j++) { |
||||
block.vtx[ntx2 + j] = block.vtx[ntx2 + j - duplicate3]; |
||||
} |
||||
// Compute the merkle root and merkle tree using the old mechanism.
|
||||
bool oldMutated = false; |
||||
std::vector<uint256> merkleTree; |
||||
uint256 oldRoot = BlockBuildMerkleTree(block, &oldMutated, merkleTree); |
||||
// Compute the merkle root using the new mechanism.
|
||||
bool newMutated = false; |
||||
uint256 newRoot = BlockMerkleRoot(block, &newMutated); |
||||
BOOST_CHECK(oldRoot == newRoot); |
||||
BOOST_CHECK(newRoot == unmutatedRoot); |
||||
BOOST_CHECK((newRoot == uint256()) == (ntx == 0)); |
||||
BOOST_CHECK(oldMutated == newMutated); |
||||
BOOST_CHECK(newMutated == !!mutate); |
||||
// If no mutation was done (once for every ntx value), try up to 16 branches.
|
||||
if (mutate == 0) { |
||||
for (int loop = 0; loop < std::min(ntx, 16); loop++) { |
||||
// If ntx <= 16, try all branches. Otherise, try 16 random ones.
|
||||
int mtx = loop; |
||||
if (ntx > 16) { |
||||
mtx = insecure_rand() % ntx; |
||||
} |
||||
std::vector<uint256> newBranch = BlockMerkleBranch(block, mtx); |
||||
std::vector<uint256> oldBranch = BlockGetMerkleBranch(block, merkleTree, mtx); |
||||
BOOST_CHECK(oldBranch == newBranch); |
||||
BOOST_CHECK(ComputeMerkleRootFromBranch(block.vtx[mtx].GetHash(), newBranch, mtx) == oldRoot); |
||||
} |
||||
} |
||||
} |
||||
} |
||||
} |
||||
|
||||
BOOST_AUTO_TEST_SUITE_END() |
||||
Loading…
Reference in new issue