diff options
Diffstat (limited to 'src/core.cpp')
| -rw-r--r-- | src/core.cpp | 65 |
1 files changed, 51 insertions, 14 deletions
diff --git a/src/core.cpp b/src/core.cpp index e52327ba8e..380b1c38e0 100644 --- a/src/core.cpp +++ b/src/core.cpp @@ -43,7 +43,7 @@ std::string CTxIn::ToString() const return str; } -CTxOut::CTxOut(int64_t nValueIn, CScript scriptPubKeyIn) +CTxOut::CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn) { nValue = nValueIn; scriptPubKey = scriptPubKeyIn; @@ -59,7 +59,7 @@ std::string CTxOut::ToString() const return strprintf("CTxOut(nValue=%d.%08d, scriptPubKey=%s)", nValue / COIN, nValue % COIN, scriptPubKey.ToString().substr(0,30)); } -CFeeRate::CFeeRate(int64_t nFeePaid, size_t nSize) +CFeeRate::CFeeRate(const CAmount& nFeePaid, size_t nSize) { if (nSize > 0) nSatoshisPerK = nFeePaid*1000/nSize; @@ -67,9 +67,9 @@ CFeeRate::CFeeRate(int64_t nFeePaid, size_t nSize) nSatoshisPerK = 0; } -int64_t CFeeRate::GetFee(size_t nSize) const +CAmount CFeeRate::GetFee(size_t nSize) const { - int64_t nFee = nSatoshisPerK*nSize / 1000; + CAmount nFee = nSatoshisPerK*nSize / 1000; if (nFee == 0 && nSatoshisPerK > 0) nFee = nSatoshisPerK; @@ -110,9 +110,9 @@ CTransaction& CTransaction::operator=(const CTransaction &tx) { return *this; } -int64_t CTransaction::GetValueOut() const +CAmount CTransaction::GetValueOut() const { - int64_t nValueOut = 0; + CAmount nValueOut = 0; BOOST_FOREACH(const CTxOut& txout, vout) { nValueOut += txout.nValue; @@ -224,29 +224,66 @@ uint256 CBlockHeader::GetHash() const return Hash(BEGIN(nVersion), END(nNonce)); } -uint256 CBlock::BuildMerkleTree() const +uint256 CBlock::BuildMerkleTree(bool* fMutated) const { - // WARNING! If you're reading this because you're learning about crypto - // and/or designing a new system that will use merkle trees, keep in mind - // that the following merkle tree algorithm has a serious flaw related to - // duplicate txids, resulting in a vulnerability. (CVE-2012-2459) Bitcoin - // has since worked around the flaw, but for new applications you should - // use something different; don't just copy-and-paste this code without - // understanding the problem first. + /* WARNING! If you're reading this because you're learning about crypto + and/or designing a new system that will use merkle trees, keep in mind + that the following merkle tree algorithm has a serious flaw related to + duplicate txids, resulting in a vulnerability (CVE-2012-2459). + + The reason is that if the number of hashes in the list at a given time + is odd, the last one is duplicated before computing the next level (which + is unusual in Merkle trees). This results in certain sequences of + transactions leading to the same merkle root. For example, these two + trees: + + A A + / \ / \ + B C B C + / \ | / \ / \ + D E F D E F F + / \ / \ / \ / \ / \ / \ / \ + 1 2 3 4 5 6 1 2 3 4 5 6 5 6 + + for transaction lists [1,2,3,4,5,6] and [1,2,3,4,5,6,5,6] (where 5 and + 6 are repeated) result in the same root hash A (because the hash of both + of (F) and (F,F) is C). + + The vulnerability results from being able to send a block with such a + transaction list, with the same merkle root, and the same block hash as + the original without duplication, resulting in failed validation. If the + receiving node proceeds to mark that block as permanently invalid + however, it will fail to accept further unmodified (and thus potentially + valid) versions of the same block. We defend against this by detecting + the case where we would hash two identical hashes at the end of the list + together, and treating that identically to the block having an invalid + merkle root. Assuming no double-SHA256 collisions, this will detect all + known ways of changing the transactions without affecting the merkle + root. + */ vMerkleTree.clear(); + vMerkleTree.reserve(vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes. BOOST_FOREACH(const CTransaction& tx, vtx) vMerkleTree.push_back(tx.GetHash()); int j = 0; + bool mutated = false; for (int nSize = 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(BEGIN(vMerkleTree[j+i]), END(vMerkleTree[j+i]), BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2]))); } j += nSize; } + if (fMutated) { + *fMutated = mutated; + } return (vMerkleTree.empty() ? 0 : vMerkleTree.back()); } |