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Remove the Merkle tree hash function's fixed point.

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This commit is contained in:
Taylor Hornby
2016-05-04 09:15:14 -06:00
parent 9e387120eb
commit bf2e3122ac
8 changed files with 251 additions and 132 deletions
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42
src/zcash/IncrementalMerkleTree.cpp
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@@ -10,11 +10,6 @@ namespace libzcash {
SHA256Compress SHA256Compress::combine(const SHA256Compress& a, const SHA256Compress& b)
{
// This is a performance optimization.
if (a.IsNull() && b.IsNull()) {
return a;
}
SHA256Compress res = SHA256Compress();
CSHA256 hasher;
@@ -25,27 +20,34 @@ SHA256Compress SHA256Compress::combine(const SHA256Compress& a, const SHA256Comp
return res;
}
template <typename Hash>
template <size_t Depth, typename Hash>
class PathFiller {
private:
std::deque<Hash> queue;
static EmptyMerkleRoots<Depth, Hash> emptyroots;
public:
PathFiller() : queue() { }
PathFiller(std::deque<Hash> queue) : queue(queue) { }
Hash next() {
Hash next(size_t depth) {
if (queue.size() > 0) {
Hash h = queue.front();
queue.pop_front();
return h;
} else {
return Hash();
return emptyroots.empty_root(depth);
}
}
};
template<size_t Depth, typename Hash>
EmptyMerkleRoots<Depth, Hash> PathFiller<Depth, Hash>::emptyroots;
template<size_t Depth, typename Hash>
EmptyMerkleRoots<Depth, Hash> IncrementalMerkleTree<Depth, Hash>::emptyroots;
template<size_t Depth, typename Hash>
void IncrementalMerkleTree<Depth, Hash>::wfcheck() const {
if (parents.size() >= Depth) {
@@ -132,7 +134,7 @@ bool IncrementalMerkleTree<Depth, Hash>::is_complete(size_t depth) const {
template<size_t Depth, typename Hash>
size_t IncrementalMerkleTree<Depth, Hash>::next_depth(size_t skip) const {
if (!left) {
if (skip) {
if (skip) {
skip--;
} else {
return 0;
@@ -140,7 +142,7 @@ size_t IncrementalMerkleTree<Depth, Hash>::next_depth(size_t skip) const {
}
if (!right) {
if (skip) {
if (skip) {
skip--;
} else {
return 0;
@@ -168,10 +170,10 @@ size_t IncrementalMerkleTree<Depth, Hash>::next_depth(size_t skip) const {
template<size_t Depth, typename Hash>
Hash IncrementalMerkleTree<Depth, Hash>::root(size_t depth,
std::deque<Hash> filler_hashes) const {
PathFiller<Hash> filler(filler_hashes);
PathFiller<Depth, Hash> filler(filler_hashes);
Hash combine_left = left ? *left : filler.next();
Hash combine_right = right ? *right : filler.next();
Hash combine_left = left ? *left : filler.next(0);
Hash combine_right = right ? *right : filler.next(0);
Hash root = Hash::combine(combine_left, combine_right);
@@ -181,7 +183,7 @@ Hash IncrementalMerkleTree<Depth, Hash>::root(size_t depth,
if (parent) {
root = Hash::combine(*parent, root);
} else {
root = Hash::combine(root, filler.next());
root = Hash::combine(root, filler.next(d));
}
d++;
@@ -190,7 +192,7 @@ Hash IncrementalMerkleTree<Depth, Hash>::root(size_t depth,
// We may not have parents for ancestor trees, so we fill
// the rest in here.
while (d < depth) {
root = Hash::combine(root, filler.next());
root = Hash::combine(root, filler.next(d));
d++;
}
@@ -205,7 +207,7 @@ MerklePath IncrementalMerkleTree<Depth, Hash>::path(std::deque<Hash> filler_hash
throw std::runtime_error("can't create an authentication path for the beginning of the tree");
}
PathFiller<Hash> filler(filler_hashes);
PathFiller<Depth, Hash> filler(filler_hashes);
std::vector<Hash> path;
std::vector<bool> index;
@@ -215,7 +217,7 @@ MerklePath IncrementalMerkleTree<Depth, Hash>::path(std::deque<Hash> filler_hash
path.push_back(*left);
} else {
index.push_back(false);
path.push_back(filler.next());
path.push_back(filler.next(0));
}
size_t d = 1;
@@ -226,7 +228,7 @@ MerklePath IncrementalMerkleTree<Depth, Hash>::path(std::deque<Hash> filler_hash
path.push_back(*parent);
} else {
index.push_back(false);
path.push_back(filler.next());
path.push_back(filler.next(d));
}
d++;
@@ -234,7 +236,7 @@ MerklePath IncrementalMerkleTree<Depth, Hash>::path(std::deque<Hash> filler_hash
while (d < Depth) {
index.push_back(false);
path.push_back(filler.next());
path.push_back(filler.next(d));
d++;
}