public class PartialMerkleTree
Building and verification of Partial Merkle Tree. Partial Merkle Tree is a minimal tree needed to check that a given set of leaves belongs to a full Merkle Tree.
Example of Merkle tree with 5 leaves.
h15
/ \
h14 h55
/ \ / \
h12 h34 h50 h00
/ \ / \ / \ / \
l1 l2 l3 l4 l5 0 0 0l* denote hashes of leaves, h* - hashes of nodes below. 0 denotes zero hash, we use it to pad not full binary trees, so the number of leaves is always a power of 2.
Example of Partial tree based on the tree above.
___
/ \
_ _
/ \ / \
h12 _ _ h00
/ \ / \
I3 l4 I5 0We want to check l3 and l5 - now turned into IncudedLeaf (I3 and I5 above). To verify that these two leaves belong to the tree with a hash root h15 we need to provide a Merkle branch (or partial tree). In our case we need hashes: h12, l4, 0 and h00. Verification is done by hashing the partial tree to obtain the root and checking it against the obtained h15 hash. Additionally we store included hashes used in calculation and compare them to leaves hashes we got (there can be a difference in obtained leaves ordering - that's why it's a set comparison not hashing leaves into a tree). If both equalities hold, we can assume that l3 and l5 belong to the transaction with root h15.
public PartialMerkleTree(@NotNull
net.corda.core.crypto.PartialMerkleTree.PartialTree root)
Building and verification of Partial Merkle Tree. Partial Merkle Tree is a minimal tree needed to check that a given set of leaves belongs to a full Merkle Tree.
Example of Merkle tree with 5 leaves.
h15
/ \
h14 h55
/ \ / \
h12 h34 h50 h00
/ \ / \ / \ / \
l1 l2 l3 l4 l5 0 0 0l* denote hashes of leaves, h* - hashes of nodes below. 0 denotes zero hash, we use it to pad not full binary trees, so the number of leaves is always a power of 2.
Example of Partial tree based on the tree above.
___
/ \
_ _
/ \ / \
h12 _ _ h00
/ \ / \
I3 l4 I5 0We want to check l3 and l5 - now turned into IncudedLeaf (I3 and I5 above). To verify that these two leaves belong to the tree with a hash root h15 we need to provide a Merkle branch (or partial tree). In our case we need hashes: h12, l4, 0 and h00. Verification is done by hashing the partial tree to obtain the root and checking it against the obtained h15 hash. Additionally we store included hashes used in calculation and compare them to leaves hashes we got (there can be a difference in obtained leaves ordering - that's why it's a set comparison not hashing leaves into a tree). If both equalities hold, we can assume that l3 and l5 belong to the transaction with root h15.
public boolean verify(@NotNull
SecureHash merkleRootHash,
@NotNull
java.util.List<? extends net.corda.core.crypto.SecureHash> hashesToCheck)
Function to verify a class PartialMerkleTree against an input Merkle root and a list of leaves.
The tree should only contain the leaves defined in hashesToCheck.
merkleRootHash - Hash that should be checked for equality with root calculated from this partial tree.hashesToCheck - List of included leaves hashes that should be found in this partial tree.class PartialMerkleTree,
hashesToCheck@CordaInternal public int leafIndex(@NotNull SecureHash leaf)
Method to return the index of the input leaf in the partial Merkle tree structure.
leaf - the component hash to check.MerkleTreeException - if the provided hash is not in the tree.@NotNull public net.corda.core.crypto.PartialMerkleTree.PartialTree getRoot()