dustinest/merkletree

Simple Merkle tree implementation

The purpose of this implementation is to hash and sign each type of tree node using algorithms algorithms.

Available types are:

• LeafNode - the node which usually contains the data
• TreeNode - the tree node between leaf node and top node
• TopNode - top node - usually needs to be signed

To check the node type:

node.is(LeafNode.class); or node.as(LeafNode.class).isPresent();

To get parent of the leaf node for instance:

LeafNode parentNode = node.as(LeafNode.class).map(LeafNode::getParent).orElse(null);

https://en.wikipedia.org/wiki/Merkle_tree

Initiate the merkle tree configuratino

See MerkleTreeConfiguration constructors First let's create a function to transform byte to String signature

For instance, when you have local methods:

To hash the leaf data

    private static byte[] leafNodeHasher(String data);

To combine two byte arrays (hash the tree and top node

    private static byte[] fromByteArray(byte[] left, byte[] right);

Then you can initiate the configuration:

MerkleTreeConfiguration<byte[], byte[], String> merkleTreeConfiguration = new MerkleTreeConfiguration<byte[], byte[], String>(MerkleTreeBuilderTest::leafNodeHasher, MerkleTreeBuilderTest::fromByteArray);

Create the builder:

MerkleTreeBuilder<byte[], byte[], String> merkleTreeBuilder = merkleTreeConfiguration.getBuilder();

Next add data:

merkleTreeBuilder.addDataBlock("lorem");
merkleTreeBuilder.addDataBlock("ipsum");
merkleTreeBuilder.addDataBlock("est");
//etc..

When you are ready to build the tree just call the method below. Note that it will clean up data added

List<LeafNode<byte[]>> result = merkleTreeBuilder.buildTree();

Check out the tests for use cases and acessing the nodes.