Merkle-DAG Implementation in MATLAB

This repository contains MATLAB scripts for implementing and using a Merkle Directed Acyclic Graph (DAG) data structure.

The Merkle-DAG is a cryptographic data structure used to efficiently verify the integrity and consistency of data blocks.

About

IPFS Link

Overview

• Construct a Merkle-DAG manually or from data blocks.

• Traverse the graph structure and verify the integrity of data blocks.

• Multiple hash algorithms for computing node hashes.

  Supported algorithms from Java Security (via MATLAB)

  import java.security.MessageDigest;
  java.security.Security.getAlgorithms('MessageDigest')
  

Scripts

1. MerkleDAGNode.m

   Represents a node in the Merkle-DAG, holds data, compute hashes, and manage child nodes.

2. MerkleDAG.m

   Constructs the Merkle-DAG from data blocks, performs integrity verification, and provides traversal methods (DFS & BFS).

Example Usages

Manually Create the Merkle-DAG (Adding Nodes)

Use case: for scenarios where the DAG structure is not strictly determined by the data itself (no specific relationships/dependencies).

node1 = MerkleDAGNode([1 2 3]);     % default: SHA-256, if no hash algorithm specified
node2 = MerkleDAGNode([4 5 6]);
node3 = MerkleDAGNode([7 8 9]);

% Add children to node1 (hash recursively updated)
node1.addChild(node2);
node1.addChild(node3);

% Add another child to node2    (hash recursively updated)
node4 = MerkleDAGNode([10 11 12]);
node2.addChild(node4);

% Display the Merkle-DAG structure
DAGGraph = MerkleDAG();
DAGGraph.setRoot(node1)
DAGGraph.traverseDFS();     % Depth-First (DFS) traversal
DAGGraph.traverseBFS();     % Breadth-First (BFS) traversal

Build DAG from data blocks

Use case: automated, allowing constructing a Merkle-DAG from a matrix of data blocks.

Each row of the matrix represents a data block. The DAG is built by hashing these blocks into the graph. For scenarios where the relationships between data blocks are determined by their positions in the matrix.

dataBlocks = [      // compose data of the MerkleDAG as a matrix
    1 2 3;
    4 5 6;
    7 8 9;
    10 11 12;
    13 14 15
];

merkleDAG = MerkleDAG(dataBlocks, 'SHA-384');

% Display the Merkle-DAG structure
merkleDAG.traverseDFS();     % Depth-First (DFS) traversal
merkleDAG.traverseBFS();     % Breadth-First (BFS) traversal

Integrity Verification

The verifyBlock method checks whether a specific data block is part of the Merkle-DAG. Computes the hash of the data block and verifies it against the hashes in the DAG.

% Verify a specific data block 
dataBlockToVerify = [4 5 6];
merkleDAG.verifyBlock(dataBlockToVerify);