Understanding Merkle Tree Structure

A Merkle tree is a data structure used to prove the validity of a set of transactions, where each node represents a block in the chain. In Ethereum, a Merkle tree is built by hashing each transaction and combining them into a single block using the hashing function. Each node in the tree stores the hashed value of one or more transactions.

Algorithm for searching for a specific node

To check whether a specific transaction Transaction A' exists in the Merkle tree, we need to perform the following steps:

• Generate Hash for Transaction A: First, we generate a hash for each transaction in the set (egA,B,CandD). For this purpose, we will use the SHA-256 hash function.

const getMerkleNode = (transactions) => {
const hashValues ​​= Transactions.map((transaction) => crypto.createHash('sha256').update(transaction).digest());
const root = hashValues[0];
for (let i = 1; i < hashValues.length; i++) {
const child = crypto.createHash('sha256').update(hashValues[i]).digest();
root = crypto.subhash({ input: root, algorithm: 'SHA-256', length: 32 }).update(child).digest();
}
return root;
};
const getMerkleTree = (transactions) => {
const tree = [];
transaction.forEach((transaction) => {
let node = getMerkleNode([transaction]);
while (node.length > 0 && !tree.some((t) => t === transaction)) {
for (let i = 0; i < node.length; i++) {
if (node[i].length > 0) {
node.push(getMerkleNode(node.slice(i)));
}
}
}
tree.push(node);
});
return tree;
};
const transaction = ['A', 'B', 'C', 'D'];
const merkleTree = getMerkleTree(transactions);

Now that we have a Merkle tree, we can check if a particular transaction Transaction A’ exists by traversing the tree and comparing it to the original transactions. Here’s how it can be done:

const checkTransaction = (transactions, targetTransaction) => {
const node = getMerkleNode([targetTransaction]);
return node.length > 0 && node[0].length === targetTransaction;
};
// Usage example:
console.log(checkTransaction(transactions, 'A')); // true
console.log(checkTransaction(transactions, 'E')); // false

In conclusion

To implement the Ethereum Merkle tree part in JavaScript, you need to perform the following steps:

• Generate hashes: calculate hashes for all transactions using SHA-256.

• Build Tree

  : Create a Merkle tree by hashing the hash value of each transaction to recursively create new nodes.

After building a Merkle tree, you can check if a particular transaction exists by traversing the tree and comparing it to the original transactions. This solution provides an effective way to verify the validity of transactions in the Ethereum blockchain.

Additional Note: Please note that this is a simplified example and should not be used in production without proper security checks and testing. In a real application, you will have to consider additional factors such as node verification, transaction confirmation, and other security measures.