Using Redis to implement Merkle Tree in PHP

With the rapid development of the Internet, data exchange and sharing have become more and more convenient, but it has also brought about issues of data security and privacy. Merkle Tree is a hash tree structure that can effectively ensure the integrity and consistency of data. Redis is a high-performance in-memory database. Using it to implement Merkle Tree can improve the reading and writing speed and availability of data. This article will introduce how to implement Merkle Tree using PHP and Redis.

1. What is Merkle Tree

Merkle Tree is a hash tree structure, a data structure used to verify the integrity and consistency of large data collections . A Merkle Tree consists of a set of data blocks, each of which has a unique hash value. Each non-leaf node of a Merkle Tree is the hash value of the hash value of its child node. Ultimately, the root node becomes the only point of reference for verifying the integrity of the entire data structure. If a data block in the Merkle Tree is changed, the hash value of its parent node and above nodes will be affected.

2. Why use Merkle Tree

The most common application scenario of Merkle Tree is to verify the integrity and consistency of the ledger in blockchain technologies such as Bitcoin and Ethereum. sex. Since distributed ledgers require a huge amount of data to be verified, using Merkle Tree can greatly improve verification efficiency and speed. At the same time, Merkle Tree is also suitable for other scenarios where data integrity and consistency need to be verified, such as file transfer, data backup, etc.

3. Introduction to Redis

Redis is a high-performance Key-Value in-memory database with features such as fast read and write speed, data persistence function, and support for complex data types. . Redis is often used in cache systems, publish and subscribe systems, rankings and other scenarios.

4. How to use Redis to implement Merkle Tree

The key to using Redis to implement Merkle Tree is how to store the structure of Merkle Tree into Redis. The following is a possible implementation method:

• Define the node structure of Merkle Tree

class Node {
    public $left = null;
    public $right = null;
    public $data = null;
    public $hash = null;
}

• Recursively build Merkle Tree

function makeTree($data) {
    if(count($data) == 1) {
        $node           = new Node();
        $node->data     = $data[0];
        $node->hash     = hash('sha256', $node->data, false);
        return $node;
    }

    $leftData       = array_slice($data, 0, count($data) >> 1);
    $rightData      = array_slice($data, count($data) >> 1);
    $left           = makeTree($leftData);
    $right          = makeTree($rightData);

    $node           = new Node();
    $node->left     = $left;
    $node->right    = $right;

    if(!is_null($node->left)) {
        $node->hash = hash('sha256', $node->left->hash . $node->right->hash, false);
    }

    return $node;
}

• Storing Merkle Tree to Redis

function storeToRedis($node, $redis, $key) {
    if(is_null($node)) {
        return;
    }

    $redis->hset($key, 'hash', $node->hash);
    $redis->hset($key, 'data', $node->data);

    if(!is_null($node->left)) {
        $leftKey    = $key . ':left';
        $rightKey   = $key . ':right';

        storeToRedis($node->left, $redis, $leftKey);
        storeToRedis($node->right, $redis, $rightKey);

        $redis->hset($key, 'left', $leftKey);
        $redis->hset($key, 'right', $rightKey);
    }
}

• Reading Merkle Tree from Redis

function loadFromRedis($redis, $key) {
    if(!$redis->hexists($key, 'hash')) {
        return null;
    }

    $node           = new Node();
    $node->hash     = $redis->hget($key, 'hash');
    $node->data     = $redis->hget($key, 'data');

    $leftKey        = $redis->hget($key, 'left');
    $rightKey       = $redis->hget($key, 'right');

    if(!is_null($leftKey)) {
        $node->left     = loadFromRedis($redis, $leftKey);
        $node->right    = loadFromRedis($redis, $rightKey);
    }

    return $node;
}

• Verify data integrity

function verifyData($data, $rootHash, $redis, $key) {
    $node   = loadFromRedis($redis, $key);

    if(is_null($node)) {
        return;
    }

    if(!is_null($node->left)) {
        verifyData($data, $rootHash, $redis, $redis->hget($key, 'left'));
        verifyData($data, $rootHash, $redis, $redis->hget($key, 'right'));
    }

    if(!is_null($node->data)) {
        $dataHash = hash('sha256', $node->data, false);
        $index    = array_search($node->data, $data, true);

        if($node->hash != $rootHash || ($index === false && $node->hash != $dataHash)) {
            throw new Exception('Invalid data or hash');
        }
    }
}

5. Summary

This article introduces how to use PHP and Redis to implement Merkle Tree, which is very suitable for scenarios with high read and write speeds and large amounts of data. In addition, it can be combined with other technologies, such as encryption algorithms and signature verification, to improve data security and privacy protection.

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