PHPTree is now having a Merkle node type.

merkle.php

<?php

declare(strict_types=1);

use drupol\launcher\Launcher;
use drupol\phptree\Exporter\Image;
use drupol\phpmerkle\Hasher\DummyHasher;
use drupol\phptree\Node\MerkleNode;

include './vendor/autoload.php';

// Default node capacity.
// This is the maximum number of children that a node can have.
// A Merkle node is a binary tree, so by default it uses 2.
// Using another value is fully possible.
$capacity = 2;

// By default, a Merkle tree uses a double SHA256 encoding.
// For this demo, I'm using a dummy hasher that returns the $value without hashing it.
$hasher = new DummyHasher();

// Create the root node.
$tree = new MerkleNode('root', $capacity, $hasher);

// Prepare the data to use.
$sentence = 'Science is made up of so many things that appear obvious after they are explained .';
$input = array_merge(array_pad([], 14, null), explode(' ', $sentence));

// Add the nodes to the tree.
foreach ($input as $v) {
    $tree[] = new MerkleNode($v, $capacity, $hasher);
}

// Export the tree to an image.
$imagePath = (new Image())->setFormat('png')->export($tree);

// To open the image directly, you can use an optional package: drupol/launcher
// do: composer require drupol/launcher
// Then you'll be able to use the Launcher.
Launcher::open($imagePath);

This script produces this image (using a DummyHasher):

Using a DoubleSha256 hasher:

Now using a randomized tree with fake ids as values.

And the normalization of the tree, needed to computer the hashes:

We can even change the maximum amount of children that a node can have. This is no more a binary tree (2 children only). Each node can have maximum 3 children.

After normalization:

Another example with maximum 4 children:

After normalization: