KeyRotationObjective.php

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<?php

declare(strict_types=1);

namespace ILIAS\FileDelivery\Setup;

use ILIAS\Setup\Artifact\BuildArtifactObjective;
use ILIAS\Setup;

class KeyRotationObjective extends BuildArtifactObjective
{
    public const KEY_ROTATION = './src/FileDelivery/artifacts/key_rotation.php';
    public const KEY_LENGTH = 32;
    private const NUMBER_OF_KEYS = 5;

    public function getArtifactPath(): string
    {
        return self::KEY_ROTATION;
    }

    public function build(): Setup\Artifact
    {
        $current_keys = null;
        if (is_readable(self::KEY_ROTATION)) {
            $current_keys = require self::KEY_ROTATION;
        }

        $new_keys = [];

        if (is_array($current_keys)) {
            // drop the first key
            $current_keys = array_slice($current_keys, 1);
            $new_keys = $current_keys;
        }
        // $push a new key to the array at first position
        while (count($new_keys) < self::NUMBER_OF_KEYS) {
            $new_keys[] = $this->generateRandomString(self::KEY_LENGTH);
        }
        // keep only the first 5 keys
        $new_keys = array_slice($new_keys, 0, self::NUMBER_OF_KEYS);

        return new Setup\Artifact\ArrayArtifact($new_keys);
    }

    private function generateRandomString(int $length): string
    {
        $return = '';
        for ($i = 0; $i < $length; $i++) {
            $return .= chr(random_int(33, 125));
        }
        return $return;
    }
}