Generate unique hex string in PHP

unique_hex_string.php

<?php
function generate_unique_hex_string($length) {
    // Calculate the number of bytes needed for the desired length of the hexadecimal string
    $byte_length = ceil($length / 2);

    // Generate random bytes
    $random_bytes = random_bytes($byte_length);

    // Convert the random bytes to a hexadecimal string
    $hex_string = bin2hex($random_bytes);

    // Get the current timestamp (UNIX timestamp)
    $timestamp = time();

    // Append the timestamp to the hexadecimal string
    $hex_string .= dechex($timestamp);

    // Truncate the string to the desired length (if necessary)
    $hex_string = substr($hex_string, 0, $length);

    return $hex_string;
}

// Example usage:
$unique_hex_string = generate_unique_hex_string(13); // Generates a 16-character hexadecimal string with a timestamp
echo $unique_hex_string;