WordPress: wp_create_nonce() not creating a value inside custom plugin - wordpress

Question

I am creating a custom plugin for user registration with the following steps:
A function to create my HTML form fields
function render_registration_form() {
ob_start();
...
<input type="hidden" id="register_nonce" name="register_nonce" value="<?php wp_create_nonce('generate-nonce'); ?>" />
//Above line does not create a nonce at all
...
return ob_get_clean();
}
A function to use as shortcode to display the above form
function custom_user_registration_form() {
//Render registration form only if user is not logged in already!
if(!is_user_logged_in()) {
$registration_enabled = get_option('users_can_register');
if($registration_enabled) {
$output = render_registration_form(); (written above)
} else {
$output = __('User registration is not enabled');
}
return $output;
} else {
return _e('You are already logged in!');
}
}
add_shortcode('register-user', 'custom_user_registration_form');
A function to validate and add a new user along with meta to the database:
function validate_and_create_user() {
if(isset($_POST['txt_username']) && wp_verify_nonce($_POST['register_nonce'], 'register-nonce')) {
$user_data = array(
'user_login' => $loginid,
'user_pass' => $password,
'user_nicename' => $first_name,
'display_name' => $first_name . ' ' . $last_name,
'user_email' => $email,
'first_name' => $first_name,
'last_name' => $last_name,
'user_registered' => date('Y-m-d H:i:s'),
'role' => 'subscriber'
);
$new_user_id = wp_insert_user($user_data);
...
}
add_action('init', 'validate_and_create_user');
Since no nonce value is getting created inside the form the check wp_verify_nonce($_POST['register_nonce'], 'register-nonce') always fails and no user data is getting saved in the database.
According to https://codex.wordpress.org/Pluggable_Functions
Pluggable functions are no longer being added to WordPress core. All new functions instead use filters on their output to allow for similar overriding of their functionality.
I am new to WordPress. Don't have any idea about how to solve this! Any help would greatly help me.

Answer 1

Try This:
wp_nonce_field('register_nonce');
in the place of input.
And for retrieving nonce use following
$retrieved_nonce = $_REQUEST['_wpnonce'];
if (!wp_verify_nonce($retrieved_nonce, 'register_nonce')) die( 'Failed security check' );