, __( 'Invalid cookie format.' ) );
		}

		return $parts;
	}

	/**
	 * Generates the recovery mode cookie value.
	 *
	 * The cookie is a base64 encoded string with the following format:
	 *
	 * recovery_mode|iat|rand|signature
	 *
	 * Where "recovery_mode" is a constant string,
	 * iat is the time the cookie was generated at,
	 * rand is a randomly generated password that is also used as a session identifier
	 * and signature is an hmac of the preceding 3 parts.
	 *
	 * @since 5.2.0
	 *
	 * @return string Generated cookie content.
	 */
	private function generate_cookie() {
		$to_sign = sprintf( 'recovery_mode|%s|%s', time(), wp_generate_password( 20, false ) );
		$signed  = $this->recovery_mode_hash( $to_sign );

		return base64_encode( sprintf( '%s|%s', $to_sign, $signed ) );
	}

	/**
	 * Gets a form of `wp_hash()` specific to Recovery Mode.
	 *
	 * We cannot use `wp_hash()` because it is defined in `pluggable.php` which is not loaded until after plugins are loaded,
	 * which is too late to verify the recovery mode cookie.
	 *
	 * This tries to use the `AUTH` salts first, but if they aren't valid specific salts will be generated and stored.
	 *
	 * @since 5.2.0
	 *
	 * @param string $data Data to hash.
	 * @return string|false The hashed $data, or false on failure.
	 */
	private function recovery_mode_hash( $data ) {
		if ( ! defined( 'AUTH_KEY' ) || AUTH_KEY === 'put your unique phrase here' ) {
			$auth_key = get_site_option( 'recovery_mode_auth_key' );

			if ( ! $auth_key ) {
				if ( ! function_exists( 'wp_generate_password' ) ) {
					require_once ABSPATH . WPINC . '/pluggable.php';
				}

				$auth_key = wp_generate_password( 64, true, true );
				update_site_option( 'recovery_mode_auth_key', $auth_key );
			}
		} else {
			$auth_key = AUTH_KEY;
		}

		if ( ! defined( 'AUTH_SALT' ) || AUTH_SALT === 'put your unique phrase here' || AUTH_SALT === $auth_key ) {
			$auth_salt = get_site_option( 'recovery_mode_auth_salt' );

			if ( ! $auth_salt ) {
				if ( ! function_exists( 'wp_generate_password' ) ) {
					require_once ABSPATH . WPINC . '/pluggable.php';
				}

				$auth_salt = wp_generate_password( 64, true, true );
				update_site_option( 'recovery_mode_auth_salt', $auth_salt );
			}
		} else {
			$auth_salt = AUTH_SALT;
		}

		$secret = $auth_key . $auth_salt;

		return hash_hmac( 'sha1', $data, $secret );
	}
}