An analogue of a handwritten signature. How can it be implemented in php?

Question

PHP

Hello!
In my TOR for the development of the site, the implementation of the ASP is indicated.
By analogy with the site https://www.zaymer.ru/pages/viewPdf/signature_anal... (ASP has already been implemented on this site)
How can it be implemented?
As I understand it, a Simple Electronic Signature with confirmation via SMS is enough for this.
Will the following algorithm be considered PEP:

Inside shitcode

<?php

function getHMACsms(){

  $key = 'тут закрытый ключ';

  $return = array();

  date_default_timezone_set('UTC');

  $timestamp = calc_timestamp();

  $code = rand(1000,9999);

  $phone = str_replace(array('(',')','-','+'),array('','','',''), $_POST['calc-phone']);

  $mac_data = tomacdata($_POST['calc-surname']).
              tomacdata($_POST['calc-name']).
              tomacdata($_POST['calc-lastname']).
              tomacdata($phone).
              tomacdata($timestamp).
              tomacdata($code);

  $return['HMAC'] = hash_hmac("sha1",$mac_data,hex2bin($key));
  $return['TIMESTAMP'] = $timestamp;

  $ch = curl_init("https://sms.ru/sms/send");
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); 
  curl_setopt($ch, CURLOPT_TIMEOUT, 30);
  curl_setopt($ch, CURLOPT_POSTFIELDS, array(

    "api_id"    =>  "тут ключ апи sms.ru",
    "to"      =>   $phone,
    "text"    =>  "Код согласия с условиями и обязательствами " . $code . ". сайт.рф"

  ));
  $body = curl_exec($ch);
  $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
  curl_close($ch);

  $json["body"] = $body;

  if($httpcode == 200 && $body == 100){
    return $return;
  }else{
    return false;
  }
}


function tomacdata($oFld)
{
  $str="";

  if ($oFld == "") {
   $str = "-";
  } else {
   $str = strlen($oFld).$oFld;
  }
  return $str;
}

function calc_timestamp()  {
    return date("YmdHis");
}

And what legal force will this algorithm have in court?
Upd: So, from a legal point of view, I understood everything. Now we are interested in whether the above algorithm is a PEP?