<?php
function generate_token()
{
  return base64_encode(openssl_encrypt(
    md5('$847968@') .
    '|'.
    md5(date('Y-m-d')),
    'AES-256-CBC', '6d57a9335c6838d9d7d096e0dec05e60a0e0d5f83bc2b25396c9a06371f52fdd', 0, '3254e58df7b2beec')
  );
}

$url = 'http://arenapoa.tecnologia.ws/webservice';

$username = base64_encode(openssl_encrypt('murilo.rocha@arenadunas.com.br', 'AES-256-CBC', '6d57a9335c6838d9d7d096e0dec05e60a0e0d5f83bc2b25396c9a06371f52fdd', 0, '3254e58df7b2beec'));
$password = base64_encode(openssl_encrypt('123456', 'AES-256-CBC', '6d57a9335c6838d9d7d096e0dec05e60a0e0d5f83bc2b25396c9a06371f52fdd', 0, '3254e58df7b2beec'));

$ch = curl_init();

$fields = array(
  'action' => urlencode('login_user'),
  'token' => generate_token(),
  'username' => $username,
  'password' => $password
);
$fields_string = '';
foreach($fields as $key=>$value) {
  $fields_string .= $key.'='.$value.'&';
}
rtrim($fields_string, '&');

curl_setopt($ch,CURLOPT_URL, $url);
curl_setopt($ch,CURLOPT_POST, count($fields));
curl_setopt($ch,CURLOPT_POSTFIELDS, $fields_string);

$result = curl_exec($ch);
curl_close($ch);