19. HASH CALCULATION

Hash code is calculated with the following formula:
From request post parameters, all parameters are taken (except hash) and appended to a string:
  1. Sort all parameters by keys in alphabetical order.
  2. Append them in key1=value1&key2=value2.
  3. Append secret key, e.g.: key1=value1&key2=value2SECRET.
  4. Calculate the hash by using MD5 and send it along with the request.