Step to create the signature：

• 1 Pick and Sort
  • Get all the Request header information and request body
  • Exclude signature field and field with empty value
  • Sort all the field by name of the parameter using ASCII code ordering (ascending)
• 2 Combine
  • Using sorted parameter to form the new string using this formula <parameter name>=<parameter value>, and each parameter pair value are separated by & symbol
  • We will sign the combined string using SHA256WithRSA
• 3 Invoke Signature function
  • Use the SHA256WithRSA signature function with the private key to sign the combined string, length of RSA key is 1024.
  • Encode the signature output into base64 format and append the value into signature field at request header