http://www.paymentsgateway.com/developerDocumentation/Integration/securewebpay/redirect.aspx
Authentication
Authentication is done using a HMAC-MD5 hash that includes the following fields.
· pg_api_login_id (found in the Virtual Terminal)
· pg_transaction_type or pg_valid_transaction_type (can be blank)
· pg_version_number
· pg_total_amount or pg_valid_amount (can be blank)
· pg_utc_time
· pg_transaction_order_number (can be blank)
· pg_client_id (can be blank)
· pg_payment_method_id (can be blank)
· pg_client_command (can be blank)
· pg_payment_command (can be blank)
The API Login ID and Secure Transaction Key can be found in the Virtual Terminal under Gateway Settings.
Hash Examples
Standard Hash
pg_ts_hash = HMACMD5( pg_api_login_id + "|" + pg_transaction_type + "|" + pg_version_number + "|" + pg_total_amount + "|" + pg_utc_time + "|" + pg_transaction_order_number + "|" + pg_client_id + "|" + pg_client_command + "|" + pg_payment_method_id + "|" + pg_payment_command, pg_secure_transaction_key)