We are using Paypal for charging users. Right now, we have API call to BillUser to charge the user without authorization. We would like to change this to authorize first and charge at later point of time. Also, we would not like to redirect the user to Paypal page and we have Billing Agreement id for each of the accepted user. I was looking into Paypal APIs and found DoAuthorization() method which would help our need. But, this takes a transaction id as the input. How do i get this transaction id?
I can update the API to latest one using Nuget install-package PaypalMerchantSdk and use DoReferenceTransaction() method to authorize/capture payment. But, the problem with this is that it mandates API signature. We have API certificate for sandbox and live environment. We do not want to use API signature. Is there a C# example of using API certificate and calling this method without signature?