REST API Implementation with URL Params


I have an API hosted on our cloud and I want to users to call my API through Tyk API Gateway. My API needs 2 URL params to be called which is param1 and param2. param2 is the signature and I have configured public key on the certificates section of tyk cloud.

My users will send just param1 and I want tyk to send param1 as is to my API and param2 with encrypted signature (which is encrypt of whatever I am sending to param1) to my API.

Can you all please advise how can I use and achieve it? I am using tyk cloud>