Credit card encryption related

Hi,

We have a requirements where we have a external signup web page developed in PHP programming which calls Appian Web API for payment gateway process. Do we required encryption of credit card number and CVV code before sending request to Appian's web API. And when the request received, it further decrypt the credit card details for  further payment processing. 

If answer is "Yes" than what encryption and decrption methods best suits for this purpose in order to secure the payment process.

Thanks!

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