You’ll need to enable the Secure Socket Layer (SSL) on the page that submits the credit card information to the server. To do so you or your client will need to purchase a secure certificate for that domain. http://www.thawte.com is the most widely used. The client’s web host will probably have to apply on the client’s behalf then install the certificate. The bottom line: It’s the SSL, not a PHP scripting command, that encrypts the data passed from the browser back to the server.