All stores include a free shared SSL certificate, a separate certificate is not needed. The shared SSL certificate is automatically activated for each store and no special setup is required.
This SSL certificate will protect your customers sensitive information using a 128 bit secure connection which is the highest level of security available commercially.
**The shared certificate is under the storesecured.com domain name and thus during checkout all shoppers will be taken to the stores unique storesecured.com URL, ie https://mystore.storesecured.com vs https://www.mystore.com. The store will look exactly the same during this transition and only the URL will change.