How to create a secure credit card gateway using paypal / ruby on rails / active merchant

Question

I am creating a store using Active Merchant and PayPal sandbox right now. It seems to be working fine, but I don't think it is even remotely secure. I don't really know too much about HTTPS and how to implement secure connections.

I am currently passing the credit card and billing information in the session (probably not the smartest idea). My current code is posted below. I really need help with what direction and steps to take in order to make this a secure, usable store.

 def payment
session[:billing_address] = params[:billing_address] 
 end

 def summary
    @credit_card = params[:credit_card]
    session[:credit_card] = params[:credit_card]
    @billing_address = session[:billing_address]
    @cart = get_cart
    @purchases  = @cart.purchases
    @total = @cart.total
 end

 def finish
     @cart = get_cart
     @total = @cart.total

     credit_card = ActiveMerchant::Billing::CreditCard.new( session[:credit_card] )

     billing_address = session[:billing_address]

     flash[:notice] = credit_card.errors and return unless credit_card.valid?

     gateway = ActiveMerchant::Billing::PaypalGateway.new(:login=>$PAYPAL_LOGIN, :password=>$PAYPAL_PASSWORD)

     res = gateway.authorize(@total, credit_card, :ip=>request.remote_ip, :billing_address=>billing_address)

     if res.success?
        gateway.capture(@total, res.authorization)
        flash[:notice] = "Authorized" 
     else
        flash[:notice] = "Failure: " + res.message.to_s
     end    
  end

Answer 1

There was a good railscast about how to implement ssl.

http://railscasts.com/episodes/143-paypal-security