All payments in the establishments operating in foreing exchange in Cuba must be made with convertible pesos.
Convertible pesos will remain at par with the US dollar at an exchange rate of one for one.
You may exchange Euros, Canadian dollars pounds sterling or Swiss francs for convertible pesos. The exchange rates for those currencies are set in accord with the exchange rates on the international market.
You may also exchange US dollars for convertible pesos, but a service charge of 20 percent will be leived.
Travelers are advised to exchange money only at official exchange bureau's or banks to avoid scams confusing the two currencies. Never exchange money using street hustlers who will offer you a great deal. These are almost without exception scams - there's no deal to be had and you run a big risk of having your money stolen.