The loss of industrial secrets is perhaps even more worrying to companies than that of their customers' credit-card data.

ECONOMIST: Businesses and cyber-security

Polo Ralph Lauren said it was informed last autumn that some of its customers' credit card information "may have been misappropriated" but did not detail any specific incidents.

BBC: Identity theft is taking some of the shine off credit cards

He points out that when a private corporation is in control of a currency, there has to be trust in its ability to look after its customers' credit.

BBC: Digital currency: Brave new world or criminal haven?