Martin Blatter is not impressed by WhatsApp. The head of the Swiss messenger service Threema advises caution with providers who make their services available free of charge. Because then business will be done with the users' data. At the same time, Blatter warns against a weakening of the encryption in the name of the fight against terrorism. WORLD: Mr. Blatter, most people don't use Threema, but WhatsApp. They also? Martin Blatter: No. WORLD: Why not? WhatsApp encrypts end-to-end just like Threema.