A known issue respect to WhatsApp privacy, is the fact that WhatsApp requires its users send all their contacts to the application server, so you can connect with others just only using the contacts application.
While this method is very fast and useful, knowing that its contact is established application sharing, while providing a copy of our data replicated on the servers of the company, including those who do not make use of it is not a subject to leave the planet without firing a heated argument.
In theory, the operation makes the information on the phone numbers are stored using hash and not providing other information that can identify you, such as name and surname.
The March 31, 2013, the Telecommunications Authority in Saudi Arabia, Communications and Information Technology Commission (CITC), has issued a statement regarding the possible restrictive measures against WhatsApp, and other applications like Skype and Viber, invitation providers of these services to adapt to the rules of his country, in relation to monitoring and privacy.
Via Whatsapp privacy against other users
Via Whatsapp Privacy against Whatsapp
Why there's no privacy
Ever since the emergence of Facebook, the world found reason to look out tests users do not enjoy maximum security against eavesdropping. Whatsapp is owned by the same company. There is no service to take this and put it in another hierarchy of respect that choose to use reason. It is a logical condition: he wants to use it for free or cheapie, banque that they observe.