WhatsApp Server and Privacy - WhatsApp Security

When you install WhatsApp messenger, all your contacts will be uploaded to the WhatsApp server. It takes every contacts regardless of the fact whether the person in the address book is a Whatsapp user or not. This enables to quickly update the contacts list in the messenger.

This is a major WhatsApp security concern as in the case if the server is hacked, the hacker will get access to all the contacts stored in their server, even though this information is stored in encrypted format and will not store any other details associated with the phone number.

Privacy of Messages or Files Sent Through WhatsApp

WhatsApp does not copy nor store the messages sent through its messaging system. Even if the recipient is not connected to the internet and haven't received the message, the undelivered messages will be kept in WhatsApp servers and may be stored in those servers for up to 30 days. After this period of time, messages are deleted; and from that moment on messages will only be stored in the emitter’s and the recipient’s devices. But they may store the date and time of delivered messages, as well as the mobile phone numbers of the devices involved.

WhatsApp states that files that are sent using WhatsApp service are kept in their servers only for a short period of time. After this time they are finally eliminated according to their “general retention policies”.

Another major WhatsApp privacy concern is that a user does not need to send a friend request to send messages to another user, anyone having phone number could send message to any other person. However, users can block numbers on WhatsApp.