![private contact discovery whatsapp private contact discovery whatsapp](https://eandvhk.imanagesystems.com/hornet/src?p=/ap6_001/hornet/prp/img/07eaa20a1f154e54870adbc922c08183-wtm.jpg)
Obviously this can protect your messages in case of theft however you probably won't gain that much security because most people will probably not choose good passwords here for usability reasons.
#Private contact discovery whatsapp password
Signal offers to encrypt the past communication at app level requiring a password to read past messages, which WhatsApp lacks completely. Though given they know the group membership to distribute messages, they may just store this in the clear. I was unable to find documentation on how WhatsApp handles this data. See this blog post for details and this post for the deployment announcement and this post for how group links factor into this. Private Group Metadataīecause the previously mentioned approach of everyone just directly sending the group messages to each other is messy with regards to privileges - as achieving consensus in an asynchronous distributed system is hard - Signal has deployed a new system to enforce access control and privileges in groups without learning anything about the group structure - only about the existence of a group and a guesstimate of its size based on the size of the server-stored ciphertext. The server-side fan-out is stated in the white paper (PDF). However they can still see that three messages are going to three different people at once and can guess that this is due to a group chat. So this way OpenWhisperSystems (the makers of Signal) doesn't learn your social group structures. In Signal on the other hand, group chats are actually normal peer-to-peer chats 1 with a special flag, which is set inside the end-to-end encrypted frame.
![private contact discovery whatsapp private contact discovery whatsapp](https://i.ytimg.com/vi/Npkl2CJOe0I/maxresdefault.jpg)
This way WhatsApp learns all the social structures and can in theory perform traffic analysis to deduce quite a bit of information from the message volume exchanged. When you use a group chat in WhatsApp, you send your message to the server who in turn distributes it to all the group members. There are still a couple of security functions, which may matter to you, which Signal does better than WhatsApp.