Kudos to Jan Koum and Brian Acton to, even in the face of billions of dollars, keep their backs firmly straightened and ensure this will never happen.
It would be the sudden death of WhatsApp and a major inconvenience to its users.
But if you think about Facebook, many people think "Privacy violation!". (And many people just shrug and say "but I will use it anyway!")
WhatsApp has always been VERY careful with personal details, which has been confirmed by a joint investigation from Canadian and Dutch privacy watchdogs. (Source: https://www.priv.gc.ca/media/nr-c/2013/nr-c_130128_e.asp)
But... How is that going to be now that Facebook acquired it. Facebook, that is known for large scale privacy violations. (To which you consent...)
The first argument/fear I have heard was "Yeah but... Facebook will now read all the messages you ever sent and build a profile!!"
Well... Let me tell you: that's not possible. And even it it WOULD be possible, it would be very very illegal.
Those agreements, which are binding, state:
You provide certain Personally Identifiable Information, such as your mobile phone number, push notification name (if applicable), billing information (if applicable) and mobile device information to WhatsApp when choosing to participate in various uses of the WhatsApp Service, such as registering as a user, updating your status or requesting status for your contacts. In order to provide the WhatsApp Service, WhatsApp will periodically access your address book or contact list on your mobile phone to locate the mobile phone numbers of other WhatsApp users (“in-network” numbers), or otherwise categorize other mobile phone numbers as “out-network” numbers, which are stored as one-way irreversibly hashed values.
WhatsApp does not collect names, emails, addresses or other contact information from its users’ mobile address book or contact lists other than mobile phone numbers—the WhatsApp mobile application will associate whatever name the WhatsApp user has assigned to the mobile telephone number in his/her mobile address book or contact list — and this occurs dynamically on the mobile device itself and not on WhatsApp’s servers and is not transmitted to WhatsApp. This means that if you have your friend’s mobile phone number associated with the name “Shakespeare” in your mobile address book, that’s the name that will appear for that mobile phone number in your WhatsApp contact list. We do not collect location data, but users may voluntarily share their location with other users via the WhatsApp Service.
So whilst Facebook *COULD*, with a minor modification to WhatsApp and the ToS, link your WhatsApp user profile to a Facebook profile and start mining those personal details: they can never read your chat history.The contents of messages that have been delivered by the WhatsApp Service are not copied, kept or archived by WhatsApp in the normal course of business. The WhatsApp Service is meant to be a SMS replacement, using data service through a user’s phone (either via cell network or wifi). Users type their messages, which are sent via data service to our servers, and routed to the intended recipient (who must also be a WhatsApp user), if that recipient is online. If the recipient is not online, the undelivered message is held in WhatsApp’s server until it can be delivered. If the message is undelivered for thirty (30) days, the undelivered message is deleted from our servers. Once a message has been delivered, it no longer resides on our servers. The contents of any delivered messages are not kept or retained by WhatsApp — the only records of the content of any delivered messages reside directly on the sender’s and recipient’s mobile devices (and which may be deleted at the user’s option). Notwithstanding the above, WhatsApp may retain date and time stamp information associated with successfully delivered messages and the mobile phone numbers involved in the messages, as well as any other information which WhatsApp is legally compelled to collect. Files that are sent through the WhatsApp Service will reside on our servers after delivery for a short period of time, but are deleted and stripped of any identifiable information within a short period of time in accordance with our general retention policies.
The terms specifically state that this behavior is not conducted and on top of that: WhatsApp guarantees that your messages are NOT stored on the WhatsApp servers. (this would also cost copious amounts of storage, whilst WhatsApp is designed to operate as cheaply as possible With one server being able to serve millions of users and no data retention is taking place.)
Rest assured, even in the face of Facebook acquiring WhatsApp: your current message history can NOT be read by Facebook.
Whilst the ToS remains unchanged: this will not be possible at any time. If they do change the ToS... You will find out soon enough, but the changes will only apply to NEW messages being sent: it's impossible that it will apply to old messages, and those are not stored on the WhatsApp servers anyway.
Long story short: your data is safe!!
The only things that can change this are:
2.) Soon it will most likely be possible to link your WhatsApp to your facebook account: once you do that, Facebook WILL obtain access to your account and WILL be able to read your messages.
However, thanks to the hard work of Jan and Brian, it seems highly unlikely that you will be forced to ever link with Facebook: if that even will ever be possible to begin with.
These are legally binding agreements, so it's impossible that this is changed in a retroactive way. Facebook will NEVER be able to read your current messages nor your current history. That's all safe.
So should we fear this acquisition? I think not.
At least: there is currently absolutely no reason to fear for data you are currently sending (whilst the ToS is unchanged) and any data/messages you may have submitted in the past, considering WhatsApp does not store any messages.
Hope this blog helps to bring you a bit of peace.
Thanks for reading.