How WhatsApp encryption works - and why there shouldn't be a backdoor

A battle between national security and privacy is brewing. Governments and secret services are asking encrypted messaging services such as WhatsApp to allow them access to users’ data. Most recently, in the wake of the March attack at Westminster, Amber Rudd, the UK home secretary, said it was unacceptable that the government couldn’t read the encrypted messages of suspected terrorists.

The main argument behind this request is that access to messages will allow authorities to thwart future terror attacks. On the other hand, there are many ordinary people who use messaging apps for daily communication and this request would be a direct breach of their privacy.But this isn’t the only problem – creating a way for the authorities to read encrypted messages would also make the system vulnerable to cyber attacks from criminals and other hackers, removing what makes it a secure way to communicate in the first place.

How does encryption work?

Encryption is simply a way for two or more users to exchange messages securely. Encryption algorithms are like a box with two locks. For example, if a user called Alice wants to send her friend Bob a secure message, she puts it in the box and locks it with her key. Then, she sends the locked box to her friend Bob, who can only open the box and read Alice’s message if he has a valid key of his own.

But to be able to communicate with new users, you need a way of sharing keys that is still secure. To get over this, each user has what’s called a public key that is available to anyone and proves the identity of the user, and a private key that stays with the user. Alice uses Bob’s public key to lock the box, but it can only be unlocked with Bob’s private key. Read More