Calls for security agencies to have access to messaging apps such as WhatsApp were raised again after the Westminster attack

Calls for security agencies to have access to messaging apps such as WhatsApp were raised again after the Westminster attack.

Here are the questions surrounding the apps:

1. What is encryption?

Encryption means sending information in a way that only authorised people can access it. In practice, this means the original message is scrambled using an algorithm.

This creates a new message, or cyphertext, which should look like nonsense to anyone spying in.

Only people with the correct decryption keys can unlock the message back into its original meaning.

There are different ways to encrypt messages, and many different services, but it is fundamentally based on mathematics.

2. How does it work?

Most end-to-end encrypted services rely on a public/private key encryption.

Each person has two keys. The private key is yours alone, and used to decrypt messages that are sent to you.

For services like iMessage and WhatsApp, this is kept on your device and done automatically.

Your public key is available to anyone – it is used to encrypt messages in a way that can only be decrypted by you, with your private key. The public key is a bit like a personal delivery locker. Anyone can put a package in for you, but only you can unlock it.

3. Which services are encrypted?

Pretty much the entire digital world runs on encryption. Any message can be encrypted – and the way the internet works is by swapping messages.

Encryption keeps your bank details safe when you shop online or in the real world, when you take money out of a cash machine.
Every time you make a mobile phone call, it’s (to some extent) encrypted.

The current row focuses on messaging apps, though. Services like WhatsApp and iMessage serve more than a billion users and offer encryption.

Then there is a host of other, lesser known apps, including Signal and Telegram, that offer secure private messaging.

4. Can the company (ie WhatsApp, Apple) see encrypted messages on their platforms?

End-to-end encryption should mean only you and the person you are speaking with can see the message – so Apple and WhatsApp will not see it.

However, if you are backing up your messages to the Cloud – an option in settings – they keep this data unencrypted, and could hand it over to governments if legally obliged.