Privacy protection of chat apps is questioned following terror attack
Home Secretary says encrypted messages should be accessible to investigators
Following last week’s terror attack in London, the privacy protections of chat apps have come under fierce scrutiny.
Home Secretary Amber Rudd has said that intelligence services must be able to access relevant information from chat apps which promise to prevent messages being accessed by strangers.
Her comments come following the discovery that Khalid Masood appeared to have used WhatsApp minutes before carrying out his killings in Westminster.
Although it is not yet known whether that action was related to the atrocity, the Home Secretary has summoned WhatsApp's owner, Facebook, and other technology companies to a meeting to discuss ways to ensure that security officers get the data they need in the future.
Several chat apps have adopted a technique called end-to-end encryption. This digitally scrambles their messages' contents when it leaves a sender's device, and then reassembles it on the recipient's computer using a shared key.
The technology company running the service is not made privy to the key, so is unable to make sense of the conversation even though it passes through its computer servers.
Some apps, including WhatsApp, Apple's iMessage, Signal and Threema, use end-to-end encryption by default. Others, such as Telegram, Line and Google's Allo, offer it as an option.
If end-to-end encryption is active, the technology company running the app is limited in what useful information it can remotely disclose.
But if a phone, tablet or PC is not passcode-protected - or if the authorities find a way to bypass the code - the physical device itself will provide access.