The boss of WhatsApp says it will not “lower the security” of its messenger service.

If asked by the government to weaken encryption, it would be “very foolish” to accept, Will Cathcart told the BBC.

Government plans to detect child sex-abuse images include the possible scanning of private messages.

The NSPCC has criticised WhatsApp’s position, saying that direct messaging is “the front line” of child sexual abuse.

The government says tech firms need to tackle child-abuse material online.

Its proposals are part of the Online Safety Bill, which has been delayed until the autumn.

“They shouldn’t ignore the clear risk that end-to-end encryption could blind them to this content and hamper efforts to catch the perpetrators,” said
a government spokesperson.

“We continue to work with the tech sector to support the development of innovative technologies that protect public safety without compromising
on privacy.”

End-to-end
encryption (E2EE) provides the most robust level of security, because –
by design – only the intended recipient holds the key to decrypt the
message, which is essential for private communication.

The
technology underpins the online exchanges on apps including WhatsApp
and Signal and – optionally – on Facebook messenger and Telegram.

Only the sender and receiver can read those messages – not law enforcement or the technology giants.

The
conundrum currently facing the technology community is the UK
government’s pledge to support the development of tools which could
detect illegal pictures within or around an E2EE environment, while
respecting user privacy.

Experts have questioned whether it is possible to achieve – and most conclude client-side scanning is the only tangible option. But this destroys the
fundamentals of E2EE, as messages would no longer be private.