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The popular service WhatsApp has upped the ante on encryption, expanding protections so that only the sender of a message and its recipient will be able to see what's said.

The app, which has more than one billion users around the world, first started to introduce encryption into its product a year and a half ago. Now, messages sent over the company's app will be encrypted from the point they're sent until they're received, meaning that even WhatsApp will get only a garbled mess if it tried to listen in on a conversation.

“WhatsApp’s end-to-end encryption ensures only you and the person you’re communicating with can read what is sent, and nobody in between, not even WhatsApp,” the company said on its website on Tuesday. The change applies to all calls and messages made through the app after March 31.

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“All of this happens automatically: no need to turn on settings or set up special secret chats to secure your messages,” the company said.

The expansion of "end-to-end" encryption comes after a heated legal dispute between Apple and the FBI in California brought encryption and tech security into the spotlight. Law enforcement officials including FBI Director James Comey have repeatedly expressed fears in recent years that criminals and terrorists will use encrypted apps and messaging services to “go dark” and hide from the government.

WhatsApp has finished integrating the Signal Protocol into their app. End to end encryption for everyone by default: https://t.co/7IyZWWzW48 — Moxie Marlinspike (@moxie) April 5, 2016

WhatsApp's end-to-end encryption presents a "significant problem," FBI general counsel James Baker said during an appearance at the Global Privacy Summit on Tuesday.

"But the reality is that business decisions have consequences, so we have to figure out how to deal with that," Baker said.

Facebook and WhatsApp were among the companies that submitted amicus briefs last month supporting Apple in its case involving an iPhone used by San Bernardino terrorist Syed Farook.

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"Recently there has been a lot of discussion about encrypted services and the work of law enforcement,” WhatsApp said in a blog post on Tuesday. “While we recognize the important work of law enforcement in keeping people safe, efforts to weaken encryption risk exposing people's information to abuse from cybercriminals, hackers, and rogue states.”

Facebook acquired WhatsApp for $19 billion in 2014. Whatsapp founder Jan Koum, who was born in Ukraine, has been an outspoken proponent for strong encryption and security protections.

"We're glad to do our part in keeping people's information out of the hands of hackers and cyber-criminals," Koum wrote in a Facebook post.