Apple has rehired the cryptography expert behind the secure communications platforms Silent Circle, PGP Corp and Blackphone to boost the security features on its devices, Reuters reported Tuesday.

Jon Callas, who worked at Apple in the 1990s and again between 2009 and 2011, rejoined the tech giant in May, a spokesperson said.

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The company declined to elaborate on Callas’ role, but the move fits with repeated company assertions that it will continue to strengthen the security protections on its devices.

Apple’s robust encryption algorithms have been at the heart of the high-profile dispute between the law enforcement community and Silicon Valley over the degree of access that authorities should have into secure communications.

Apple earlier this year refused to help the FBI unlock the iPhone of one of the San Bernardino shooters, kicking off a bitter feud that was resolved only when the agency purchased a third-party tool to hack into the device.

Security experts and privacy advocates insist that to provide any guaranteed access for law enforcement is tantamount to a “back door” that will undermine the safety and privacy of everyday users of Apple’s devices.

Strong encryption, technologists say, is necessary to stay a step ahead of the onslaught of digital attacks from hackers consumers face everyday.

But authorities argue they have struggled to execute search warrants as end-to-end encryption — which allows only the sender and the recipient to read a message — becomes more readily available in the consumer market.

While the fight over the San Bernardino shooter's phone was shelved, the larger debate continues apace on Capitol Hill, where several bills attempting to resolve the tension are circulating both chambers.

One, from Sens. Richard Burr Richard Mauze BurrRep. Mark Walker says he's been contacted about Liberty University vacancy Overnight Defense: Trump rejects major cut to military health care | Senate report says Trump campaign's Russia contacts posed 'grave' threat Senate report describes closer ties between 2016 Trump campaign, Russia MORE (R-N.C.) and Dianne Feinstein Dianne Emiel FeinsteinMcConnell says Trump nominee to replace Ginsburg will get Senate vote Top Democrats call for DOJ watchdog to probe Barr over possible 2020 election influence Intensifying natural disasters do little to move needle on climate efforts MORE (D-Calif.), would require providers to provide "technical assistance" to investigators seeking access to locked devices.

Throughout the dispute with the FBI, Apple said repeatedly that it will continue to bolster the digital defenses of its products, even in the face of pushback from the Department of Justice.

“We will continue to increase the security of our products as the threats and attacks on our data become more frequent and more sophisticated,” Apple said in March.