Apple has hired Frederic Jacobs, one of the key developers who helped deliver Edward Snowden's preferred encrypted chat app to the iPhone and Android.
Jacobs, a Belgian-born privacy advocate and coder with a background in cryptography, will be joining Apple as an intern this summer and working within Apple's CoreOS security team. Jacobs announced the move on Twitter on Thursday.
Core OS is a layer in OS X and iOS. In iOS, it is used to manage app security when an iPhone connects to external hardware.
While it is only an internship,Jacobs joins Apple at a time when the company is facing intense pressure from US lawmakers and law enforcement over iPhone encryption. As such, Apple is paying extra attention to how encryption can tighten iPhone security.
Apple is in a heated battle with the government over a court order demanding it create a special version of iOS to help the FBI bypass iPhone password security features.
The order exploits a support feature that enables Apple to install an update to an iPhone without requiring users to entering their passcode. However, the New York Times reported this week that Apple has been working on a way to close the hole, which would make it technically possible to comply with a future order.
Signal, by Open Whisper Systems (OWS), is widely regarded as one of the most thoroughly-secured messaging apps and scores top marks in the Electronic Frontier Foundation's rating system, both for the security of its design and its openness to independent review.
OWS' apps TextSecure and RedPhone were available on Android for several before arriving on the iPhone as Signal.
Jacobs was instrumental in delivering the same cryptographically-secured messaging to the iPhone, which arrived as Signal 2.0 for iOS in March.
In November last year, Signal also arrived on Android, making it easier for secure messaging between users on different platforms. Edward Snowden noted at the time that he used the app every day.
Computer forensics expert Jonathan Ździarski recently gave Signal on iPhone the thumbs-up after extracting "virtually nothing" using backup and forensics tools.
Jacobs told Technologist last year that Signal offered one key advantage over iMessage, which already supported end-to-end encryption.
"Apple's service is not perfect," he said. "For example, its proprietary technology makes it impossible for the community to detect vulnerabilities and fix flaws."