If you’re making a phone call with your iPhone, there used to be two options: Accept that any wiretapper, hacker can listen in on your conversations, or pay for pricey voice encryption software.
As of today the open source software group known as Open Whisper Systems has announced the release of Signal, this is the first iOS app designed to enable easy, strongly encrypted voice calls for free.
Open WhisperSystems plans to add secure text messaging to the iPhone app later this summer. And for Android users who already enjoy the RedPhone encrypted voice call app and TextSecure encrypted messaging app, the two will soon be merged into a single Signal app in order to consolidate the branding and whittle everything down to a single app.
Signal encrypts calls with a well-tested protocol known as ZRTP and AES 128 encryption, in theory strong enough to withstand all known practical attacks by anyone from script-kiddy hackers to the NSA.