The NSA might be listening to your phone calls. Hackers may be listening to your phone calls. Not anymore.

On Tuesday the group Open Whisper Systems announced the release of Signal- the first iOS app that strongly encrypts voice calls for free.

“We’re trying to make private communications as available and accessible as any normal phone call,” says Moxie Marlinspike, the hacker security researcher who founded the nonprofit software group. Later this summer, he adds, encrypted text messaging will be integrated into Signal, too, to create what he describes as a “single, unified app for free, easy, open source, private voice and text messaging.”

Signal uses well-tested protocol known as ZRTP and AES 128 encryption to encrypt calls. Theoretically, their process should be strong enough to withstand all known practical attacks by anyone trying to listen to your calls.

Signal users can make free calls to other Signal users.

The way it works, in a practical sense, is a pair of words will appear on a screen to the receiver of the call. The receiver is then supposed to read aloud the two words to the caller as a form of authentication. If they match, the caller will be sure he or she is talking to the correct person, and that no one is eavesdropping in.

If you ever need to talk about private things and want piece of mind that no one is listening, give Signal a shot. Perhaps you’re a journalist talking to a source. Or you’re talking about bank or credit card info. I think there are a lot of uses for Signal, and I figured you’d like to know about it.

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