(Whisper Systems also offers an encrypted mobile voice app, RedPhone).
Last November, Twitter acquired Whisper Systems, a security service for mobile devices.
They include Signal (from the Open Whisper Systems not-for-profit organisation) and Threema.
The encryption itself is being provided by Open Whisper Systems via open source messaging app Text Sure.
Shortly after the Guardian published its story, Open Whisper Systems tweeted to clarify that it has no relationship to Whisper.
As its maker, Whisper Systems, observed on its blog: "A user simply sends a message, and it's encrypted end to end, every time.
In a blog post, the Open Whisper Systems team said the WhatsApp project "represents the largest deployment of end-to-end encrypted communication in history".
It's working with the company behind TextSecure, Open Whisper Systems, which described the partnership as "the largest deployment of end-to-end encrypted communication in history".
Though it has just created a rival, Open Whisper Systems will continues to work on its own products, which include RedPhone for Android for encrypted voice communications and the iOS Signal apps that do protected calls and messaging.
Moxie, who is also a contributor to Open Whisper Systems, a secure communications project which has no relation to Whisper (but has long held a grudge against the start-up for appropriating its name), was writing in response to Whisper's chief technical officer, Chad DePue, on the link sharing site Hacker News.
In fact, it's possible to fit the basic guidelines in a tweet, like this from the pseudonymous security researcher the grugq: Encrypted messaging has got a lot easier over the past few years, particularly with the rise of encrypted texting apps such as Signal, developed by Open Whisper Systems.
