Restored from the project wiki (we.riseup.net), which is no longer online.
TextSecure is an app developed by Moxie Marlinspike of the Open Whisper Systems project, and is available free of charge on the Android Market. It is free and Open Source software.
TextSecure encrypts both the SMS messages sent over the air and those stored on the phone. It is designed to replace the default Android application for managing SMS, and it is just as simple to use.
Using TextSecure, all messages (sent and received) are encrypted locally, so if the phone is seized, lost or stolen, your messages will be safe. And this works even if the recipient of your SMS does not use TextSecure.
Encrypting the messages that travel over the air, on the other hand, requires a few extra steps:
On startup, the application asks for your encryption passphrase:
You can choose the recipient of your SMS from the address book:
The first time you write to a contact you will need to verify the session, so that you can be sure you are encrypting the SMS with the right person’s key. Unfortunately this procedure has to be done in person.
Click on “Verify Session”
A code will appear on both phones; if everything matches then the verification succeeded and you can send SMS securely.
