Signal/TextSecure passphrase for encryption of stored msgs or for encrypting calls?

[pstein]

When I go to Signal App (formerly TextSecure) then I can enter a passphrase there.

For what exactly is this passphrase?

Is it only to encrypt locally stored msgs or is it as well for encrypting a live call/conversation?

In other words: Can I perform an encrypted voice call WITHOUT having to set a passphrase?

Peter

 

[svim]

Signal's passphrase is to secure the app and notifications on your phone. As far as texting and voice calls keep in mind that the encryption applies only when your recipient is also using the Signal app (end-to-end encryption). Otherwise you're just using standard SMS and calls.

 

[pstein]

So again: When my recepient and me use both Signal but both have NO passphrase setup then texting and voice calls are encrypted anyway?

Correct?

 

[svim]

Yes, correct. Signal's end-t0-end encryption isn't tied to setting a passphrase, that's more about preventing anyone else from using the app on your phone. The encryption part comes into play when you first installed the Signal app on your phone and then registered your phone number as your default phone number. Then when you're calling someone else, who also has their number registered to their Signal app on their phone, that connection is encrypted.

I'm not absolutely sure about the following though. The encryption probably doesn't apply to what's stored on your phone however, that's more a matter of encrypting your user storage via Android itself. If you passphrase your Signal app it will complicate things for someone who stole your phone but if they're persistent enough they'll just use a file manager to access the file system of your phone and look at your data/files that way. (Which is why it's a good idea to encrypt your phone to begin with whenever applicable.)