There's a physical necessity to keep all of the information necessary to decrypt messages in the app's folder.
Anything the signal app shows you can also be seen by an app with access to Signal's data on that device. This is true of any E2E encrypted messenger service.
Of course, this is disallowed by the OS, but if you have physical access to that device, you have and can access that data. That includes the database of all of your messages on that device, and the key to decrypt them.
PFS prevents someone using the key your device has on it from decrypting earlier cyphertexts. But if they have access to that key, they almost inevitably also have access to the database that signal keeps all of your messages in.
Thus PFS only works in practice if you delete the data from both the sending and receiving devices. PFS is useful, but it's usefulness is fairly limited in typical scenarios. But, if someone sniffed the cyphertext and then you read the message and deleted it/had disappearing messages on, and they later hacked your phone and got the key, you'd be safe and they couldn't decrypt the cyphertext they'd sniffed earlier.
It's just… …it's a really niche scenario, and most people (except the very paranoid) aren't regularly deleting every message.
@bastion > message database of **decrypted** messages that signal keeps around to show your history
What are you talking about ? Where did you get this from ?
There's a physical necessity to keep all of the information necessary to decrypt messages in the app's folder.
Anything the signal app shows you can also be seen by an app with access to Signal's data on that device. This is true of any E2E encrypted messenger service.
Of course, this is disallowed by the OS, but if you have physical access to that device, you have and can access that data. That includes the database of all of your messages on that device, and the key to decrypt them.
PFS prevents someone using the key your device has on it from decrypting earlier cyphertexts. But if they have access to that key, they almost inevitably also have access to the database that signal keeps all of your messages in.
Thus PFS only works in practice if you delete the data from both the sending and receiving devices. PFS is useful, but it's usefulness is fairly limited in typical scenarios. But, if someone sniffed the cyphertext and then you read the message and deleted it/had disappearing messages on, and they later hacked your phone and got the key, you'd be safe and they couldn't decrypt the cyphertext they'd sniffed earlier.
It's just… …it's a really niche scenario, and most people (except the very paranoid) aren't regularly deleting every message.