PFS doesn't help if one of the parties is leaking information. And, I guess, in case of Snapchat, [at least most] leaks are from the participating users, not th

PFS doesn't help if one of the parties is leaking information. And, I guess, in case of Snapchat, [at least most] leaks are from the participating users, not the service. No amount of crypto would prevent malicious party from picking up a camera and taking a photo of the screen.