Hil Will, Your points are valid that PKI is not a panacea. Code signing has limitations -- I agree.
Without extensive code review, code signing of any sort is not a guarantee that the application isn't doing something malicious - agreed. Signing under a CA's certificate, likewise, is not a guarantee of any kind of verification that the application isn't misbehaving - again, agreed. But that's not ultimately the point. What code signing under someone else's umbrella of trust does is give you the _possibility_ of setting up a system where trust can be systematically revoked in automated fashion when malicious activity is performed under false pretenses within an application that has a signature. I think that malicious activity can be clearly and cleanly defined (e.g. your information is released without your knowledge, or you are subject to monetary costs or other damages that you did not agree to). I'm not talking about curtailing "distasteful" content. I'm talking about mechanisms for controlling clearly dangerous applications. I also agree with you that this is not just an Android issue, but of every general purpose computing system. When it comes to smartphones, however, other platforms have come up with some way of mitigating the potential impact of rogue applications. We can argue the merits and drawbacks of each all day, but the point is that they have something that has made a reasonably large number of intelligent people comfortable. The fact that Android is operating as a smartphone platform but doesn't have an answer to this other than crowdsourcing is basically saying to handset manufacturers, network operators and end consumers that they're on their own and it's their own damn fault if something awful happens to their information, phone bill, or the networks on which they run. Signing + CA is not the complete solution, by any stretch of the imagination, I agree, but something like it could be a start. On the desktop side, relying on end users' knowledge has given us lovely things like ILOVEYOU and botnet DDoS attacks on Estonia. Why repeat that joy on a promising platform by not coming up with an alternative? -jfr
