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Coming from a background of developing audio hardware drivers for the Blackberry (I worked on the last generation and current generation before getting bored an

by rcfox 13y ago

Coming from a background of developing audio hardware drivers for the Blackberry (I worked on the last generation and current generation before getting bored and leaving a year ago), I can tell you that even if the baseband were able to turn on auto-answering, (I have no idea if that's possible, by the way) it wouldn't know how to configure the microphone and speakers to allow for recording or playback unless it convinced the application processor to help. If you are concerned about your Blackberry spying on you, there's a special "security plug" that you can insert into the headphone jack which will short all of the pins to ground, disabling the microphone. I assume other phones support this as well.

doubt_me 13y ago
Have never heard of a security plug before. where can I get one?
- antsar 13y ago
  I don't know where, but it sounds fairly simple to make: cut the connector off from an old headset, and solder all of the wires in it together. One of the wires (the uninsulated one) in there is ground, the other three are signal.
  - rcfox 13y ago
    Yeah, I'm not sure either. I don't see it in the official accessories store. antsar's correct though. It's simple to make one yourself. The nice thing about the security plug is that it's small; it doesn't look like your headphones' cable snapped off. :)
    - corin_ 13y ago
      If you don't trust the manufacturer who put the code into your handset, how can you trust that the security plug will always work (other than checking the internal wiring yourself)?
      - asadlionpk 13y ago
        plug the security plug and make a call to someone and see if they can hear you?
        corin_ 13y ago
        In the hypothetical in which the phone has been created to act as a bug, surely it would be easy to detect the security plug and disable the microphone for normal uses while leaving it enabled for hidden use. The security plug is only secure if the wiring means that when plugged in, software cannot access the normal mic - if software can access it, it can trick the user into thinking anything.
        nine_k 13y ago
        With the security plug plugged in, actual hardware, the microphone, is short-circuited and cannot produce any signal. That's the whole point. If you trust the wiring, of course ;-]
        corin_ 13y ago
        But that's my point - if you don't trust the people putting software into your phone, why would you trust the same people with what hardware they put in?
        jawr 13y ago
        Your argument about not trusting anything can be applied to... anything. It's not hard to make one yourself, so if you're that worried about security, don't use a third party plug.
        chris_wot 13y ago
        If you are really that paranoid, take out the battery when you aren't using it :-)
cnvogel 13y ago
Re: the security plug, I'll believe you that it might work for your line of devices, but in the schematics for the relatively few phones I've looked at there was always active selection on the phone pins. Think about it: you put normal headphones in the jack (no microphones, only tip, ring, sleeve): it will already short the mic input
- gbl08ma 13y ago
  If I put normal headphones in my phone's 3.5 mm jack, it recognizes that they don't have a mic and doesn't mute the built-in mic. So there are definitely some devices where this won't work.
tmzt 13y ago
There's no way to access the audio ICs from I2C or SPI on the BP? You might also need access to the PMIC to turn on the amplifiers, but most designs I've seen have access ports from both BP and AP. (This was on Motorola devices, Q and the EZX phones.)

by rcfox 13y ago

doubt_me 13y ago

Have never heard of a security plug before. where can I get one?

antsar 13y ago
I don't know where, but it sounds fairly simple to make: cut the connector off from an old headset, and solder all of the wires in it together. One of the wires (the uninsulated one) in there is ground, the other three are signal.
- rcfox 13y ago
  Yeah, I'm not sure either. I don't see it in the official accessories store. antsar's correct though. It's simple to make one yourself. The nice thing about the security plug is that it's small; it doesn't look like your headphones' cable snapped off. :)
  - corin_ 13y ago
    If you don't trust the manufacturer who put the code into your handset, how can you trust that the security plug will always work (other than checking the internal wiring yourself)?
    - asadlionpk 13y ago
      plug the security plug and make a call to someone and see if they can hear you?
      - corin_ 13y ago
        In the hypothetical in which the phone has been created to act as a bug, surely it would be easy to detect the security plug and disable the microphone for normal uses while leaving it enabled for hidden use. The security plug is only secure if the wiring means that when plugged in, software cannot access the normal mic - if software can access it, it can trick the user into thinking anything.
        nine_k 13y ago
        With the security plug plugged in, actual hardware, the microphone, is short-circuited and cannot produce any signal. That's the whole point. If you trust the wiring, of course ;-]
        corin_ 13y ago
        But that's my point - if you don't trust the people putting software into your phone, why would you trust the same people with what hardware they put in?
        jawr 13y ago
        Your argument about not trusting anything can be applied to... anything. It's not hard to make one yourself, so if you're that worried about security, don't use a third party plug.
        chris_wot 13y ago
        If you are really that paranoid, take out the battery when you aren't using it :-)

cnvogel 13y ago

Re: the security plug, I'll believe you that it might work for your line of devices, but in the schematics for the relatively few phones I've looked at there was always active selection on the phone pins. Think about it: you put normal headphones in the jack (no microphones, only tip, ring, sleeve): it will already short the mic input

gbl08ma 13y ago
If I put normal headphones in my phone's 3.5 mm jack, it recognizes that they don't have a mic and doesn't mute the built-in mic. So there are definitely some devices where this won't work.

tmzt 13y ago

There's no way to access the audio ICs from I2C or SPI on the BP? You might also need access to the PMIC to turn on the amplifiers, but most designs I've seen have access ports from both BP and AP. (This was on Motorola devices, Q and the EZX phones.)