Re:Energizer battery charger contains backdoor
by noonespecial on Tuesday March 09, 2010 @05:34AM
(#1177940)
You can easily solve this problem by getting a usb cable without data wires. A few things I have came with these included with the charger. It pissed me off at first because they look like regular usb cables and I tried to hook up a disk drive. I marked them with a big X but soon realized how handy they could be when I wanted to charge a media player from a laptop I knew had some issues.
I've done surgery with a razor and some good shrink tube twice now to make more of these little gems.
Smarter devices like my Palm Pre actually ask if you want to let the host connect to them or just take power.
Re:Energizer battery charger contains backdoor
by Kliment on Tuesday March 09, 2010 @06:01AM
(#1177973)
If I understand the USB spec right, getting more than 100mA of power requires a negotiation with the host, thus data wires. There might be a market for a USB data blocker, a device that negotiates the 500mA output with the host and with the guest but does not pass through any data.
Re:Energizer battery charger contains backdoor
by noonespecial on Tuesday March 09, 2010 @06:22AM
(#1177991)
You are right. That's what the spec says. In reality, I've never found a single hub or host that actually does this. They mostly just dump somewhere between 300ma and 700ma right on the wire. The really advanced ones don't crash the all the ports on the whole machine if you short or overdraw a port. Actually, I think my macbook may get it right (i don't plug homemade usb junk into my macbook), but my toshiba I know for certain does not.
You've got a great idea though. A simple micro like a PIC or an arduino (atmel) could do this and get all kinds of neat data on the power flow as well.
Re:Energizer battery charger contains backdoor
by Dbug on Tuesday March 09, 2010 @07:45AM
(#1178077)
USB Specs are available here:
http://www.usb.org/developers/docs/
USB 2.0 in particular (10.9 MB zip file): http://www.usb.org/developers/docs/usb_20_122909-2.zip
USB data blocker - totally awesome idea. It could double as a protocol sniffer if it had a buffer.
Re:Energizer battery charger contains backdoor
by Kliment on Tuesday March 09, 2010 @09:10AM
(#1178237)
See, a blocker and a sniffer would have almost entirely opposite functions. Both are cool devices that could be built from essentially the same hardware, so you do have a point there, but I wouldn't combine the two. Too easy to end up doing the wrong thing and compromising your data.
Re:Energizer battery charger contains backdoor
by nazgulnarsil on Tuesday March 09, 2010 @06:06AM
(#1177977)
this is a great idea. market it to paranoid corporate IT for blackberries with sensitive materials.
Re:Energizer battery charger contains backdoor
by redcap on Tuesday March 09, 2010 @05:58AM
(#1177969)
No idea if no-data-wire USB cables are actually sold or do you have to roll your own?
Mind you, I find the point that there should be software for managing a battery recharger incredible.
Re:Energizer battery charger contains backdoor
by tedunangst on Tuesday March 09, 2010 @01:40PM
(#1179053)
When I plug my camera in to charge, it asks if I want it to go into disk mode. I can say no.
If your OS allows that, you need a better OS. Seriously, that's practically like having an OS that lets anyone on your LAN just SSH into your machine as root without a password just because they happen to be on the same subnet.
Re:Energizer battery charger contains backdoor
by wendroid on Tuesday March 09, 2010 @07:54AM
(#1178088)
man dma
Re:Energizer battery charger contains backdoor
by masomenos on Tuesday March 09, 2010 @10:01AM
(#1178367)
$ man dma
No manual entry for dma
Re:Energizer battery charger contains backdoor
by wendroid on Tuesday March 09, 2010 @12:31PM
(#1178851)
http://en.wikipedia.org/wiki/Direct_memory_access
And the description of how to exploit it
http://www.schneier.com/blog/archives/2006/06/hacking_comput...
The FireWire version http://www.storm.net.nz/static/files/ab_firewire_rux2k6-fina...
Re:Energizer battery charger contains backdoor
by wendroid on Tuesday March 09, 2010 @10:14AM
(#1178398)
get a better manual
Er, DMA isn't controlled by the TLB using the usual page table for access permissions? If not, PCs are ridiculously broken.
When wanting to charge a camera on an airplane, for instance, the user shouldn't be left to guess if his photos are going to be copied off the device.