The Thunderclap vulnerabilities

Posted Mar 7, 2019 15:42 UTC (Thu) by corbet (editor, #1)
In reply to: The Thunderclap vulnerabilities by dirkhh
Parent article: The Thunderclap vulnerabilities

I have a "USB condom" for USB A that, naturally, can be used with an A-to-C cable for charging (and I do just that). I haven't seen such a thing for native USB C yet.

The Thunderclap vulnerabilities

Posted Mar 7, 2019 15:52 UTC (Thu) by dirkhh (subscriber, #50216) [Link] (3 responses)

Hi Jon,

The problem with that is the USB A would limit you to something like 12.5W, right? And for a modern phone that's disappointing whereas for a MacBook Pro that isn't even enough to keep it from discharging while idle...

But yes, it sounds like we need a "USB C condom"...
Having that name actually gives me more interesting Google result - but from what I can see so far there have been quite a few requests similar to mine, but only USB-A versions appear to actually exist.

The Thunderclap vulnerabilities

Posted Mar 8, 2019 23:33 UTC (Fri) by flussence (guest, #85566) [Link] (2 responses)

Basic USB2 is limited to 5V@500mA - 2.5W. There's fast charging “standards” that go up to 900mA or more and most of them use passive components to signal it.

USB-C power negotiation however… makes the Linux x86 early-boot code sound simple and reasonable in comparison. Cables have their own CPUs, voltages aren't fixed, the hardware has to be prepared to put up to 100 watts into a tiny, fully bidirectional connector (and it's already infamous for doing it in the wrong direction too often - your phone will probably make a futile attempt to charge your laptop at some point). The technology's a disaster at every level.

The Thunderclap vulnerabilities

Posted Mar 10, 2019 17:35 UTC (Sun) by marcH (subscriber, #57642) [Link]

Probably the best technical blog about Type-C
https://plus.google.com/collection/0Vdov
moving to https://medium.com/@leung.benson

The Thunderclap vulnerabilities

Posted Mar 12, 2019 17:18 UTC (Tue) by k8to (guest, #15413) [Link]

I think this complexity doesn't prevent categorically the idea of a device which tries to limit the interaction to charging. However, it does make it challenging, and fairly hard to imagine proving it safe.

Which is probably what you were getting at.