Comment by Steltek | Hacker News Reader

Comment by Steltek | Hacker News Reader

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Hang on, it's not like type-A where it's just a single parameter (1.1/2.0/3.0). A USB-C cable has tons of potential features and a port has possibly more features still.

- Protocol: 3.0 or 3.1

- Power: QC, PD, or none of the above; how many watts

- Alt-modes: HDMI, DP, TB3

- Chipset features: UAS

Once you've assigned all of these to a color, the higher end cables are going to look like a pride flag or something. The solution is really not that simple at all and it's far from guaranteed that once adoption picks up that you can just assume your device/cable combo "obviously" supports what you want.

On top of all of this, construction of USB-C cables are far more complex than your run of the mill cable. They're active devices with apparently absurdly tight tolerances. Did everyone forget about the Benson Leung's spreadsheet of killer cables? Even if the industry can figure out a user friendly branding, it's still a roll of the dice for whether you'll fry your laptop.

Lastly, USB-C seems like a mandatory weakening of security. In a few years time, you won't have any other choice but USB-C and now suddenly any random charger (or cable!) could be the easiest rootkit ever deployed. The cute pen testing exercise of dropping USB thumbdrives with backdoored Word docs is going to get a lot more serious. I wonder how long until we have "hardware firewalls" that attempt to rein in USB-C devices. We're past the "USB condom" at this point.

> Did everyone forget about the Benson Leung's spreadsheet of killer cables?

Link: https://docs.google.com/spreadsheets/d/1wJwqv3rTNmORXz-XJsQa...

Previous discussion (710 days ago, 397 comments): https://news.ycombinator.com/item?id=10508494

> QC, PD, or none of the above

not a property of the cable

> Alt-modes: HDMI, DP, TB3

not a property of the cable

> Chipset features

not a property of the cable

> They're active devices

Only long-length thunderbolt cables are active.

> Benson Leung's spreadsheet of killer cables

The check there is "does this A-to-C cable say it's A-to-C, or say it's a 3 amp source". If you use it with an incorrectly designed charger, the charger could get damaged. "Killer" is not really fair, because the only "fry your laptop" situation was an instance of a wiring mistake that could happen on any kind of cable.

cesarb is right, you can represent it as max protocol and max current, and type-A cables have approximately the same setup.

Hang on, I thought there were only two main axis for a USB-C to USB-C cable: maximum protocol (3.1 Gen 2, 3.1 Gen 1, 2.0) and maximum current (3A, 5A). Also, wouldn't most USB-C cables be passive, and the choice of alternate mode be left to the endpoints? I don't think a passive cable cares whether the wires are being used to carry DisplayPort, HDMI, or something else.

The maximum current isn’t at 5A anymore, as many USB-C cables now support 100W USB power delivery

Isn't 100W USB power delivery 5A at 20V?

Good point, yeah. For some reason I had assumed they’d stick with the same 5V as always, but you’re right, they use 20V for PD.

Can we not have a power-only USB-C condom / datawall?

Yeah, I don't see why not. USB-C PD negotiation is not done over the USB 2.0 data bus.

Surely if negotiation of any kind is performed, then there's logic on either end, and there's immediately a new threat surface?

Not a rhetorical question; I'm not well informed in this field.

Indeed, but that could be much more constrained than appearing as a new keyboard and typing "sudo rm -rf /" or the equivalent...

easy, green cables for 'all of the above.'

then each year as new standards are added you make the shade of green slightly lighter. then you just need to know what shade of green your use supports and make sure you cable and ports are as light or lighter.

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