Ask HN: Why do laptop chargers have data wires?

I taught them the trick about feeling the cable stiffness, I showed them a type-c cable without data vs one with data vs thunderbolt3 type-c. They just couldn't understand why it wasn't working until I showed them there was a physical and tactile difference in the cables.

Second, the same risk applies to every other device. Even if we eliminated charger docks and smart charging, we’d still have keyboards, mice, network adapters, storage, MFA tokens, etc. to worry about and that’s why your computer doesn’t blindly trust every device you connect any more. In 2004 you probably could have caused problems by presenting as a storage device with an auto run installer but now all you’re going to get are prompts.

The main reason a data connection of some kind is necessary, is because it allows for universal chargers (the U in USB means "universal", after all). The same charger can be used for a laptop charging at 36V and 5A (https://frame.work/blog/framework-laptop-16-deep-dive---180w...), and a phone which cannot tolerate anything above 5V and needs less than 3A. Even old "barrel plug" laptop chargers often already had some kind of data connection (for instance, old Dell chargers, which output a fixed 19V, could tell the laptop whether they are a 65W or a 95W charger, you can see it on the BIOS screen).

And for compatibility, the USB 2.0 wires (the negotiation described above happens on the separate CC wire) are also necessary. The way old USB-A phone chargers told the phone (which usually had a micro-B plug) they're a charger was through the USB 2.0 wires. The standard way of doing that is shorting both USB 2.0 wires together, but there are proprietary alternatives which do something else with these wires. A USB-C charger can charge these old phones through either a USB-C to micro-B adapter together with a USB-C cable, or a USB-C to micro-B cable.

> How do you approach this security threat? Or do you not do anything about it at all?

Frankly speaking, the security threat I'm more worried about is a low-quality or damaged charger accidentally putting unfiltered 127V AC into the USB port. The best way to protect against that threat, which also protects against the "charger is a malicious USB data device" threat you're worried about, is to carry and use only your own high-quality charger, together with a portable surge suppressor (which has a MOV with a fuse).

Several proprietary protocols (like Quick Charge) used the data lines to negotiate the power and voltage, then USB Battery Charging standardized a way to indicate being a charger through the data lines, and that was all before USB-C. So unless you were satisfied with very slow charging, the data lines were always necessary.

I just can't man, I fucking can't anymore with the Internet and people's need for everything to be spoon fed and assuming that everyone else has lost all information literacy.