triactual · HackerTrans

triactual

180 karmajoined قبل 5 سنوات

Regular-type dude.

comments

قبل 11 يومًاdiscuss

I have seen this play out with host devices with robust current limiting outputs. Sometimes it works for the connected device and sometimes the device sabotages itself when its own regulator turns on at say 3.6 V, drawing down the partially charged input cap below the regulator's UVLO and turning itself off again. Then the cap starts charging again and the cycle starts over. Depending on the host implementation, the burp mode may not reset without a full disconnection, at best leaving the connected device to sip a low average voltage and low current or persist in the above loop forever. Making sure this doesn't happen is more difficult than just implementing inrush limiting.

قبل 11 يومًاdiscuss

You need a soft-start circuit between the USB connector and your big cap. When you first connect the USB device, the cap has no charge (0V) so it appears as a short to ground to the host 5V supply. The result is a large current spike which can draw down the host supply below some functional threshold or even damage it. We could oversize the host supply to deal with a 25 A transient and add cost and introduce safety concerns or push the solution to the connecting device where the problem exists. The solution is to ramp the current up "slowly" over several ms using a transistor on the device side. While the transistor is turned on slowly, it isn't fully conducting, acting as a variable resistor. The transistor is dissipating power during this transition so it must be sized correctly and timing controlled deliberately. Hence why we want the same design to contain the cap, transistor, and ramp control. A typical circuit might be: connector->small cap->soft start->big cap->main circuit. The soft start feature is often just built into a voltage regulator since there's already a transistor and control circuitry there but you can also get a dedicated load switch if you only want ~5V. The 10uF requirement is a contractual agreement between host and device that ensures compatibility between devices. If you don't follow it, a sophisticated host may simply cut power when it sees the current spike and that would be the device's problem.

قبل 12 شهرًاdiscuss

The surface tension of the solder will pull them into alignment if the pad shape and solder volume are correct.

قبل 12 شهرًاdiscuss

If you read the article, you will see that the technology is specifically semiconductor design tools required for developing high performance computing that the PRC would use for nuclear weapons development. Can you do that with KiCAD? No.

قبل سنتينdiscuss

Weren’t the Intel CPUs made in the US?

قبل سنتينdiscuss

It would be for indefensible decapitation strikes. A world leader who would launch a surprise first strike is almost certainly narcissistic enough to be susceptible to blackmail by a threat on their own life. A world leader who is not concerned with their own life but that of their countrymen will likely not launch a surprise first strike and so MAD still works.

قبل 3 سنواتdiscuss

The isotopic content of the water matters too. Boiling point are not used to calibrate thermometers though. Freeze points and triple points are used for temperature calibration. And outside of a primary standards lab, it’s usually just a transfer standard (another, more accurate thermometer).

قبل 3 سنواتdiscuss

Sorry, I think I misunderstood your original comment - we’re having the same thought with MITM. Definitely more technically challenging but much harder to detect.

قبل 3 سنواتdiscuss

My point is that no matter what you tell the OS, there will still be one more device connected than expected. If you plug in a keyboard and two are suddenly connected, it’s still very noticeable. This counting problem is occurring at the hardware level in the USB hubs and host. The attacker needs to compromise an external hub to behave like a USB protocol analyzer capable of intercepting and modifying data seamlessly in order for an attack like this to be anything other than trivially detectable. Fitting something like that into an existing enclosure means writing lots of low level code and embedded hardware design which is a different level of difficulty.

قبل 3 سنواتdiscuss

Yeah, this is more of a UI problem that could be solved with a little effort. I would be concerned about a device that replaced the hub itself rather than simply adding a function. The core issue is that a system can always notify the user of newly connected devices (Windows seems to about half the time). But a malicious MCU emulating a hub and compromising or stealing data at the USB protocol level could appear exactly as expected. It could key log, inject, etc., undetected because it doesn’t have to interact with kernel drivers as anything other than the expected hub.

قبل 3 سنواتdiscuss

Maybe I’m missing something but these USB attacks require interaction with kernel drivers so if you plug in a dock that then presents mysterious storage or HID functions, you’re going to know.

قبل 4 سنواتdiscuss

They all leverage the masses. That’s the whole point. Otherwise it’s just a coup.

قبل 4 سنواتdiscuss

No, you are exactly backwards. Did the People’s Revolution win or did the students win? I seem to remember that the students were run over by tanks. Probably not being driven by highly educated PLA commanders.

قبل 4 سنواتdiscuss

With ST, specifically, I'm not seeing a lack of Silicon but a lack of lead frames. The recent shutdowns in China caused several batches of lead frames to expire unused, creating a big gap moving through the supply chain. Chip-scale packages have better availability.

قبل 4 سنواتdiscuss

What really kills me is that none of the complainers have any experience designing consumer hardware let alone running a business that sells those designs. Owning lots of hardware whose design is beyond your ken is not the same thing as designing hardware and running a profitable hardware business. Everyone will be sad when Framework doesn’t make it and no one will reflect on these BS comments and the unnecessary ill will they sow.

Sometimes there is no conspiracy to rip off all ten people off who want to repair their board. Like they’re going to spend any time figuring out how to make an extra $3k. They might just be trying to keep their IP and stay around long enough to make good on the things they did promise: modular hardware.

قبل 4 سنواتdiscuss

It’s genuinely terrifying. There seems to be no recognition that you cannot have labor unions and environmental protections with out tariffs to even the playing field with less scrupulous countries. We are rapidly approaching a time where only the military industrial complex retains any manufacturing expertise.

قبل 4 سنواتdiscuss

This is pure fantasy. Minimum wage in the US is 2-10x what it is in low cost regions. Not even touching regulations. US experts travel to those regions to hand-hold every step necessary in order to make any product not forced to be built in the US by taxes or regulation. I did this for years and I hate it. I have worked for years in both American and foreign factories and I can assure you that they can automate just as well so there is no hope without government intervention in the form of tariffs. US labor currently competes on a global market.

قبل 4 سنواتdiscuss

Not flame proof though. You don’t want to put flammable things in something like a computer case that will be running unattended. I get that people do this stuff all the time with no issue. Just know the risks before taking them.

قبل 4 سنواتdiscuss

UL94-V0 polycarbonate sheet or fish paper. Heatsink could easily get over the glass temp of common 3D printing materials like PLA or PETG.

قبل 4 سنواتdiscuss

Previous comment means materialism as defined in philosophy. Not materialistic.