I did not know that about laser fault injection, at all. What practical uses has this technique found? Analysis of foreign military hardware? Cracking into secured systems?
traverseda 3 hours ago [-]
You know how android has safetynet? And how they're planning on making it so you can't run your banking apps unless they've approved your operating system?
Safetynet is a complex dance of crypto-keys, involving your phone and googles server. It generates a key from whatever state your uninitialized ram happens to land in (which is pretty consistent per chip and is a good source of randomness), uses that to generate a key, uses that key as a chain of trust to tell google whether or not you've modified your phone. It's some complicated stuff.
But if you can extract that key, or the source of data used to generate that key, you can trick safetynet fully and run your own software again. So how do we get that key?
Well maybe we can stop the safety processor from clearing that memory so we can read it? Glitch the chip when it tries to clear memory, so clearing memory fails. Or maybe we can glitch the part of the chip that keeps you from reading the region of memory where this finished key is kept, after it's already read that memory.
Basically you can use this kind of attack to make a chip sometimes fail when it goes to do or check something, including checking whether you should be able to extract a key.
This technique applies to reverse engineering as a whole, whether it's a state level actor reverse engineering military hardware, or you trying to run your own software on a device you own.
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Note the android example isn't practical, you'd need to like decap the main chip and a whole lot else. This technique can work with side-channel power-analysis, which can help you figure out exactly what data a program is using by looking at how much electricity it used to run.
Neywiny 3 hours ago [-]
And the best part? Instead of managing all my finance apps (bank, credit card, retirement, mortgage, etc), I just uninstalled them and go to the mobile site. It's not down for maintenance like my checking account app. It doesn't yell at me to update it like my credit card app. It doesn't prevent screenshots. They remember my login honestly more than the apps do.
rcxdude 2 hours ago [-]
There is a growing trends towards requiring an app for login to these systems, unfortunately (sometimes it's the only interface, sometimes you can log into a web interface but you need a code from the app to do so).
Neywiny 2 hours ago [-]
I have yet to see that happen on any of the 7 financial apps I use. But if it does, I'll just reevaluate where I keep my money.
tyromaniac 3 hours ago [-]
You can recover information about bits of keys, lowering the security of an implementation of a crypro algorithm, although in principle you could use it to recover other
The GaN hemt would make sense for a second board iteration where you drive the 75V straight through the diode with a very short (variable) pulse like in this EPC reference design:
That way the 1.4 Ohm resistor doesn't eat like 60-80% of the energy (40amps drop around 60V for an instant 240W in the resistor vs the foward voltage of the diode which is like 1.5V or so for the 60W peak).
so-gala-massey 5 hours ago [-]
The attack is on code that is not fault hardened. Had there been masked values and random delays used for every conditional and function call (plus call counters) this would have been impossible with his hardware.
However the expertise and diligence required to solve so many problems in building the platform is absolutely exceptional!!
LordShredda 7 hours ago [-]
I'm more interested in the 3D printed platform made to to hold up the chip and the fact that this seemed to be done in a garage. I thought anything laser related would require much more precision but the article has pretty much everything ordered online.
Building optically precise platforms with bearings and sliding surfaces is annoying and difficult. But it turns out you can do pretty dang well with applying force to bendy metal or plastic.
Below around 1 micron scales... sliding bearing surfaces can start to get less predictable, and more expensive. People get around the issue by combining different sets of precise and wide-range rough-motion systems. https://www.pi-usa.us/en/
There are also easier options if you spend some time with a specific use case. =3
Safetynet is a complex dance of crypto-keys, involving your phone and googles server. It generates a key from whatever state your uninitialized ram happens to land in (which is pretty consistent per chip and is a good source of randomness), uses that to generate a key, uses that key as a chain of trust to tell google whether or not you've modified your phone. It's some complicated stuff.
But if you can extract that key, or the source of data used to generate that key, you can trick safetynet fully and run your own software again. So how do we get that key?
Well maybe we can stop the safety processor from clearing that memory so we can read it? Glitch the chip when it tries to clear memory, so clearing memory fails. Or maybe we can glitch the part of the chip that keeps you from reading the region of memory where this finished key is kept, after it's already read that memory.
Basically you can use this kind of attack to make a chip sometimes fail when it goes to do or check something, including checking whether you should be able to extract a key.
This technique applies to reverse engineering as a whole, whether it's a state level actor reverse engineering military hardware, or you trying to run your own software on a device you own.
---
Note the android example isn't practical, you'd need to like decap the main chip and a whole lot else. This technique can work with side-channel power-analysis, which can help you figure out exactly what data a program is using by looking at how much electricity it used to run.
https://epc-co.com/epc/products/evaluation-boards/epc9172
That way the 1.4 Ohm resistor doesn't eat like 60-80% of the energy (40amps drop around 60V for an instant 240W in the resistor vs the foward voltage of the diode which is like 1.5V or so for the 60W peak).
However the expertise and diligence required to solve so many problems in building the platform is absolutely exceptional!!
Building optically precise platforms with bearings and sliding surfaces is annoying and difficult. But it turns out you can do pretty dang well with applying force to bendy metal or plastic.
For what purpose? Curious
There are also easier options if you spend some time with a specific use case. =3