3 ms·

Silly question based on my layman's understanding of the attack: Can you impede the extraction process simply by having your phone/tablet/laptop generate inter

Silly question based on my layman's understanding of the attack: Can you impede the extraction process simply by having your phone/tablet/laptop generate interference while the decryption process is happening? For instance, if your laptop is simultaneously playing music through its speakers, would the analysis still let them definitively pick out the signing key?

powerbutton65 11y ago
Valid question. You shift the burden from being a cryptography related problem to signal processing related problem.
- dogma1138 11y ago
  This isn't exactly a cryptography related problem to begin with, it's an implementation issue which inherently all side channels attacks are. This doesn't mean that you can't add some resistance against side channel attacks to your cryptographic algorithm but it will cost you quite a bit in terms of performance, and for the most part it's not where it should be. Better silicon should solve some of these issues, for example adding some additional isolation between the power section and the logic a small super-cap with decent in-band filtering might do the trick. As far as radiating EM goes I'm not sure what can be done but some more additional shielding and EM noise reduction should add some degree of protection. Most implementations will eventually be vulnerable to some type of side channel attacks, the complexity and cost-vs-benefit is important here. Launching an evil USB attack on the off chance of getting a key is most likely not very scalable, but considering that NFC/wireless payments for phones will become more and more common, and that crypto-currencies might actually end up being in common day use being able to extract keys during signing from EM leakage might just be the natural evolution of ATM/Payment Cards skimmer attacks. In the past 2-3 years we had various key extraction attacks using "strange" vectors like EM/audio extraction, temperature, cpu usage, cross platform cache attacks, these attacks can threaten cloud computing and mobile computing quite severely unless we can root them out and being to modify the devices and platforms to be much more resistant to them.
brohee 11y ago
You can add noise, which means they will have to collect more data and filter it in order to perform the attack. That cans make the attack harder, but not impossible.
arglebarnacle 11y ago
To me this sounds similar to the problem of how to execute a timing-based attack over a network with variable latency. The key is to make lots of requests very quickly. You can then statistically narrow down very small variations even though they're built on top of a larger trend signal like the network latency or a piece of music. As another commenter suggested, there may also be signal processing techniques to "mod out" the interference from the music (perhaps measured with a probe on the audio output?) and measure only what's left.

powerbutton65 11y ago

Valid question. You shift the burden from being a cryptography related problem to signal processing related problem.

dogma1138 11y ago
This isn't exactly a cryptography related problem to begin with, it's an implementation issue which inherently all side channels attacks are. This doesn't mean that you can't add some resistance against side channel attacks to your cryptographic algorithm but it will cost you quite a bit in terms of performance, and for the most part it's not where it should be. Better silicon should solve some of these issues, for example adding some additional isolation between the power section and the logic a small super-cap with decent in-band filtering might do the trick. As far as radiating EM goes I'm not sure what can be done but some more additional shielding and EM noise reduction should add some degree of protection. Most implementations will eventually be vulnerable to some type of side channel attacks, the complexity and cost-vs-benefit is important here. Launching an evil USB attack on the off chance of getting a key is most likely not very scalable, but considering that NFC/wireless payments for phones will become more and more common, and that crypto-currencies might actually end up being in common day use being able to extract keys during signing from EM leakage might just be the natural evolution of ATM/Payment Cards skimmer attacks. In the past 2-3 years we had various key extraction attacks using "strange" vectors like EM/audio extraction, temperature, cpu usage, cross platform cache attacks, these attacks can threaten cloud computing and mobile computing quite severely unless we can root them out and being to modify the devices and platforms to be much more resistant to them.

brohee 11y ago

You can add noise, which means they will have to collect more data and filter it in order to perform the attack. That cans make the attack harder, but not impossible.

arglebarnacle 11y ago

To me this sounds similar to the problem of how to execute a timing-based attack over a network with variable latency. The key is to make lots of requests very quickly. You can then statistically narrow down very small variations even though they're built on top of a larger trend signal like the network latency or a piece of music. As another commenter suggested, there may also be signal processing techniques to "mod out" the interference from the music (perhaps measured with a probe on the audio output?) and measure only what's left.