I am interested in countering limited targeted surveillance.
A light amount of research on the topic seems to indicate that white noise generators can counter some methods of audio surveillance, but specific details are scarce. Do any nanons know anything useful on this topic?
This sounds like a typical naive solution. Noise makes it harder to do these sorts of attacks, but there are methods to remove noise. The main benefit would be that they require more data in order to mount the attack, so it might be that only some details of what you say escape. But if the attack is mounted over a long time period, then this doesn't seem like a very large benefit. Better then white noise would be to have a device that makes speech-like sounds constantly. AM radio wouldn't work since they could easily remove it. But perhaps a speech synthesis program fed random words, or a bunch of podcast clips played in random order would do. The disadvantage to this method is that it would be more distracting to listen to than white noise. But remember that it will distract spooks even more.
This still isn't a perfect solution, and should be combined with acoustic and electromagnetic insulation to make as little audio escape the room as possible.
What are you trying to protect from? There's many different attacks based on acoustic (crypto)analysis. Or are you protecting only against surveillance?
Against surveillance, a true white noise will provide sound masking and make the audio harder to record. For that, see the PilferShush "active jamming":
https://github.com/kaputnikGo/PilferShushJammer
I don't think digital devices will be effective against a persistent attacker, though. White noise is generated (on digital devices) using PRNG and therefore can be predicted. A stochastic (true random) white noise generator will work better.
For acoustic (crypto)analysis, those two solutions will probably not be very effective. For example, this software records keyboard sounds (works as a keylogger):
https://github.com/ggerganov/kbd-audio
>>7830 The thing is: you will repeat the sound multiple times. Contrary to what cryptography does with PRNG (only once). You'll also need to create it in real time and even a good prng (arc4random, for example) will not be able to have enough entropy and might create deterministic numbers. So, if your threat model includes "military specialists", a PRNG will not work. For true RNG in digital devices, see OneRNG, Z1FFER (Open Random) and ChaosKey. Also the research OnChip is doing:
https://nanochanqwrwtmamtnhkfwbbcducc4i62ciss4byo6f3an5qdkhjngid.onion/g/4908.html#post5039
>>7824 >prng can be predicted
>>7832 >csprng is too slow
To produce random noise at 16 bit 44.1kHz PCM, we need a bitrate of 705,000. If we base our prng off of a hash function that outputs 256 bits, we need to do 7000 hashes per second. This is easy on even 20 year old hardware. Since we only need to mask voice, we don't need to bother with the high ~16kHz of frequency. That drops the necessary bitrate down to 128,000, and the hashrate to 500 hashes per second. The original 8008 could pull that off without a sweat. PRNG can in principle be predicted, but in practice this is the least of our concerns.
>>7832 >you will repeat the sound multiple times. Contrary to what cryptography does with PRNG (only once).
Could you explain what you mean by this?
>You'll also need to create it in real time and even a good prng (arc4random, for example) will not be able to have enough entropy and might create deterministic numbers.
Are you sure about this? My understanding is that a strong PRNG with 256 bits of security should be able to output a near arbitrary amount of pseudorandom data with a work factor of 2^256 to reverse.
>>7836 Very nice reply, thanks. Didn't do the math, but you're probably right.
>>7837 >Could you explain what you mean by this?
In cryptography you use random number one time for each binary file you're encrypting. In the case of white noise generation, you'll need to do that in real-time. This means you could (theoretically), apply signal averaging for denoising:
https://en.wikipedia.org/wiki/Signal_averaging
Leaking RF is likely to be of the most concern. Vibrations and sound likely require some sort of close proximity sensor to read, but that may be more of an issue nowadays due to many consumer tech items providing that opportunity, e.g. cellphones and personal voice assistants.
If you want to have a more secure location, you'll need to have conditioned/filtered power pass-through a grounded metal box. Said metal box would need to not have any windows and have another grounded metal box structure within it. The void area in-between would need to be monitored for RF/auditory leakage.
Something like a modified stamped-metal building with a modified refrigeration trailer unit placed in it, might work ok.
https://en.wikipedia.org/wiki/Tempest_(codename)
Suppose that it is not possible for me to move to a more secure location. Are there any methods of producing RF noise, similar to producing audible noise? Are there any deep sources of information you could point me to?
>not enough entropy
What about that OpenRNG or similar that was talked about in that other /g/ thread?
Could the entropy from one of those not be fed into a white noise generator?
>>7832 >if your threat model includes military
I wonder, do glowers seeking to protect themselves from
the glowers of other govs/orgs come here for knowledge?
>>7864 No deep sources needed. Look up how to build a spark gap transmitter. In many locations, these are illegal to operate due to the RF interference they cause.
>>7872 Which would also not be advisable, because it would draw the glowers to you, like moths to a light at night. You'd also have an army of old, curmudgeony HAMs trying to hunt you down.
>>7892 Well, sure, but I thought it was interesting that $50 of parts could jam large portions of RF spectrum. Picture spreading these across some city coordinated to spin up at the same time transmitting in primarily GPS, emergency services and cell phone frequencies, and enjoying the lulz. (This post brought to you for entertainment purposes only.)
>>8073 Hook up your jammer into an amplifier and jam a 20km radius around you.
Laugh at the cops who can't find out the origin of the jam because all they see is jam.
A directional antenna would be able to find the source. You could set up multiple emitters and have them randomly take turns, but even then it would only buy so much time.
A light amount of research on the topic seems to indicate that white noise generators can counter some methods of audio surveillance, but specific details are scarce. Do any nanons know anything useful on this topic?