11 ms·
RSA Key Extraction via Low-Bandwidth Acoustic Cryptanalysis
- sillysaurus2 13y agoPlaying loud music when encrypting/decrypting/typing in your password will defend against acoustic attacks, right? This other type of attack, however, isn't so easily guarded against: Beyond acoustics, we demonstrate that a similar low-bandwidth attack can be performed by measuring the electric potential of a computer chassis. A suitably-equipped attacker need merely touch the target computer with his bare hand, or get the required leakage information from the ground wires at the remote end of VGA, USB or Ethernet cables. This serves as a reminder that it's pretty much impossible to defend against an attacker that has physical access to your box.
- kevincennis 13y ago> Playing loud music when encrypting/decrypting/typing in your password will defend against acoustic attacks, right? Probably. The answer to Q11 says "The interesting acoustic signals are mostly above 10KHz". They don't say what the high end of the range is. But I would guess that sufficiently loud music (which usually contains frequencies up to about 22kHz) would mask the sound generated by the CPU.
- pbsd 13y agoFrom the article: Noisy environment. One may expect that placing the machine in a noisy machine will foil the attack. However, the energy of noise generated in a typical noisy environment (such as outdoors or a noisy room) is typically concentrated at low frequencies, below 10kHz. Since the acoustic leakage is usually present well above this rage, such noises can be easily filtered out during the data acquisition process using a suitable high-pass filter (as we did in our experiments). Also, the signal would be observe during any pauses in ambient noise (e.g., music). Note also that the attacker may, to some extent, spectrally shift the acoustic signal to a convenient notch in the noise profile, by inducing other load on the machine (see below). Thus, a carefully-designed acoustic noise generator would be required for masking the leakage.
- kubiiii 13y ago"Thus, a carefully-designed acoustic noise generator would be required for masking the leakage." Like dubstep.
- sliverstorm 13y agoEDM to save the world (by blocking government snooping)! http://www.youtube.com/watch?v=Da4V5vKcGl8 http://www.youtube.com/watch?v=Da4V5vKcGl8
- kubiiii 13y agoThey have an electribe ER1 and they modulate so that's gold.
- sliverstorm 13y agoof COURSE we can f@cking modulate this
- kevincennis 13y agoI saw that too, but I think they sort of side-step the issue of music. The bit about noise typically being below 10kHz doesn't really apply to most music. If you go run pretty much any modern record through a spectrum analyser, you'll see tons of content above 10kHz. Anyway, I'm certainly not claiming to know with any certainty that loud music would work as a preventative measure against this kind of attack. I just don't think the paper sufficiently proves that it wouldn't be.
- JonnieCache 13y agoThis is complicated by the human ear's variation in loudness perception over the frequency spectrum, and the effect this has on music. The stuff over 10k is typically mixed quieter than the stuff under 10k, though it doesn't sound that way. Records with lots of energy above 12-13khz tend to sound pretty awful. https://en.wikipedia.org/wiki/Equal-loudness_contours https://en.wikipedia.org/wiki/Equal-loudness_contours EDIT: also pitch is logarithmic with respect to frequency. 8khz sounds really high pitched.
- dfox 13y agoIn my opinion, changing software in response to emissions (be it audio or EMI/RFI) and power side-channel attacks is mostly futile and correct solution involves just making sure by means of physical security and/or shielding that attacker cannot access places where it's possible to implement such attacks. On the other hand timing attacks are something that anyone implementing anything security related has to be aware of and actively prevent as they can be conducted from mostly anywhere. On the other hand measurement of potential on chassis seems interesting as that can possibly be measured pretty far away (eg. PC -> STP cable -> Cable modem -> CATV).
- shabble 13y agoAh, the Maginot Line[1] argument. Given the sheer number of possible emissions channels, are you proposing they all be universally protected against in hardware? Or that there should be special classes of 'protected against $FOO' hardware for specific threats? The concept of defence-in-depth suggests that you should take all[2] possible measures to avoid sensitive data leakage. If an attacker does get into your secret computer-bunker, but can't get past the cage or case-level defences, they could potentially still use such an attack as this. Also, how do you test that your shielding is working? The paper notes that their probable noise source was a faulty electrolytic capacitor, which presumably wasn't [as] faulty when QA'd at the factory. So you'd need to periodically retest, which could get pricey fast. Likewise, the engineering tradeoffs of shielding everything make it pretty impractical for mobile/portable devices, or ones that might be used in unsecured areas. The main issue I see is that if this (or similar improvements) is truly something that could be implemented with a mobile phone or small MEMS microphone bug in the general vicinity, it's potentially cheap enough to make it not just a "how do I protect against the NSA?" problem, but one within the means of corporate or organised crime espionage groups. [1] https://en.wikipedia.org/wiki/Maginot_Line https://en.wikipedia.org/wiki/Maginot_Line [2] well, as many as economically feasible anyway.
- sneak 13y ago> and correct solution involves just making sure by means of physical security and/or shielding that attacker cannot access places where it's possible to implement such attacks This is addressed in the linked page.
- hawkharris 13y agoPlaying loud music when encrypting/decrypting/typing in your password will defend against acoustic attacks, right? I recommend "Wrecking Ball" by Miley Cyrus. The strength of the attacker's cryptanalysis will be moot because no one will go near you.
- mathgladiator 13y agoor... it may increase people's interest in you, you know, for national security.
- hawkharris 13y agoWell, by Bradley Manning's account, he listened to Lady Gaga while leaking classified military documents, so maybe hit pop songs are not as innocent as they seem. :)
- BrandonMarc 13y ago"Puberty Love" can be an ... um ... lethal option, too. http://en.wikipedia.org/wiki/Attack_of_the_Killer_Tomatoes http://en.wikipedia.org/wiki/Attack_of_the_Killer_Tomatoes
- venomsnake 13y agoIt won't - you find the tracks with shazam and then just subtract them from the recording.
- hosh 13y agoSo a scenario would be what, when two people bring their laptops to do a deal via Bitcoin?
- tedunangst 13y agoThe attack requires the victim to encrypt/decrypt many chosen messages, no? Configure your laptop to only encrypt or decrypt messages when you want it to.
- ams6110 13y agoSome people have GPG configured to sign every email they send. Would that be enough activity to compromise the key?
- tedunangst 13y agoNot if the attacker doesn't control the contents. They would need to send you the email, and then you would need to open/decrypt it while they're listening. afaik.
- lhgaghl 13y agoUhh... When people say physical access to your box, they mean someone can physically tamper with it in arbitrary ways. This is not the same as being near the box. Otherwise we would just say that all phones/laptops are insecure.
- BrandonMarc 13y agoThis serves as a reminder that it's pretty much impossible to defend against an attacker that has physical access to your box. ... or is able to hack into your phone.
- r0muald 13y agoImportant stuff: > Q9 How vulnerable is GnuPG now? We have disclosed our attack to GnuPG developers under CVE-2013-4576, suggested suitable countermeasures, and worked with the developers to test them. New versions of GnuPG 1.x and of libgcrypt (which underlies GnuPG 2.x), containing these countermeasures and resisting our current key-extraction attack, were released concurrently with the first public posting of these results. Some of the effects we found (including RSA key distinguishability) remain present.
- bhouston 13y agoJust to be clear, I believe this is from 2004.
- longwave 13y agoThis was originally presented was in 2004, but since then has been refined in a number of ways. The detailed paper that includes the full key extraction attack was only released today, coinciding with the GnuPG security update that mitigates against the attack.
- gwern 13y agoIt took 9 years to fix GPG?
- edwintorok 13y agoGnuPG 2.x wasn't vulnerable, just the old 1.x: http://lists.gnupg.org/pipermail/gnupg-announce/2013q4/000337.html http://lists.gnupg.org/pipermail/gnupg-announce/2013q4/00033... "GnuPG 1.4.16 avoids this attack by employing RSA blinding during decryption. GnuPG 2.x and current Gpg4win versions make use of Libgcrypt which employs RSA blinding anyway and are thus not vulnerable."
- tripzilch 13y agoRSA blinding seems to protect against timing attacks, how does RSA blinding protect against this acoustic attack?
- wrongc0ntinent 13y agoThe single coolest thing in the paper (other than Shamir's name): "On many laptops (e.g., most Lenovo ThinkPad models), the chassis potential can be easily reached by a human hand, through metal connectors and conductive coating on metal surfaces. Thus, an attacker can measure the chassis potential by merely touching the laptop chassis with his hand. Surreptitiously, the attacker can simultaneously measure his own body potential relative to the room’s ground potential, e.g., by having a concealed differential probe touching both his body and some nearby conductive grounded surface in the room. Perhaps surprisingly, even this circuitous measurement offers sufficient signal-to-noise ratio for the key extraction attack."
- dfox 13y agoI wonder whether this is specific to laptops (running from battery or otherwise not grounded) or if it also works with properly grounded desktop computers. My HP notebook from ~2000 had measurable (although very high impedance) 110V AC between exposed metal parts and PE in wall outlet when connected to charger. Modern thinkpads (and probably all non-Apple laptops sold in Europe) does not seem to have this problem as ground is connected through in charger, not only AC coupled to both hot and neutral.
- dfox 13y agoI have been finally able to download and read their full paper and it seems to answer this question: they observe that grounding thru AC charger does increase SNR of measured signal.
- pilsetnieks 13y agoMacbooks can be grounded, too. The round metal thing that's holding the plug in place also serves as a connection for ground. It is moot if you're using the small plug which doesn't have ground but if you connect the cable instead of the plug, or use a UK plug, the computer is properly grounded.
- deleted 13y ago[deleted]
- cmansley 13y agoRandom comment: Could similar attacks be used to extract the private key for Bitcoin accounts?
- sneak 13y agoThese attacks are specifically for the operations involved in repeated use of long-term RSA keys, and Bitcoin uses ECDSA keys a relatively small number of times, so the attacks would be materially different. However, I would not bet against the fact that your machine outputs "compromising emanations" (be they acoustic or RF or otherwise) leaking _some_ information about your bitcoin keys. There is less opportunity to execute such an attack in the bitcoin universe, though, as bitcoin-qt doesn't reuse keys that much. (When you send a payment, the "change" difference is sent to a new key.) It's something to think about, but the attack surface is a lot smaller. Perhaps there's something specific in the ECDSA algorithm that may make it easier or harder? I don't have the requisite mathematical understanding of elliptic curves to know how they're executed in-CPU.
- drakaal 13y agoThis is a really well written fake. Use some common sense. Are you only doing one thing on your computer? No. Does your Memory vibrate when the data is stored? No. Can data be transferred via acoustics over a 2 conductor 16 gauge wire at the speeds memory is accessed or is sent to the CPU? No. Think of something you have heard "hum". Is the noise pattern of your Amp and another the same if the "hum is anything other than 60hz? No. Because manufacturing tolerances are not such that the flaws are the same. This is really great FUD. Likely designed to get People to think that they are constantly at risk, and have the CIA and FBI spend billions buying acoustic shields for their computers. If this is real. And does work, fine, just run a background task that puts multiple random RSA's through the paces in alternate threads so the extraction can't take place because of garbled data. EDIT: Apparently I forgot that HackerNews You get downvoted if you present common sense in face of a fallacy that those with limited understanding want to hold true, as seen by the mass of links to wikipedia made by those with out the foggiest about audio, capacitance, RSA, or Electrical engineering. -Brandon Wirtz SMPTE
- Groxx 13y agoApparently you didn't read it, but nevermind. Specifically this: >just run a background task that puts multiple random RSA's through the paces in alternate threads so the extraction can't take place because of garbled data. Adding randomness does not remove detectable, statistically-significant information. It just takes more trials to extract it. This is the basis of many side-channel attacks. Super-trivial example: if you roll a super-weighted die and it shows 6 every time it's obvious, but if it's only barely weighted it'll still be detectable with enough rolls, to the same level of confidence (since getting 6 one hundred times in a row is not impossible with a fair die).
- drakaal 13y agoRoll a 24 sided di a 6 sided di a 12 sided di and 2 dozen di picked of random sizes each roll, and a Di that always rolls 6 but is only included once every Random rolls. Determine a method given only the SUM of the di to determine the value of the weighted di.
- __alexs 13y agoThis is the patch they used to mitigate it afaict. http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=commitdiff;h=dec048b2ec79271a2f4405be5b87b1e768b3f1a9 http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=co...
- Lagged2Death 13y agoUsing multiple cores turns out to help the attack (by shifting down the signal frequencies). I don't understand how this would be, maybe because I don't understand what they mean by "using multiple cores." You'd think that running a decoy thread on another core would mask things pretty effectively.
- cradle 13y agoI understood it as the general tendency for more cores resulting in lower per core clock speed. The lower the clock speed, the more you can hear in the audible frequencies.
- p4bl0 13y agoDisclaimer: I never worked with the sound side-channel, so maybe what I'm going to say is not entirely true, but the general idea should be right. Actually I think the job of the other core would be more difficult than just doing random noises to mask the noise from the actual secret computation. Simply doing random computations (and thus, random noises) of the other core is not effective since random noise would "easily" be canceled using statistical tools (for instance, looking at the variance of the data instead of looking at it directly will already reduce some type of noises). What would be more effective would be to balance the noise for instance, maybe running the same computation with opposite data would balance it more effectively. To picture what I'm saying better, here is a completely fanciful example (just to provide an idea). Imagine that during the RSA exponentiation (where the private key is exposed), the operation that is done when the bit of the secret key is 1 makes the sound "s_s_" and when it is 0 the sound is "_p_k". If you do the the same computation as the secret one on the other core exactly at the same time, but with the opposite secret key, then whatever the key is the attacker will always ear "spsk" at each clock cycle. And that will be harder to attack than random noises (but is also more difficult to achieve, of course). That said, I don't know why the use of multiple cores would help the attack (but I didn't read the paper, just a few sample of the linked web page).
- Sami_Lehtinen 13y agoNobody mentioned TEMPEST yet in this comment thread. It's old (60s) but very interesting stuff. https://en.wikipedia.org/wiki/Tempest_%28codename%29 https://en.wikipedia.org/wiki/Tempest_%28codename%29 It includes acoustical leaks as one side channel. Also see: http://www.nsa.gov/public_info/_files/cryptologic_spectrum/tempest.pdf http://www.nsa.gov/public_info/_files/cryptologic_spectrum/t... It's cool that they were able to demonstrate it that well.
- hardwaresofton 13y agoCame in here to make this exact comment -- the amount of things looked into as ways to leak secrets was insane, even going as far as detecting screen radiation IIRC.
- midas007 13y agoCheck out this researcher's papers: http://www.cl.cam.ac.uk/~mgk25/ http://www.cl.cam.ac.uk/~mgk25/ esp. "Optical Time-Domain Eavesdropping Risks of CRT Displays"
- artificialidiot 13y agoA good enough solution might be using appliances designed with older cpus with little to no power management features but it is only practical for high stakes stuff like military comms I guess.
- jgalt212 13y agoI really want to call B.S. on most of their claims, but I withhold any judgement until there is a live demo performed. Have they announced a timetable for a live demo?
- p4bl0 13y agoJust go to any conference about cryptosystems' implementation security (like CHES), or to any exhibition on this topic (like CARTES) and you will be bluffed by demos of side-channel attacks, which are very real.
- afsina 13y agoThis sounds like BS, smells like BS.. But then again he is Shamir.. Still I think it is BS
- eyeareque 13y agoIf three academic types can come up with this, just imagine what the NSA or other foreign intelligence groups can find with a budget like they have. Interesting for sure.
- chromano 13y agoIf that attack is available for us to know, I wonder what can possibly be happening inside NSA? I even wonder how these big guys/heroes like Julian and Snowden feel when they find out about it. I mean, maybe they just don't care about the stuff they have being accessed without their consent, it is supposed to be released anyways, but what about their conversations that are supposed to be highly confidential?
- bsaul 13y agoI've read the linked document, but this feels like magic to me. Is the general idea something like : i can hear the CPU is doing 10 additions, then 20 substractions, twenty times in a row, so i can tell by knowing the algorithm used that the CPU is computing a public key and that it must be between 1 billion and 1.5 billion ?
- aidenn0 13y agoNo, more like the CPU will, in some cases, need to do more work if the key is X and less work if the key is Y, and we specially craft our plain-text to have many X/Y pairs as possible, so that we can hear the capacitors working harder when decrypting.
- BrownBuffalo 13y agoWhat's interesting are old school spy acounstic methods. http://en.wikipedia.org/wiki/Laser_microphone http://en.wikipedia.org/wiki/Laser_microphone <-- great primer. This played out in micro surface vibration in a cup of coffee in the movie Eagle Eye (terrible movie btw). Either way, kind of a neat way to spy on embassy windows from a far w/o even having to be in the room. A little off topic was the KGB's bugging a government office with passive radio transmission - virtually undetectable http://en.wikipedia.org/wiki/Thing_(listening_device) http://en.wikipedia.org/wiki/Thing_(listening_device) This stuff is so damn cool. :)
- abvdasker 13y agoWhen I started reading I thought this must be a joke. As a dev with what I like to think is a solid understanding of computer hardware I don't often think of new tech as spooky/sci-fi-esque, but this is so unbelievably cool. I have no words.
- midas007 13y agoI remember being able to hear a program run on an HP 32S (RPN) by placing it up to my ear, so this isn't surprising.
- deleted 13y ago[deleted]
- p4bl0 13y agoIt seems you don't know the first thing about the topic you are talking about. Side-channel attacks are very real. I'm working in a lab which focuses precisely on cryptosystems' implementation security, and I for instance saw someone extract the secret key of an AES running on a last gen smartphone (with multiple cores etc. as you describe). The attack was using an antenna (which listened to electromagnetic emanations rather than sound, but that's a detail, it is also possible to do that with power consumption, timing…) which was simply put near the screen of the phone. That was not supposed to be very impressive, it was during an exhibition just as a fun demo to attract people to the stand which did it. And moreover, about what you say in your criticism, cryptographic computations often take place on embedded systems like a credit card where you have less noise and slower computations, which makes it even easier to perform this kind of attacks.
- afsina 13y agoWe are talking about acoustics, sub 100khz signals. They are not talking about catching emanations from sound codecs or key strokes they are talking about CPU instructions for crying out loud. There is certain loss of information when we are talking about catching x86 instructions happening in 3Ghz. Paper does not really explain this.
- X4 13y agoWithout taking party, I am deeply impressed at an increasing rate and with honest respect to the ingenuity of the research that's coming from Tel Aviv, Israel and from Switzerland. There is no other country except the USA which makes such leaps in technological progress. That's my honest image of the research. I'm personally reading many of their publications and from various other journals too.
- Sami_Lehtinen 13y agoFixed GnuPG 1.4.16 version released: http://lists.gnupg.org/pipermail/gnupg-announce/2013q4/000337.html http://lists.gnupg.org/pipermail/gnupg-announce/2013q4/00033...
- kken 13y agoThis is really impressive work. After skimming through the detailed paper it looks as if they are not picking up sound emitted from the CPU itself, but from the switching power supply circuit. The frequency variation is caused by load differences. So they are in fact doing an indirect power analysis. A switching power supply will always change frequency as a reaction to variations in supply current, this is inherent to its design. I also believe that it will be very difficult to "muffle" all the inductors and capacitors as they are subjected to very high pulse loads. Magnetics will always find a way to emit sound... It's interesting to note that the biggest difference seems to be between register and memory instructions. This seems reasonable as memory instruction may, in the worst case, require powering the external bus, which is very power hungry. This will only get worse in future CPUs, as more and more clock gating is introduced. So, I guess some countermeasures could be: - If the CPU supports SMT or HT, load the other cores with a thread accessing random memory positions. - Optimize the RSA code so that it's memory access and runtime pattern does not depend on the key or clean text. - Try to localize the RSA code as much as possible to reduce memory accesses. If memory access is required, do it all at once, for example by swapping entire cache pages. Some of these are highly CPU dependent.
- gwu78 13y agoWhat about computers located in the datacenter, next to other people's computers?
- oakwhiz 13y agoSome motherboards have programmable/adjustable VRMs. I wonder if the settings can be changed to mitigate the threat.