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Security Technology

Breaking RSA Keys by Listening to Your Computer 186

An anonymous reader writes "Adi Shamir and crew gave a talk on preliminary results in extracting a private RSA key just by listening to the computer!. Similar to power analysis and LED leakage, this is a non-invasive, side channel attack that may have applications to tamper-resistant systems. It appears to be related to noisy capacitors on the motherboard, an effect which has been observed when CPU power saving is enabled on laptops."
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Breaking RSA Keys by Listening to Your Computer

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  • by Anonymous Coward on Saturday May 08, 2004 @12:09PM (#9093907)
    No power saving for me! My encrypted porn is far too important.
    • easy to fix, simply encase your machine in some foam... the noise is actually made by the attraction between the conductors in the capacitors, as the capactitors get charged/discharged the (usually rolled up aluminum foil with some acid soaked insulator in between) the conductors vibrate a little. Cheaper capacitors vibrate more (more loosely wound->more space to vibrate !). For maximum security use tantalium caps ! (fire hazard, great pyrotechnics if you overload them).
  • The following demonstrates some preliminary results in the analysis of acoustic emanations from personal computers, showing them to be a surprisingly rich source of information on CPU activity.

    Does it mean that people can get my private key by actually "listening" to my box? It would be great if anyone can provide more information regarding this. It's kinda freaky!!!
    • No (Score:5, Informative)

      by Transient0 ( 175617 ) on Saturday May 08, 2004 @12:25PM (#9094012) Homepage
      at best, they have shown that they can detect differences in the types of instructions the processor is executing by listening to the sounds of the capacitors. It is a long way from there to the point where they can extract the key itself from the information. In fact, I would venture that the data is far too noisy (haha) for any significant part of the key to ever be extracted, reagardless of the amount of computational power thrown at the problem. What they might be able to do however is use the information gleaned to eliminate large swaths of the set of possible keys. This could make cracking the key by conventional means a computationally easier task.

      So, in all, this paper is not insignificant, but it's also not a reason to completely give up on security or to install a cone of silence around your computer.
      • Re:No (Score:3, Funny)

        by lpangelrob2 ( 721920 )
        So, in all, this paper is not insignificant, but it's also not a reason to completely give up on security or to install a cone of silence around your computer.

        I'm not sure that I could fit this [] around a computer in the first place.

      • No no (Re:No) (Score:5, Informative)

        by po8 ( 187055 ) on Saturday May 08, 2004 @01:39PM (#9094376)

        Uh, no. Your analysis runs contrary to cryptanalytic principles and the history of these sorts of attacks.

        If you spot me 1 bit of key information, you have by definition halved the work for an attack. In this specific analysis, I need only consider those settings of key bits (in this case, bits of p and q) that correspond to observed behavior for an interval of the spectogram. This means that I can potentially crack the key in time almost linear in the size of the key, rather than completely exponential.

        The work on timing attacks and power attacks uses very similar sorts of information, and the anlysis used here will likely be similar also. This is why Shamir, who is certainly qualified to evaluate the work at this point, describes it as "proof of concept": it would be surprising if the observed information fails to extend to a practical attack. It's just that in science, you publish when you have anything interesting to report, so that folks know you got there first.

        • Re:No no (Re:No) (Score:2, Interesting)

          by Jim Starx ( 752545 )
          I think your parent hit it on the nose. You're never going to "hear" individual bits. The computer processes at speeds that are fucking orders higher then the best sample rates known to man. The atoms of air just can't be excited that fast. They can't hold that type of information. Shamir is qualified, but that doesn't mean everything he works on is going to be a cryptographic holy grail. This is really interesting stuff, and there's certainly big potential here, but lets not kid ourselves about the p
    • Is this similar to the noise heard when using an onboard sound card? On my laptop when plugged in to the mains, a distint hiss/buzz/rumble comes out the line-out jack. It changes when moving the mouse or accessing the hard disk, or when the CPU is under load.

      It seems that this is a more reliable method for finding a key than using a microphone, but, of course, it does require physical access to the computer.
      • Is it a Dell?

        At work we need to by the Dell power adapter with two prongs (no ground) or in a pinch clip the ground off of a standard one. We do audio video display in court rooms, noone wants to here the whining of a computer.

        It is only on dells we have noticed this which is why I ask.
    • It's kinda freaky!!!

      Don't you mean 'phreaky'?
  • I have a 2.4ghz Pentium 4b on an Asus P4B266 motherboard. Hearing my capacitors buzzing and sinking when the processor is under full load is comforting because I can tell if there is some kind of process hogging my load. Unfortunately, it is extremely annoying after a while, but I don't want to spend the money to get a new motherboard. :(
    • I usually get this on my own setup a P4b-266 w/1.7(oc'd to 1874), but only after a reboot; and only do you hear it on re-init's prior to loading windows(pick a flavor) or BSD. Not when the machine is running.

      I'm thinking that it's the little critters getting just abit too hot, I found that increasing the airflow and cooling everything down by a couple of degrees seems to make the noise go away.'s in the which case...the house is more then cool enough and you don't have to worry ab
      • No kidding. I can't believe I bought such an incredibly slow mother board for my new processor. I bought it because it was by Asus and it was only $45.

        I don't think the capacitor problem has to do with heat. I just think that the speed of the processor is too great for such an old mobo. The recommended range for the board is 1.4ghz-2.4ghz. I'm on the high end of that spectrum unfortunately. I hear the caps going all the time when there is any load on the processor. I don't know if you would be abl
        • It would be worth something to try anyway, when I picked up the board two years ago it was pushing almost $300. And was top of the line. lol In your case it's abit slow for what you want. There are some good gigabyte boards out now that are around $100, this one here seems to be holding it's own even being OC'd. But I'm just going to wait later in the year to upgrade the rest of this system. No real point.

          If you do hear the caps going all the time, then there is a chance that the board may have sat fo
    • i've got the wonderful feature of sound effects from my box when performing just about any GUI operation you care to mention, i originally thought that it was a monitor issue, now you tell me my privacy is at risk because of it!

      time to fit more fans and drown out the noise.

      • BiggyP: "...time to fit more fans and drown out the noise."

        Read the article. Fans won't drown out the noise because signals are typically in the range above 10kHz, so the lower frequency sounds, like fans, can be filtered out.

  • by relyter ( 696205 ) on Saturday May 08, 2004 @12:13PM (#9093948)
    I've got so many fans running in my computer that you can't even hold a conversation in the same room, much less listen for capacitors
    • not so lucky (Score:4, Insightful)

      by hatchetman82 ( 719635 ) on Saturday May 08, 2004 @12:23PM (#9094004)
      "...For example, a high-quality analog equalizer can be used to attenuate strong low-frequency fan hums and background noise..."
      taken from the article.
      you'd need background noise in the same frequency area (dummy CPU ?)
      • Perhaps if I just piped in a simple singnal generating circut and filled the local area with white noise of about the same frequency of the northbridge?
        • Fourier analysis can detect signals below the noise floor. White noise would certainly make it really fucking hard. But not theoretically impossible. Instead, just buy a soundproof box for the computer, like the kind recording studio's used.
      • i don't know, the whooshing and other noises my fan makes are more like white noise - it certainly covers a much broader spectrum than a simple hum, and it's loud enough to be more than background noise

        of course, i don't know what i'm talking about, so take my comment for whatever you think it's worth
  • by foidulus ( 743482 ) on Saturday May 08, 2004 @12:14PM (#9093954)
    Wouldn't it just be easier to use money/women/men/donkeys to bribe the person to cough up a password?
    I guess you could always "bug" a place, but if you were significantly paranoid about security(to the point where someone would try to listen your key away from you) wouldn't you have a copper cage around your building?
  • by artlu ( 265391 ) <artlu AT artlu DOT net> on Saturday May 08, 2004 @12:14PM (#9093955) Homepage Journal
    The article does not deal with actually computing the encoding (Pe) and decoding functions (Pd) for q,n,d. Where q,n are unique primes. The only thing their interference spotted is the markings between computing each function for the signature, and this drastically varies based on the machine. They do have a Proof of Conept, but no quantifiable data.
    My $0.02.

    artlu []
  • Investigations are an important part of the justice system. Though the tenet is "innocent until proven guilty", it's only possible to prove someone guilty by means of an investigation.

    By encrypting your data, you are bringing unnecessary suspicion upon yourself. I wouldn't be surprised if the FBI's powers are enhanced to include surveillance of you and your data.
    • by LostCluster ( 625375 ) * on Saturday May 08, 2004 @12:32PM (#9094060)
      Even if the FBI/NSA can't manage to decode your data, the fact remains if they get to look at your HD via a warrent and they discover 20 GB of encrypted data rather than anything readable, they know you're hiding something from their view.

      That discovery encrypted data can still be used as evidence in justifying further warrants... while discovering 20 GB of Britney Spears music in readable form would most likely cause the investigation to give up on worrying about the contents of that hard drive.
      • So the logical thing to do is make the encrypted files play like MP3s of Britany or MC Hammer and it's perfectly safe.

        As long as you never accidentally press "Play" that is.
      • Even if the FBI/NSA can't manage to decode your data, the fact remains if they get to look at your HD via a warrent and they discover 20 GB of encrypted data rather than anything readable, they know you're hiding something from their view.

        That discovery encrypted data can still be used as evidence in justifying further warrants... while discovering 20 GB of Britney Spears music in readable form would most likely cause the investigation to give up on worrying about the contents of that hard drive.

        If you r
      • ... the fact remains if they get to look at your HD via a warrent and they discover 20 GB of encrypted data...

        One of the nice features of crypto on Linux is that you preseed the partition with random data dd-ed from /dev/random. Then when you start creating a filesystem you change around the bits on the disk, but it still looks like random data.

        I wonder if there's a way to see whether or not the disk has has a crypto filesystem on it, or if it was just being prepared for that purpose?
    • Small nit-pick: presumed innocent until proven guilty.
    • by Roman_(ajvvs) ( 722885 ) on Saturday May 08, 2004 @12:47PM (#9094134) Journal
      By encrypting your data, you are bringing unnecessary suspicion upon yourself

      Encryption inhibits surveillance by ANYONE. That the government falls under the category of anyone is secondary to most encryption desires and uses.

      If someone was attempting avoidence/prevention of potential government investigation, then the act of encrypting wouldn't make it more or less likely. They make use of encryption because they have some information they don't want the government to know. It's not because they use encryption but due to any relevant knowledge they have, that a person should ellicit investigation by their government. And then knowledge pertaining only to those things that governments should worry about (murder, fraud, and other criminal acts).

      So by encrypting the code on my laptop as a security precaution, you're saying I bring unnecessary suspicion upon myself? Noone but my company and its business competitors has an interest in the trade secrets I manage and create during the course of my business. Therefore I use encryption as a means of self-defense. I inhibit investigation by those not authorized by me or my company. The act of investigation could very well be illegal. I would not give my government blanket access to my trade secrets, when I have no control over what they do with them. They should have no interest in them. in fact, by wanting to enhance surveillance of those things which they declare to not have an interest in and would normally have no involvement in is suspicious in itself. Encryption is a tool and is about as dangerous as a screwdriver.

    • With the introduction of IP telephony, one of the first things people are going to want is encryption or people could just sniff packets and record your phone conversation. So telecomm equipment vendors like Avaya, Alcatel, Nortel, etc must allow for wire taps (as per the FCC).
  • Does anyone... (Score:5, Interesting)

    by centralizati0n ( 714381 ) <tommy.york@gmail . c om> on Saturday May 08, 2004 @12:17PM (#9093969) Homepage Journal
    Does anyone know the range of how far you can be away from the computer to hear the sounds? The proof-of-concept website just seemed to be "look, here are pictures of computer operations... in sound! Yay!" without enlightening us on any details.
    • Really, it depends on what equipment is being used to pick up the sounds.

      Think about WiFi. Your standard access point and and laptop card will work for about 300 feet. However, somebody 1000 feet away could interact with that network using a simple pringles can attenna.

      The same theory basically can be applied to sound, the more directional microphone and the better it is at filtering unwanted sound, the better the signal-to-noise ratio will get. So, putting walls and other background noises into the probl
      • You could put your computer into a soundproof box. They're actually pretty easy to find, used alot in music studio's to kill fan noise and such. Of course, access could still be gained by breaking into the box or anything like that. But as access goes a sound source is alot easyer to control then a WiFi network.
    • by Anonymous Coward
      Did you even read the article? This comes from before the pictures of the sounds, even, and I quote:

      The recordings below were made under nearly ideal conditions: the microphone was placed 20cm from the recorded computer, the PC case was opened and noisy fans were disconnected (where applicable). Comparable results where achieved under more realistic conditions (i.e., the subject computer is intact and placed 1m to 2m from the microphone) using more expensive audio equipment.

      • Well, maybe, just maybe, I wanted info about theories of how far you could actually be away from the laptop to retrieve the sounds, or the type of room the laptop was placed in that would provide the most opportune moment for capturing the sounds. Maybe I wanted to know how degraded the results could be in order to get the info about the processing. Maybe you should just crawl back into your cave, AC.
  • by DrLZRDMN ( 728996 ) on Saturday May 08, 2004 @12:18PM (#9093978)
    the wont be able to hear it if you've got one of these []
  • by belmolis ( 702863 ) <billposer AT alum DOT mit DOT edu> on Saturday May 08, 2004 @12:22PM (#9093996) Homepage

    Twenty years ago at Bell Labs one of the speech machines (an SEL with homebrew audio i/o) had output to loudspeakers that went through unshielded speaker wires that ran past the CPU, so if you weren't playing anything back the speakers played back CPU noise. We could tell what stage a compilation was at by the noise that came over the speakers.

    • by LiquidCoooled ( 634315 ) on Saturday May 08, 2004 @12:37PM (#9094082) Homepage Journal
      I actually still get that.

      If i turn my speakers wayyyyyyyyyyyyy up and start working, I can here the data being moved around. Scares the crap out of me when something plays a sample, but fun all the same.

      Its happened on my 2 most recent boards, and I just put it down to the integrated sound cards vs the Sound blasters I used to use.

      • I used to have that problem. I have an extension jack for the speaker out and mic at the front of my case.

        One day when I had the case open and was moving stuff around, I noticed it made noise whenever I bumped the cable for said jacks. Once removed, the noise went away.... probably not the same thing in your case, but gotta love unshielded cables.
      • I get that on laptops a lot, especially this one Windows laptop. I get various feedback in the sound system based on what's happening (harddrive access vs CPU)
      • In my case it started with mobo's with integrated audio. Even on low volume I can hear it clearly.

        Strange thing is that high cpu usage actually dampens the noise, so my solution was to run a distributed computing client (THINK, in my case, but others will do as well) to keep the cpu busy. Works perfectly, and I even forgot I had the problem until I read this post.

        I do think it's pretty lame that so many on-board audio chips have this problem.

    • The Vectrex video game system runs an unshielded audio cable right past the tube and you can hear the system pulling the photons around - as it's a vector scan system, it produces an extremely wide variety of noise on the speaker.
    • My old Atari ST would emit different background hiss via the TV modulator output depending on the CPU load.
    • I had a 6502 based computer (not the Apple II). When it went into reset mode after an assembly screw up, I could hear the different sound coming from the CPU. I had exactly 3 seconds to press the NMI button or the machine would do a hard reset. The NMI button was under the keyboard so it was a quickdraw to turn it over and grab a pen to press it. I eventually rewired it on top of the keyboard because if I missed the 3 seconds window I had to reload 20 minutes of tape into the machine. It was an Oric 1 in 19
  • Aha! (Score:5, Funny)

    by dupper ( 470576 ) * <> on Saturday May 08, 2004 @12:22PM (#9093998) Journal
    Now I have an excuse to play loud music at work: security!
  • As much as this technology is a risk and therefore a potential threat, unless you are of the reaslly paranoid (which would mean this interests you considerably) there are far easier ways of attacking a computer.

    This attack came to show how to attack the key, which is why it interests these folks, I suppose, but it would be much easier to use TEMPEST if you get access to actually install some tool to hear && (record || trasmit) the audio.

    I would suggest TEMPEST would also be more reliable, but some
  • by Anonymous Coward
    What a ridiculous load of bunk. You cannot possibly use audio frequencies to infer any meaningful information about what's happening on a processor running at 1,000 MHz or higher clock speeds. Repetitive sampling techniques would be necessary, and I don't think anyone's key-generation algorithm is going to sit in a tight loop, doing the exact calculations over and over for the weeks of wall-clock time it would take to sample any actual key data by acoustical means.

    All this article "proves" is that a CPU'
  • Patenting. (Score:3, Interesting)

    by Zangief ( 461457 ) on Saturday May 08, 2004 @12:36PM (#9094076) Homepage Journal
    If you go to the site of the DPA attack [],Cryptographic Research, you can see that they have already have patents on Systems to protect against these kind of attacks. So it's not like they have developed anything (I don't know if they have) but you can already pay them to get protection from this kind of attack! yay!
  • by suso ( 153703 ) on Saturday May 08, 2004 @12:41PM (#9094101) Homepage Journal
    This sounds kinda like that crack that the college student found in 1995 dealing with the speed of the CPU determining what random numbers the host would pick. A good reason not to keep your CPU info in the HINFO line of a DNS zone file.
  • by idiot900 ( 166952 ) * on Saturday May 08, 2004 @12:42PM (#9094111)
    Even at a 96 kHz sampling rate, the maximum frequency that can be sampled is 44 kHz. How could one hope to extract a certain few bits from a recording when the CPU's instruction throughput is many times that? Most of the information that would need to be examined wouldn't make it onto the recording. Correct me if I'm wrong, but it seems Nyquist leaves this idea dead in the water.
    • by Insount ( 11174 ) * <> on Saturday May 08, 2004 @12:54PM (#9094168) Homepage
      > How could one hope to extract a certain few bits from a recording when
      > the CPU's instruction throughput is many times that?

      The few bits you're trying to extract may have an observable influence on global statistics, especially when you can affect the value of some other bits. See for example Boneh and Brumley's timing attack on OpenSSL [].
    • by Doctor Wonky ( 105398 ) on Saturday May 08, 2004 @01:08PM (#9094231)
      What they did was, create tight loops performing the same operation over and over. And found that different operations tend to result in different sorts of noise on the power supply, resulting in different sounds from the capacitors.

      Remember though with their 96,000 Hz sampling rate, a 1 Ghz CPU performs over 10,000 instructions per sample.

      Air does not vibrate fast enough, and there are no microphones with frequency response high enough to let you look at individual operations.

      So I guess, if you knew the characteristics well enough, you could record the sound of the capacitors and say 'Hey, this guy is running GnuPG' on it. I don't see a concievable way to figure out the keys and this article doesn't suggest one.
    • I don't think the idea is to extract certain bits. This hasn't moved out of the concept phase. Even when it does it probably won't go extrodinarily far in terms of practical applications. The point is just that information can be gathered. It may not be bits, but it can tell you how much work the computer is doing, when it's doing it, and as the examples show there is a possibility of determining what type of operations are being performed. Your not going to "hear" they key or anything like that. But
  • by bhmit1 ( 2270 ) on Saturday May 08, 2004 @12:44PM (#9094121) Homepage
    ...but all I heard was "Dave, what are you doing Dave?"
    Hmm, maybe I should put away the screwdriver.
  • Obviously this attack requires physical access to the machine. And with physical access to the machine there are easier ways to extract keys. So this is really only relevant if you want to protect against somebody with physical access, that wouldn't perform a simpler attack, which could involve disassembling the machine. I think some chipcards you would use to protect keys is a case, where you might worry about such attacks. But how much noise does a chipcard produce, I think with those it would make more s
    • "So this is really only relevant if you want to protect against somebody with physical access"

      While it's true this requires you to have had physical access to the machine at some point, it's the time and level of access that are the issue.

      For instance while it is fairly rare to get the level of physical access you need to employ other attacks on a bank terminal, it's a breeze to get the level of access you need to do this.

      You don't need to login, you don't need to open the case/bypass locks on it/damage
  • Eavesdropping is an old technique, it's interesting that it's being touted as something new. Okay so the context is a bit different but not all that different. Is even the context all that new? It may be new to the authors (and readers?) but it's probably not new to those folks that employ creative techniques to snoop. A microphone works great to "log" keystrokes. The delays between key presses can be used to create a pattern that in turn can define exactly what's been typed. Passive listening devices
  • by Anonymous Coward
    When I listen to my computer, it just tells me "Snap, crackle, burn!"
  • by JanusFury ( 452699 ) <kevin,gadd&gmail,com> on Saturday May 08, 2004 @12:58PM (#9094190) Homepage Journal
    It tells me to troll Slashdot, and buy Kenny G albums.

    I'm starting to think it doesn't have my best interests at heart...
  • Anyone who uses software powersaving/CPU cooling in windows or linux has heard this noise. Programs like CPUIdle [] et all put the processor into an HLT state and cool it significantly (12+ degrees here). I run the thing to cool my massive laptop [] which would get quite hot during renders and things, what with it's 10K RAID etc.. I hear this hum in a lot of electronics that have no moving parts (routers, computers, etc..), and have always wondered about it. In a chat on IRC we chalked it up to electric freque
    • by 0x0d0a ( 568518 ) on Saturday May 08, 2004 @01:34PM (#9094348) Journal
      The most common thing I've found to induce audible noise (I use a SB Live, and can easily hear this with even cheap speakers) is to demute the sound card inputs that aren't connected to anything -- like CD audio and whatnot -- and then start moving my PS/2 mouse, which generates a fairly slow sequence of signals, producing a definite buzz. Video redraw also can do this -- dragging windows works well as well, and what's on the screen (oddly enough, lots of white areas seems to cause more of a buzz) has an impact.

      It's really amazing how dirty a computer power supply is -- I also picked up a headphone preamp that fits inside a 5.25" drive bay, and can optionally run off the computer power supply. If it's running off the power supply, I get a *very* noisy signal that is affected by things like hard drive access.
  • by Effugas ( 2378 ) on Saturday May 08, 2004 @01:06PM (#9094220) Homepage
    Shamir, once again pointing out something absolutely brilliant and (in retrospect) totally obvious, did forget to include something rather important in his announcement:

    The particular pattern of CPU operations executed while an RSA private key is executed varies depending on that RSA private key. Given a rough estimate of the pattern of CPU operations executed, the set of possible RSA private keys is greatly reduced. So it becomes much, much easier -- possibly trivial, particularly if you have a chosen plaintext scenario -- to extract a private key from an otherwise secure system. Consider an e-voting machine with an audio system for handicapped access -- with nothing but a very sensitive microphone in the booth, you might be able to determine the private key used to sign votes (and thus gain the capability to spoof votes elsewhere).

    And of course, this would be a very, very successful attack against an RSA private key embedded within a trusted computing environment. Processors -- even those encased in epoxy -- still need power, and variable amounts depending on what they're doing. The brilliance here is that rather than needing some very expensive analog energy drain measurement equipment, you just need a sound card. It's a side channel attack for the masses.

    Very very cool work. Wow.

  • by Hans Lehmann ( 571625 ) on Saturday May 08, 2004 @01:07PM (#9094227)
    Other than fans & hard drives, I don't think I've ever heard noise from any machine I've ever worked on, though back in the old days we would hold an AM radio next to the computer, which would give very distinct noise patterns as the CPU went about its business.

    If you really want to do some acoustic evesdropping, listen to the keyboard. It's got a much larger signal to begin with (from across the room, instead of having to paste your ear to the computer case.) Since there are always slight mechanical differences between keys on any given keyboard, I would think that the sound spectrum would also be slightly different. Being able to always listen in on the same user would also help, since most people are somewhat consistent regarding which finger they use on which key. (Evesdropping on people who were smart enough to take a touch-typing class in high school is also a big plus.)

    Assuming you could discern between the acoustic fingerprint of 100 different keys, then it's just a matter of figuring out which sound goes with which key. It's a simple substitution cypher, which are almost trivial to break.

    Sneak your cell phone into your boss's office, set it to silent mode and plug in a headset so that you can set it to auto-answer when a call comes in. Then, while your boss is busy typing dirty notes to his mistress, you call your cell phone, start recording it, and presto, you've got a keylogger without ever having touch his computer or the software on it. Then, at your next performance review, you convince him to give you a hefty raise.


  • I've heard of Tempest emanations/ Van Ecks for eavesdropping. Supposedly the technique can grab keystrokes from remote machies. Just google for "tempest eavesdropping" if you want info on this.
  • I remember Adi Shamir talked about this at his talk at Carnegie Mellon in March. He gave a brief description and said that it was in the works. So many people doubted it.

  • Interesting... (Score:5, Interesting)

    by boola-boola ( 586978 ) on Saturday May 08, 2004 @01:35PM (#9094360)
    It is interesting to note that Adi Shamir (one of the co-authors) is one of the three people who came up with RSA-encryption []

    R = Ron Rivest
    S = Adi Shamir
    A = Len Adleman

  • by Zizkus ( 658125 ) on Saturday May 08, 2004 @02:02PM (#9094498)
    Having worked in telecommunications as well as consumer electronics and computing, I've played a lot :) One of the more interesting things for fun was to poke around with a induction amplifier, you know, the "hound" in the fox and hound tone generator/ handheld probe that the phone guys use for tracing copper thru a building. It is pretty sensitive and I've found many fun sounds by waving it around in various analog and digital equipment, it kinda gives a unique viewpoint. Used in different locations in a PC it picks up various interesting sounds that are very different according to what the system is doing, and where you are probing, memory, chipset, io/chips, cpu etc. Never found it very good for troubleshooting PC's, but lots of fun! Also, I think the sounds you can hear around running electronics is partly caused by sympathetic viberation induced in the air molecules by high frequency energy changes happening, especially on the buses where there are long runs exposed, as well as perhaps by the caps, (?), could it be the aluminum in the caps is reacting to the energy field?, most of the round tall caps you see on a board are used on low frequency mainly power filtering applications.
  • by LoadWB ( 592248 ) on Saturday May 08, 2004 @02:39PM (#9094734) Journal
    I recall reading rumors of a blind fella who could play MunchMan on the TI-99/4 just by listening to the sounds in the background of the game.

    While my experience is no where near that in-depth, I do remember that the computer made distinct sounds when performing certain tasks, such as reading GROM, initializing, running BASIC programs (I recall that some statements also have distinct sounds as well.)

    Since then I have been able to detect certain sounds from my machines which indicate normal operations; to some extent I think we all do, just as we do with cars to "know" that something isn't right. And it's been pretty consistent through all of my computers: Commodore 64, 128D, Atari 800XL, various Amigas (amazing things heard by holding your ear to the A500 power supply,) many desktop PCs and notebooks. Even some console systems generate sounds under operation (an old NES on my shelf with a bad filter cap is good for this.)

    I'm curious to know what correlations between design type, grounding, processor architecture, and other factors exist for this. Might be worth investigating like this chap did, should I find the time to do so.
  • How can you differentiate between computations , when the CPU is at 100% utilization all the time? :)
  • Well... (Score:2, Informative)

    by marcansoft ( 727665 )
    Actually sound from computers can come from many places, and sometimes you han make out a hell of a lot of info about what a user is doing.

    Typical CPU HLT execution either by the O/S (linux and w2k or so i thought... w2k didn't do it too good when I tried it) or by an external program (on ring 0) e.g CpuIDLE will cause several things, from what I've experienced:

    Variable fan speed: Typical cheap comes-with-case power supplies regulate +5V whiwh surprise! gets a greater power draw when CPU is busy. Result,
  • Time to start designing tin foil hats... ...for your computer.

    Man, that is real geek stuff.
  • The processor is operating at several gigahertz; in other words, the electrical signals are changing thousands of millions of cycles a second.

    A microphone will pick up frequencies from just shy of DC, to a few tens of kilohertz. Let's be really generous and suppose that the microphone can follow a vibration of 100kHz. A 2GHz signal will have changed 20 000 times in the same amount of time the microphone's diaphragm could have moved back and forth once. Need I say more?

    It's like the myth about hard d
  • FAQ (Score:5, Informative)

    by Insount ( 11174 ) * <> on Saturday May 08, 2004 @05:37PM (#9095804) Homepage
    (I'm a co-author of the presentation.)

    The web page [] was extended to include a FAQ discussing the issues brought up here.
  • >brain pop

    it's like Van Eck, only scarier.

    makes me wonder though...
    Seems to open the door for a true broadcastable computer virus.
    I mean, if you can can get sound out, and it means something, why not put instruction-filled sound in, overriding currently queued instructions...

    I've finally figured out how Cobra Commander is able to appear on ALL televisions at once before revealing his plans to take over the world!
  • When I was about 6, my dad had a work laptop that he brought home. It had a grey-scale screen, dual 3.5" floppies, 4 (I think) MB of RAM, and no hard drive.

    The only things he had for it was WordPerfect and "Where in the World is Carmen Sandiago?" Based on the sound of the spinning drive, I could decipher which of the multiple choice answers was correct to move to the next stage while the current stage was loading. After a while, I started plugging my ears while a stage was loading so the game didn't suc

I THINK MAN INVENTED THE CAR by instinct. -- Jack Handley, The New Mexican, 1988.