# Researchers extract RSA encryption key from sound of working CPU **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [December 19, 2013, 3:46am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692 "2013-12-19T03:46:46Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 3:46am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/1 "2013-12-19T03:46:46Z")
This blows my mind. :eek: [RSA Key Extraction via Low-Bandwidth Acoustic Cryptanalysis](http://www.cs.tau.ac.il/~tromer/acoustic/) > [@](#): > > Here, we describe a new acoustic cryptanalysis key extraction attack, applicable to GnuPG’s current implementation of RSA. The attack can extract full 4096-bit RSA decryption keys from laptop computers (of various models), within an hour, using the sound generated by the computer during the decryption of some chosen ciphertexts. We experimentally demonstrate that such attacks can be carried out, using either a plain mobile phone placed next to the computer, or a more sensitive microphone placed 4 meters away. Then there’s this: > [@](#): > > We demonstrated another low-bandwidth channel: the electric potential of the laptop’s chassis. In many computers this “ground” potential fluctuates (even when connected to a grounded power supply) and leaks the requisite signal. This can be measured in several ways, for example: > > ``` > Magic-touch attack: the attacker measures the chassis potential by merely touching the laptop chassis with his hand, while surreptitiously measuring his own body potential relative to the room's ground potential. (This attack is especially effective in hot weather, since sweaty fingers offer a lower electric resistance.) > Far-end-of-cable attack: the victim plugs in some innocuous-looking VGA or Ethernet cable into his laptop. The attacker measures the shield electric potential on the far side of the cable (out of sight, in some cabinet or server room). > > ``` ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [December 19, 2013, 3:49am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/2 "2013-12-19T03:49:07Z")
But what about the Vorpel Protocol? ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 3:54am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/3 "2013-12-19T03:54:10Z")
Okay, this is weird. I didn’t know what you meant by “Vorpel Protocol” so I googled it. The first hit was this thread. This was within 3 minutes of your post; and it’s labeled “20 hours ago - 2 posts - ‎2 authors”. [https://www.google.com/search?client=ubuntu&channel=fs&q=Vorpel+Protocol&ie=utf-8&oe=utf-8#channel=fs&nfpr=1&q=Vorpel+Protocol&safe=off](https://www.google.com/search?client=ubuntu&channel=fs&q=Vorpel+Protocol&ie=utf-8&oe=utf-8#channel=fs&nfpr=1&q=Vorpel+Protocol&safe=off) ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [December 19, 2013, 4:15am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/4 "2013-12-19T04:15:08Z")
You didn’t know what I meant? Well, that makes two of us. I was making a gentle joke about my mystification over your post, which I didn’t understand in the least. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 4:20am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/5 "2013-12-19T04:20:48Z")
What my post means is that researchers have show that it’s possible to obtain a decryption key by analyzing the high frequency sounds given off by a CPU. So, for example, if you are sitting in a Starbucks and you enter the password to read an encrypted super-secret email, someone nearby with a microphone and the right equipment can steal your password simply by recording the sounds of your computer. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 4:21am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/6 "2013-12-19T04:21:52Z")
But I’m still trying to figure out Google’s time travel trick. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [December 19, 2013, 4:52am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/7 "2013-12-19T04:52:47Z")
> [@davidm](#): > > What my post means is that researchers have show that it’s possible to obtain a decryption key by analyzing the high frequency sounds given off by a CPU. > > So, for example, if you are sitting in a Starbucks and you enter the password to read an encrypted super-secret email, someone nearby with a microphone and the right equipment can steal your password simply by recording the sounds of your computer. Not really. You need to have your computer process a particular file that the crypto software needs in order to obtain the key. ---
**Author:** ![The\_Second\_Stone](https://avatars.discourse-cdn.com/v4/letter/t/bbe5ce/32.png) [@The\_Second\_Stone](https://boards.straightdope.com/u/The_Second_Stone)\ **Post date:** [December 19, 2013, 4:59am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/8 "2013-12-19T04:59:42Z")
I’m still trying to figure out the trick where one local mom whitens her teeth so much all the local dentists hate her. I think it is safe to say that if the NSA wants inside your computer, they will get inside your computer. ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [December 19, 2013, 10:18am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/9 "2013-12-19T10:18:28Z")
> [@davidm](#): > > What my post means is that researchers have show that it’s possible to obtain a decryption key by analyzing the high frequency sounds given off by a CPU. > > So, for example, if you are sitting in a Starbucks and you enter the password to read an encrypted super-secret email, someone nearby with a microphone and the right equipment can steal your password simply by recording the sounds of your computer. Hm what would happen with someone tapping their fingernails on the laptop case… I have an annoying habit of tapping on my case while I am waiting for stuff. No idea why or how I picked up the damned habit but I try to control it. But if it would confound the eavesdroppers I could stop trying to suppress it.😛 ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 1:13pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/10 "2013-12-19T13:13:21Z")
> [@beowulff](#): > > Not really. > You need to have your computer process a particular file that the crypto software needs in order to obtain the key. True. I was trying to keep it non-technical. The point is that these techniques can be used to access encrypted data. Of course they’d still need physical access to the actual file, although it strikes me that similar techniques may render that unnecessary. ---
**Author:** ![The\_Niply\_Elder](https://avatars.discourse-cdn.com/v4/letter/t/8e8cbc/32.png) [@The\_Niply\_Elder](https://boards.straightdope.com/u/The_Niply_Elder)\ **Post date:** [December 19, 2013, 1:48pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/11 "2013-12-19T13:48:12Z")
But in the real world wouldn’t acoustic noise and RF noise render these attack ineffective? It seems to me that gathering this data in a laboratory setting is one thing, but pulling it off in a public place is another. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [December 19, 2013, 2:05pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/12 "2013-12-19T14:05:24Z")
What this means is that, until the courts rule otherwise, the government(or anybody else with the proper equipment) can get confidential information from your supposedly encrypted files without a warrant. ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [December 19, 2013, 3:30pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/13 "2013-12-19T15:30:34Z")
> [@Czarcasm](#): > > What this means is that, until the courts rule otherwise, the government(or anybody else with the proper equipment) can get confidential information from your supposedly encrypted files without a warrant. But I don’t have any confidential information sniffle ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 4:06pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/14 "2013-12-19T16:06:21Z")
There have been ways to do this type of thing for a while now, based on electromagnetic emissions from the computer. What blows my mind about this is that they’re using the physical vibrations of the CPU. It never would have crossed my mind that this was even remotely possible. It’s conceivable that moving electrons around and flipping transistor states could cause some physical motion - we are manipulating matter after all - but the idea that those vibrations contain some useable information is something I would have dismissed out of hand. ---
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [December 19, 2013, 4:33pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/15 "2013-12-19T16:33:09Z")
You’ve got a few mistakes **davidm**. The sound is not from the chip but from the voltage regulation circuit. See [Q2 here](http://www.cs.tau.ac.il/~tromer/acoustic/) Also, they are not accessing encrypted data, they are recovering the target’s RSA private key. They use the target’s public key to encrypt several text files known to the attacker and email them to the target. When the target opens the email GnuPG decrypts the text using the private key. By knowing what data is being decrypted and analyzing the sound generated they can recover the private key. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [December 19, 2013, 5:06pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/16 "2013-12-19T17:06:39Z")
> [@aruvqan](#): > > But I don’t have any confidential information sniffle Yeah, well I have a lot of HUGE secrets that I don’t want anybody finding out about. Okay, well, I have couple of REALLY BIG secrets. Well, one that’s kinda secret, to me anyway. I got nothin’. ☹ ---
**Author:** ![Rysto](https://avatars.discourse-cdn.com/v4/letter/r/ecccb3/32.png) [@Rysto](https://boards.straightdope.com/u/Rysto)\ **Post date:** [December 19, 2013, 6:41pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/17 "2013-12-19T18:41:18Z")
> [@davidm](#): > > It’s conceivable that moving electrons around and flipping transistor states could cause some physical motion - we are manipulating matter after all - but the idea that those vibrations contain some useable information is something I would have dismissed out of hand. What’s far more likely is that depending on the key, the processor does more or less work on the chosen plaintext, which triggers the system’s fan to go faster or slower. Edit: Never mind, kferr actually read the synopsis and found the actual culprit. ---
**Author:** ![davidm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/davidm/32/225_2.png) [@davidm](https://boards.straightdope.com/u/davidm)\ **Post date:** [December 19, 2013, 11:14pm UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/18 "2013-12-19T23:14:32Z")
> [@kferr](#): > > You’ve got a few mistakes **davidm**. The sound is not from the chip but from the voltage regulation circuit. See [Q2 here](http://www.cs.tau.ac.il/~tromer/acoustic/) > > Also, they are not accessing encrypted data, they are recovering the target’s RSA private key. They use the target’s public key to encrypt several text files known to the attacker and email them to the target. When the target opens the email GnuPG decrypts the text using the private key. By knowing what data is being decrypted and analyzing the sound generated they can recover the private key. I took “computer” to mean “CPU” but fair enough, you got me on that. Regarding your other point, my thread title makes it very clear that I was discussing the extraction of keys. ---
**Author:** ![Digital\_is\_the\_new\_Analog](https://avatars.discourse-cdn.com/v4/letter/d/a88e4f/32.png) [@Digital\_is\_the\_new\_Analog](https://boards.straightdope.com/u/Digital_is_the_new_Analog)\ **Post date:** [December 20, 2013, 3:57am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/19 "2013-12-20T03:57:12Z")
I remember a story a few years ago about duplicating the image on a CRT, based on the sounds the original made when displaying it. Pretty cool technology, along the same lines. (ha! same lines!) ---
**Author:** ![njtt](https://avatars.discourse-cdn.com/v4/letter/n/ecd19e/32.png) [@njtt](https://boards.straightdope.com/u/njtt)\ **Post date:** [December 20, 2013, 4:57am UTC](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692/20 "2013-12-20T04:57:40Z")
> [@davidm](#): > > But I’m still trying to figure out Google’s time travel trick. It is not time travel, it is simply predictive text. Should we really be surprised that Google, with its huge server farms and access to all human knowledge and everyone’s internet activity, can predict what **Chefguy** is going to post much sooner and much more completely and accurately than, say, a little phone could do? 😉 What I can’t figure out is what they need the [killer robots](http://www.benzinga.com/news/13/12/4158019/did-google-acquire-boston-dynamics-to-manufacture-killer-robots) for. [Next page](https://boards.straightdope.com/t/researchers-extract-rsa-encryption-key-from-sound-of-working-cpu/676692.md?page=2)