Think of it as lots of itty bitty low power radio transmitters and receivers.
It isn't like that at all. Try using a capacitor plate as an antenna. Doesn't work too well, does it?
This technique uses electric fields to couple signals without using wires. That's all. There is no antenna, there is no carrier wave, there is no modulation scheme. It's a capacitor. And we've used capacitors to couple oscillating signals for nearly a hundred years. It's called a "high pass filter."
The only thing that makes this story interesting whatsoever is the fact that they can produce so many of these things in such close proximity to each other and align them so perfectly.
Say you could place a chip intervening between a severed spinal cord. Instead of having to physically attach all those millions of nerve endings, you could have the chip do it by proximity, and carry the signals on past the gap.
Nerve cells already work this way. There is no physical contact between the axons and dendrites. They come very, very close to each other. A potential wave (electric pulse) travels from the nerve soma down the axon, where it causes a huge number of neurotransmitter-filled vacuoles to migrate to the cell membrane. These vacuoles open and release the neurotransmitters into the synaptic gap, where they are carried, purely by diffusion, to the receptor of the adjacent dendrite. There they bind to the dendrite surface and initiate a new, distinct electric pulse in the receiving cell.
In other words, nerve cells work quite a bit like this "capacitive coupling" technology, except instead of using electric fields they use chemical agents to transmit signals.
Your nervous system is partially electrical in nature, but signals are propogated between cells by chemicals, not electric pulses!
Of all the articles I've ever read on Slashdot, this one takes the cake as far as demonstrating the utter ignorance about electromagnetism by the majority of people here.
I admit it's a tough field (hehe) to really get a grasp on, but seriously... Don't comment with false authority on things you barely understand.
So all the communications inside the computer will be implemented with radio waves?
No. A wave is a combination of an electric and a magnetic field. This capacitive coupling relies exclusively on the electric field. Yes, Maxwell's equations state that a fluctuating electric field induces a magnetic field, but the field is small.
Theoretically, a very small amount of radiation could escape in a radial direction from the gap between the capacitor plates. But this is true of any type of capacitor.
The chip is not using "radio waves" to communicate. It is using an electric field.
By the way, it is very simple to spy on signals in wires, because the current flowing in a wire produces a magnetic field. This can be detected without tapping the wire.
In other words, I can already spy on your computer if I have sophisticated enough equipment.
Does anybody know of any good explanations of how or why capacitive coupling works?
Similar charges repel. Thus, if you put two plates very close to each other, and charge one of them up, the resulting electric field will repel the charges in the other plate.
It's exactly how any other capacitor works. I don't see what's so confusing about this.
What is that property of photons where they some how join then split them
That's parametric downconversion
and what ever happens to the one will happen to the other, even if it is on the other side of the universe?
That's entanglement, although you're description isn't exactly accurate. Both photons collapse from a superposition into the same quantum state.
I don't see why people aren't using this for a mode of communication or to replace wires.
What is the point? There's no particular advantage to it, and it requires fairly advanced equipment. If you're thinking "faster than light" communication, think again. It's not possible, even with entanglement.
It's actually much easier to listen to signals if they travel through wires. With a wire, there is an actual current flowing over a significant distance, which means the magnetic field of that current will be detectable over a fairly big area.
It is true that capacitive coupling produces a very small "displacement current," which isn't a real current but is just a way of describing the effect of electromagnetic induction, but the resulting magnetic field will only exist over a very small region.
if the bandwidth is that high, and a bank of these things is supposed to work together, how are they going to prevent crosstalk?
Crosstalk is a magnetic effect between wires. There are no wires here, and hence no significant current, and hence no magnetic field. (Yes, for you EM geeks, there is "displacement current", in other words, magnetic induction due to the fluctuating electric field, but it's going to be miniscule.)
The only issue would be field spread at the edges of the capacitive region, but that could be minimized with careful placement.
Whistleblower? That's moronic. Whistleblowing is when you bust a power abuser like Ken Lay who pillages billions of dollars. This is not whistleblowing.
What right does this person have to dictate what his boss should do? If he doesn't feel his boss is performing his job correctly, he should report it to the higher-ups, which he did. The higher-ups didn't care. This should have been a big fucking hint. Perhaps his boss can do his job and play Solitaire at the same time. Maybe that's why he ended up as Boss.
Here on Slashdot, many people post and read articles from work. This is claimed as "Okay," because we're getting our jobs done regardless, right? But when it comes to somebody in a position of power, suddenly playing a mindless cardgame is such a horrible violation that a sysadmin must "blow the whistle?" I call bullshit.
This idiot overstepped his boundaries. What makes it worse is that he was a government employee and demonstrated an intent to use his position as system administrator to spy on other government employees. This is completely unacceptable, and it was entirely appropriate to fire his dipshit ass.
He might not be blameless, but he is not responsible. I'm glad you brought this up, because it's exactly my point.
Kids will be running around screaming, yelling, victimizing small animals, and in every case, the child is blameless.
Correct. Because he doesn't know any better, and it is my responsiblity to control his behavior. It sounds like you're the one who'd make a bad parent, since you seem to believe that children will magically form a set of ethics all by themselves. If my kid goes out, gets drunk, and runs somebody over, that's my fault. I wasn't in control of the situation.
But this isn't the point. The point is, when you accepted a job to maintain and secure a set of servers, you accepted responsibility for what happens to those servers, in return for compensation. Sure, it probably wouldn't be right to sanction or fire somebody just because a system got hacked, but they sure as hell better take responsibility because that's what they're being paid for.
Sheesh. Here on Slashdot, we rant about Windows bozos who allow trojan spam software to execute on their systems -- we want to hold these people responsible for their actions because malware affects everybody negatively. But I guess when it comes to you, you can't wait to pass the buck, can you?
Seriously. Kid does something wrong, obviously something he wasn't supposed to do, and if it crashed the server, it wa something very malicious. And the admin's to blame?
Yes. If you can't take the heat, don't do the job. It's called "accountability."
This guy, apparently, isn't willing to take responsiblity for getting owned by a child.
Don't see the problem really. Why would anybody give read access to device nodes for regular users?
If regular users can't access the device anyway, why bother encrypting it?
Encryption protects you from people who have physical access to the machine. People like coworkers who rifle through your stuff after you go home. Or the feds. Whoever.
My point is, if you are counting on encryption to protect your data from snoops, you better have an encrypted swap partition, otherwise your encryption password might end up, clear as a blue-sky day, on your swap partition.
It's not that hard, using strings, to look for things that might be likely passwords and just try them all.
Never mind the people who, you know, actually create products.
Without products, and people who market and sell those products, and people who support the consumers of those products, sysadmining becomes a wank-fest.
As an engineer I'm tempted to say "Engineers are the ones keeping the wheels turning," but I know that isn't true; without marketing and sales staff, my job would be pointless.
I think sysadmin appreciation day is a great idea. Now, how about engineering appreciation day, too?
I think this post deserves at least one "Insightful" mod. It's easy to recommend your friends and family use Linux, but the situation is quite a bit different in an environment where it is your job to support the system.
The difference is, with Windows, you spend most of your time supporting the computer. With Linux, you spend most of your time supporting the user. Linux isn't a magic bullet which will melt away all your support problems! The user must be knowledgeable, or else you'll just waste even more time than Windows was already wasting.
You have to be able to observe the state to recieve information and you have to be able to transmit the state to send information. Someone can observe the state in the middle and then quickly retransmit a copy. The original signal is corrupted just as QM predicts but the copy is in it's place.
What you've just described is precisely what quantum cryptography makes impossible. You assume you can "restransmit a copy." However, it is impossible to clone a quantum state without destroying it.
Hence, as soon as an eavesdropper taps in, he is immediately detected, at which point both ends of the conversation simply stop talking.
Sure, you can DOS a QC channel, but you can do that to ANY channel. The beauty of QC is that it is physically impossible to eavesdrop on the channel in an undetectable way, and this is guaranteed by some very fundamental laws of physics.
I, for one, would flame someone who suggested changing the semantics of pipes. Well-defined interfaces are the heart of reliable software.
I fully agree, but I'd hesitate to call pipes a "well defined" interface. POSIX attempts to standardize semantics, but there are still mismatches between Unix-like platforms.
The changes this fellow was proposing (don't remember the details, too long ago) were on the same order as the typical differences in semantics between platforms. In other words, I think there's a region of reasonable wiggle-room but the majority of kernel developers seem intolerant of even these small divergences from the status quo.
In addition, people have a tendency to reject new features even if they do not conflict with traditional features. For example, look at the discussions on the kernel list back when futexes were being discussed.
Incidentally, I came up with a nearly identical idea about a year earlier, but I called it "user wait queues." Threads could block on a queue and be woken by other threads. However, my mechanism for waiting on a queue involved a new system call, whereas futex waits are implemented (I think) by using an ioctl to bind the futex to a fd, and then select()'ing on the fd. I did not submit my idea to the kernel people precisely because I felt it would be rejected as "not Unix enough." Usings fds and select() is traditional, but a syscall would be more efficient, IMHO.
It's that sort of conservatism that I'm talking about, not the perfectly reasonable effort to preserve interfaces.
We are all in this make something "better," aren't we? Or is this whole OSS thing just one big echo chamber?
No, the entire OSS community is not an echo chamber, but the kernel development community is. I've seen flamefests caused by some poor soul suggesting very minor changes to, for example, the semantics of pipes. Unix isn't just written in stone, it's laminated and stored in an evacuated nuclear-blastproof case 500 meters underground.
Is the Linux/Unix community so "steeped in tradition" (also known as stubborness, obstinance, intolerance, and narrow-mindedness) that it willfully clings to an outdated, inferior way of doing things?
Again, it is not the community as a whole which is stuck, but the kernel people. I was simply pointing out the truth, not trying to say it's a good thing. Although I think it is wise to be suspicious of radical new ideas until they have proven themselves, I think that many times ideas are rejected for purely dogmatic reasons, and that really restricts innovation.
A few chars from your password will, of course, turn up in many files purely by coincidence.
But there is a much higher probability that your password exists in its entirety on the swap partition.
I forgot that grepping a binary file only produces "File matches" by default. An AC appears to have already corrected my post. First run 'strings' on the swap partition, and run grep on the output of strings.
I'm not guaranteeing you'll find your password in there, but I'm willing to bet that at least a few people will.
use a loop device. We have had encrypted filesystems for several years.
Everyone seems to like this method. But do you also encrypt your swap partition? If not, then whenever the system swaps, unencrypted data gets stored somewhere on the swap partition.
Here's something that might terrify you: run grep on your swap partition and give it a few characters from your password. You needn't list the entire password. Scary, eh? (This won't work for everyone, but it might for you.)
Remember, if you're using loopback with crypto, you're just pissing in the wind unless you encrypt your swap, too.
Solid, universal support for ACLs, and while we're at it, let's fix the whole user/group namespace mess Unix has with it.
While I think this is a very good idea, the end result would certainly not be Unix. Like it or not, Unix is steeped in tradition, and part of that tradition is that divergence from the tradition is unacceptable.
Unix without traditional UID/GID just isn't Unix anymore.
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It isn't like that at all. Try using a capacitor plate as an antenna. Doesn't work too well, does it?
This technique uses electric fields to couple signals without using wires. That's all. There is no antenna, there is no carrier wave, there is no modulation scheme. It's a capacitor. And we've used capacitors to couple oscillating signals for nearly a hundred years. It's called a "high pass filter."
The only thing that makes this story interesting whatsoever is the fact that they can produce so many of these things in such close proximity to each other and align them so perfectly.
Nerve cells already work this way. There is no physical contact between the axons and dendrites. They come very, very close to each other. A potential wave (electric pulse) travels from the nerve soma down the axon, where it causes a huge number of neurotransmitter-filled vacuoles to migrate to the cell membrane. These vacuoles open and release the neurotransmitters into the synaptic gap, where they are carried, purely by diffusion, to the receptor of the adjacent dendrite. There they bind to the dendrite surface and initiate a new, distinct electric pulse in the receiving cell.
In other words, nerve cells work quite a bit like this "capacitive coupling" technology, except instead of using electric fields they use chemical agents to transmit signals.
Your nervous system is partially electrical in nature, but signals are propogated between cells by chemicals, not electric pulses!
Far less jammable than a system using wires (i.e. antennas!)
There's a reason we put out computers inside grounded metal cases, you know.
Hi, Roland!
I admit it's a tough field (hehe) to really get a grasp on, but seriously... Don't comment with false authority on things you barely understand.
No. A wave is a combination of an electric and a magnetic field. This capacitive coupling relies exclusively on the electric field. Yes, Maxwell's equations state that a fluctuating electric field induces a magnetic field, but the field is small.
Theoretically, a very small amount of radiation could escape in a radial direction from the gap between the capacitor plates. But this is true of any type of capacitor.
The chip is not using "radio waves" to communicate. It is using an electric field.
By the way, it is very simple to spy on signals in wires, because the current flowing in a wire produces a magnetic field. This can be detected without tapping the wire.
In other words, I can already spy on your computer if I have sophisticated enough equipment.
Similar charges repel. Thus, if you put two plates very close to each other, and charge one of them up, the resulting electric field will repel the charges in the other plate.
It's exactly how any other capacitor works. I don't see what's so confusing about this.
That's parametric downconversion
and what ever happens to the one will happen to the other, even if it is on the other side of the universe?
That's entanglement, although you're description isn't exactly accurate. Both photons collapse from a superposition into the same quantum state.
I don't see why people aren't using this for a mode of communication or to replace wires.
What is the point? There's no particular advantage to it, and it requires fairly advanced equipment. If you're thinking "faster than light" communication, think again. It's not possible, even with entanglement.
It's actually much easier to listen to signals if they travel through wires. With a wire, there is an actual current flowing over a significant distance, which means the magnetic field of that current will be detectable over a fairly big area. It is true that capacitive coupling produces a very small "displacement current," which isn't a real current but is just a way of describing the effect of electromagnetic induction, but the resulting magnetic field will only exist over a very small region.
Crosstalk is a magnetic effect between wires. There are no wires here, and hence no significant current, and hence no magnetic field. (Yes, for you EM geeks, there is "displacement current", in other words, magnetic induction due to the fluctuating electric field, but it's going to be miniscule.)
The only issue would be field spread at the edges of the capacitive region, but that could be minimized with careful placement.
What right does this person have to dictate what his boss should do? If he doesn't feel his boss is performing his job correctly, he should report it to the higher-ups, which he did. The higher-ups didn't care. This should have been a big fucking hint. Perhaps his boss can do his job and play Solitaire at the same time. Maybe that's why he ended up as Boss.
Here on Slashdot, many people post and read articles from work. This is claimed as "Okay," because we're getting our jobs done regardless, right? But when it comes to somebody in a position of power, suddenly playing a mindless cardgame is such a horrible violation that a sysadmin must "blow the whistle?" I call bullshit.
This idiot overstepped his boundaries. What makes it worse is that he was a government employee and demonstrated an intent to use his position as system administrator to spy on other government employees. This is completely unacceptable, and it was entirely appropriate to fire his dipshit ass.
He might not be blameless, but he is not responsible. I'm glad you brought this up, because it's exactly my point.
Kids will be running around screaming, yelling, victimizing small animals, and in every case, the child is blameless.
Correct. Because he doesn't know any better, and it is my responsiblity to control his behavior. It sounds like you're the one who'd make a bad parent, since you seem to believe that children will magically form a set of ethics all by themselves. If my kid goes out, gets drunk, and runs somebody over, that's my fault. I wasn't in control of the situation.
But this isn't the point. The point is, when you accepted a job to maintain and secure a set of servers, you accepted responsibility for what happens to those servers, in return for compensation. Sure, it probably wouldn't be right to sanction or fire somebody just because a system got hacked, but they sure as hell better take responsibility because that's what they're being paid for.
Sheesh. Here on Slashdot, we rant about Windows bozos who allow trojan spam software to execute on their systems -- we want to hold these people responsible for their actions because malware affects everybody negatively. But I guess when it comes to you, you can't wait to pass the buck, can you?
Yes. If you can't take the heat, don't do the job. It's called "accountability."
This guy, apparently, isn't willing to take responsiblity for getting owned by a child.
If regular users can't access the device anyway, why bother encrypting it?
Encryption protects you from people who have physical access to the machine. People like coworkers who rifle through your stuff after you go home. Or the feds. Whoever.
My point is, if you are counting on encryption to protect your data from snoops, you better have an encrypted swap partition, otherwise your encryption password might end up, clear as a blue-sky day, on your swap partition.
It's not that hard, using strings, to look for things that might be likely passwords and just try them all.
If you were able to crash his server, it sounds like he wasn't doing his job very well. Maybe he's the one who should be banned.
I think they'd get less abuse if they deflated their egos a little bit, and tried to join the rest of us here in "social reality."
Without products, and people who market and sell those products, and people who support the consumers of those products, sysadmining becomes a wank-fest.
As an engineer I'm tempted to say "Engineers are the ones keeping the wheels turning," but I know that isn't true; without marketing and sales staff, my job would be pointless.
I think sysadmin appreciation day is a great idea. Now, how about engineering appreciation day, too?
The difference is, with Windows, you spend most of your time supporting the computer. With Linux, you spend most of your time supporting the user. Linux isn't a magic bullet which will melt away all your support problems! The user must be knowledgeable, or else you'll just waste even more time than Windows was already wasting.
What you've just described is precisely what quantum cryptography makes impossible. You assume you can "restransmit a copy." However, it is impossible to clone a quantum state without destroying it.
Hence, as soon as an eavesdropper taps in, he is immediately detected, at which point both ends of the conversation simply stop talking.
Sure, you can DOS a QC channel, but you can do that to ANY channel. The beauty of QC is that it is physically impossible to eavesdrop on the channel in an undetectable way, and this is guaranteed by some very fundamental laws of physics.
I fully agree, but I'd hesitate to call pipes a "well defined" interface. POSIX attempts to standardize semantics, but there are still mismatches between Unix-like platforms.
The changes this fellow was proposing (don't remember the details, too long ago) were on the same order as the typical differences in semantics between platforms. In other words, I think there's a region of reasonable wiggle-room but the majority of kernel developers seem intolerant of even these small divergences from the status quo.
In addition, people have a tendency to reject new features even if they do not conflict with traditional features. For example, look at the discussions on the kernel list back when futexes were being discussed.
Incidentally, I came up with a nearly identical idea about a year earlier, but I called it "user wait queues." Threads could block on a queue and be woken by other threads. However, my mechanism for waiting on a queue involved a new system call, whereas futex waits are implemented (I think) by using an ioctl to bind the futex to a fd, and then select()'ing on the fd. I did not submit my idea to the kernel people precisely because I felt it would be rejected as "not Unix enough." Usings fds and select() is traditional, but a syscall would be more efficient, IMHO.
It's that sort of conservatism that I'm talking about, not the perfectly reasonable effort to preserve interfaces.
No, the entire OSS community is not an echo chamber, but the kernel development community is. I've seen flamefests caused by some poor soul suggesting very minor changes to, for example, the semantics of pipes. Unix isn't just written in stone, it's laminated and stored in an evacuated nuclear-blastproof case 500 meters underground.
Is the Linux/Unix community so "steeped in tradition" (also known as stubborness, obstinance, intolerance, and narrow-mindedness) that it willfully clings to an outdated, inferior way of doing things?
Again, it is not the community as a whole which is stuck, but the kernel people. I was simply pointing out the truth, not trying to say it's a good thing. Although I think it is wise to be suspicious of radical new ideas until they have proven themselves, I think that many times ideas are rejected for purely dogmatic reasons, and that really restricts innovation.
A few chars from your password will, of course, turn up in many files purely by coincidence.
But there is a much higher probability that your password exists in its entirety on the swap partition.
I forgot that grepping a binary file only produces "File matches" by default. An AC appears to have already corrected my post. First run 'strings' on the swap partition, and run grep on the output of strings.
I'm not guaranteeing you'll find your password in there, but I'm willing to bet that at least a few people will.
Everyone seems to like this method. But do you also encrypt your swap partition? If not, then whenever the system swaps, unencrypted data gets stored somewhere on the swap partition.
Here's something that might terrify you: run grep on your swap partition and give it a few characters from your password. You needn't list the entire password. Scary, eh? (This won't work for everyone, but it might for you.)
Remember, if you're using loopback with crypto, you're just pissing in the wind unless you encrypt your swap, too.
While I think this is a very good idea, the end result would certainly not be Unix. Like it or not, Unix is steeped in tradition, and part of that tradition is that divergence from the tradition is unacceptable.
Unix without traditional UID/GID just isn't Unix anymore.
No, he really does mean 1934.