I find it unbelievable that there's already a 7-qubit quantum computer, even if it is NMR. But what would impress me more is if one or two of the existing algorithms for various problems were implemented on it successfully. Obviously it doesn't take much skill to prime factor the numbers between 0 and 127. But it would still be a quite remarkable advance.
On a side note, the only thing quantum encryption and quantum computers have in common is the use of the word "quantum". The similarities between the two are the same as the similarities between electrical engineering and mechanical engineering. Try http://www.qubit.org for basic tutorials on quantum computers, etc.
Why is Dupont incorporated in Delaware? It certainly isn't because Delaware is rich in petroleum.
Well, DuPont made all of its money initially from gunpowder. Not oil. Sure, it had that whole Conoco thing going for a while, but that's the past. On a side note, DuPont has always been a leader in, say, nylons. That Carruthers guy was pretty useful. And DuPont makes Kevlar (bullet-proof vests), Teflon (Kevlar-piercing bullets), and myriad other useful synthetics. So remember, the next time you think of DuPont, think of that magic word that people here in Delaware associate with DuPont: Downsize!
Well, I for one won't be too surprised if the DVD edition doesn't show up until after Episode 3. But then, I could be mistaken, as I doubt they would abandon the transfer to DVD completely.
Of course, I rather enjoy having a DVD player, the quality is better and I find it more convenient than trying to hook up a VCR through my tv card. Plus, there are plenty of other movies to rent while waiting for Lucas to come to his senses.
I do tend to agree with Jon in so much as there is an obvious effect of corporations on the freedoms available to that third sacred right, "pursuit of happiness".
And I do agree that the injunctions presented regarding DeCSS are extreme, but on the other hand I see reason behind the banning of Napster where others seem to see little. The colleges that are moving to ban Napster are not doing so to infringe upon the rights of the students. Nor are they doing so to support the music industries. They are doing so to keep their own costs down. Quite honestly, they cannot be infringing upon the rights of these students, as the students' access to a college's bandwidth is not a right, at least, not at the college I currently attend. It is a privilege. There should, in fact, be little argument over this, as most universities have "Responsible Computing" policies that specifically state that the use of the university's bandwith is a privilege that can be revoked by the university for any reason.
I myself am a big fan of the concept of private property, i.e. when I buy something, it is mine; I have the right to do whatever I want with it such that in doing so I don't infringe upon the rights of others. Thus, I analogize decrypting a DVD to cutting all the pages out of a book and making origami with it. But I'm also the type of person who analogizes hacking (Whoops, misnomer, I must mean cracking. (Whoops, misnomer, I mean criminal entry)) into a computer system with breaking into my house. Thus, Kevin Mitnick is really nothing more than an overglorified cat burglar, albeit a clever one. This is also where a great deal of problems arise. As Jon has pointed out, the results of these situations (the DeCSS injunction, etc.) most affect abstract ideas which sometimes can be analogized, and sometimes can't. And, often, the analogies that can be found are contradictory. I see Mitnick as a cat burglar; the government sees him as the most dangerous computer user to be let free. Perhaps we're both right, perhaps neither is correct. It's always been a perspective issue; only recently has the political situation strayed to the degree that we concentrate on our economy as there are no real threats to us politically. The Cold War is over. There are less than half a dozen (I think) Communist nations left, and those that are still here pose no threat to the security of the United States (China's a toss-up, I'll admit that). The Internet has arisen and become an incredible source of information, and has undoubtedly enhanced the lives of everyone using it. Life is quite different than it was 30 years ago, and I would venture to say it's better.
Jon himself has pointed out that we are being limited by corporations. I would like to emphasize that the corporations that his focus is on are entertainment industries. The threat is not to our lives, but to our enjoyment of them. The fact that this is the case has me particularly pleased. We are at a point where we can complain about how few choices we have to spend leisurely. A hundred and fifty years ago, this wouldn't have been the case.
As many people have pointed out, the key to this realization of the American Dream not becoming the American Nightmare is the dissemination of information. The American public are not a techno-cognoscenti. The information discussed on Slashdot would necessarily need to be spread out to the rest of the people, through whatever means necessary, if this course of action were to be taken. And that won't happen until a serious analysis of the situation happens, and until enough people are willing to do so. Anyone can post their opinion anonymously or pseudo-anonymously on the Internet, myself obviously included. But how many people are willing to publically support the ideas they profess on the Internet? Obviously not everyone. Anonymity is an important part of our lives. Unfortunately, as long as our anonymity remains a high priority, these problems will not just go away.
I don't ask that anyone agrees with me; to do so would be your choice. However, I do ask that whomever reads this message has the courtesy to think about what I've said before responding. Courtesies are not necessary, but they are pleasant.
First: what this means with respect to quantum encryption is that if someone's eavesdropping, you'll know they're eavesdropping because the error rates of your communication with the other person will skyrocket, and you'll know something's up.
Second, what you've described is the man-in-the-middle approach to defeating encryption. Charles Bennett, the researcher who proposed the current quantum encryption algorithm, states that you have to have two communication lines: one that is quantum, and one that is public, and you cannot have a man-in-the-middle on the public line. Why would this change anything? Well, you use the public line to exchange information in the data initiation sequence. You say "I sent this data and it was like this", and the other person notes it and corrects their data translation, and vice versa. Then, if someone intercepts it from then on, error rates go up. Otherwise, the person will have been there BEFORE they initiated contact. This means all the data they get will make NO SENSE WHATSOEVER, and they'll abandon the data line before they use it. But Bennett knew a man-in-the-middle in the public channel would screw this up, that's why he said avoid it. If that didn't clear anything up, lemme know.
First, I'd like to point out that quantum computation and quantum encryption are two almost completely separate concepts. Quantum encryption is based on the fact that quantum states cannot be measured without altering. The most common example is the polarization of a photon, but it will work for any quantum state, so long as there exist, effectively, two unique states that can transmit the data.
Quantum computation, however, is much more complex and much more interesting. Quantum computers are based on the concept of quantum entanglement, the ability of a quantum state to exist in a superposition of all of its mutually exclusive states: It's a 1 and a 0. However, this is not as easy to use as one might think. While it's true that if you have n quantum logic gates you have the ability to input 2^n data values simultaneously (as opposed to only 1 piece of data if you have n digital logic gates), this is not going to be the end of classical computing for a few reasons. First, quantum computers have to be perfectly reversible. That means for every output there's an input and vice versa. And there has to be no way of knowing the initial states of the data. You don't process data, you process probabilities in a quantum computer; if you know exactly what any one value is throughout the computation, you can find out all of the values: the superposition ends and you're stuck with a useless chunk of machinery. This means YOU CAN ONLY GET ONE RESULT FROM ANY QUANTUM COMPUTATION, THE END RESULT. You can't see what the data in the middle is or the computer becomes useless. (Landauer's principle makes heat loss data loss. When your processor gets hot, it's losing data. If the same thing happened to a quantum computer, it wouldn't be quantum anymore.) Decoherence is what happens when you randomly lose data to the environment by design, not by choice, and the superposition ends. This is bad for Q.C. Oh, and quantum computers can only do *some* things faster, like prime factorization and discrete logarithms. Not multiplication or addition. Plus, the circuits that would do basic arithmetic would be bigger and slower than what you've currently got.
So what does this all mean? It means that quantum computers are going to provide some advantages (real quick big number factorization), and some disadvantages (that whole RSA standard). The most realistic initial use of quantum computers will be as add-ons to existing super-computers to resolve certain types of NP-Complete headaches that regular math can't simplify yet. At best they will someday be an add-on to your PC; but they will never replace the digital computer.
- HyLander
If you want more info, check out http://www.qubit.org, it's got some decent tutorials, or email me at hylander42@hotmail.com.
Here's the deal: It's a two part key-transmission protocol. The quantum channel is assumed to be actively eavesdropped (i.e. eavesdroppers are, without a doubt, changing something, thanks to that German guy). The regular channel can/is being passively eavesdropped (i.e. eavesdroppers aren't changing anything, just listening). The important thing is that they share only a few (not all) of the correctly receiveded bits so they can compare whether or not the error rates were correct. It's the error rate that matters, they can afford to sacrifice the values of a few bits. It doesn't matter if Eve can catch the photons; as long as Eve doesn't know the exact polarizations that Alice uses prior to Alice's transmission, it's guaranteed that Eve will screw a few up in her eavesdropping, and thus Bob will get wrong values, compare them with Alice, decide they were being eavesdropped, and they will cease communications on that channel.
I've already responded to this type of post, but I believe that it was too far in a thread to be noticed.
First, Bennett requires that Alice and Bob have access to a medium that cannot be actively (man-in-the-middle) monitored, such as a phone call. Any eavesdropping of a quantum channel is, thanks to Heisenberg, active. But with a passive-eavesdropping-only public channel, Alice and Bob can tell each other which photons were received and which weren't. Thus, if Eve becomes the "man" in the middle, she changes the polarisations of all of the photons she sends out according to that Heisenberg fellow.
Secondly, Alice and Bob base the security of their system on error rates of photon transfers. They would notice an unusually high error rate, and avoid further communications from that line. And because all they did was send random one-time-pad information, Eve has gained absolutely nothing of use from all of her work.
Quantum cryptography essentially provides effective key distribution for two people who have a passive-eavesdropping-only communications medium, so all the arguments about a man in the middle become moot.
Well, you aren't the first to bring this up. In his paper "Quantum Cryptography: Public Key Distribution And Coin Tossing", Bennett himself acknowledges that one of the requirements is that the two parties have access to a medium that requires no active eavesdropping, such as a phone call. In this situation, the man in the middle would be quickly realized.
Sure, there won't be many of these built for a while, and sure, only governments might be able to afford them. But remember, it isn't just a few people with PGP that rely on RSA. Banks do. Government agencies do. Other governments do. I personally don't want some revolutionary nut in a third-world country stealing a quantum comp. and raiding my bank account. I'm funny that way.
To the Anonymous Coward who suggested quantum encryption:
Oh boy, there's some fun: first, you have to build your own communication medium, because phone lines and satellites are out. It has to be strong, it has to be extremely accurate, and it has to be completely isolated. Oh, and you'll need to make many different versions. And they all have to be hard-wired, as you can't do this sort of thing over radio waves. I'll explain why at the end. Second, you have to know what the error rates of the particles you're sending actually are. Counting photons is a tedious job. Third, you have to find someone else with the same setup you've got.
So you finally got your quantum encryption set up. Now what? Well, here's where it gets funny: quantum "encryption" is as effective if you are using 256-bit RSA encryption or if you are using the secret code from the ring you found in your Cracker Jack box. Why? Encryption is based on the concept that you don't want anyone to whom you don't give permission to see your data. All quantum encryption does is change the medium so that one of those pesky laws of quantum physics, Heisenberg's cute "uncertainty principle", keeps other people from looking at your stuff when it's in transmission without you knowing. You will know someone's watching because the error rates have risen. Oh, and to keep this medium working, it has to be as isolated from natural interference as possible. So, what happens when you know that someone's reading your stuff? You have to change channels, so to speak, and use a different connection, or wait until that eavesdropper gets off your communication line. Sounds annoying, doesn't it? Well, it is, as well as financially unfeasible for, say, an entire country.
Don't understate the power of the quantum logic gate. The quantum computer isn't merely moving around the processors so all of the jumps happen in the same cycle. A quantum computer uses a fundamentally different logic gate. In essence, the 1 and the 0 are both registered at the same time because what's being registered is not the particle, but the probability of where the particle might go. The probabilities are what are manipulated by the hardware, and where the electrons actually go determines the answer. This is as simple as it gets. However, I know that this probably doesn't make much sense to a lot of people. (It only makes some sense to me because I had to write a report on quant. computation&cryptography and neg. probability.) My advice to anyone who is not extremely well-versed in both computer science and quantum mechanics (there are like a dozen of them on the planet) is to find a book on the subject. I'd recommend G.L. Milburn's "The Feynman Processor" (he's one of those dozen).
Slashdot Mirror
I find it unbelievable that there's already a 7-qubit quantum computer, even if it is NMR. But what would impress me more is if one or two of the existing algorithms for various problems were implemented on it successfully. Obviously it doesn't take much skill to prime factor the numbers between 0 and 127. But it would still be a quite remarkable advance.
On a side note, the only thing quantum encryption and quantum computers have in common is the use of the word "quantum". The similarities between the two are the same as the similarities between electrical engineering and mechanical engineering. Try http://www.qubit.org for basic tutorials on quantum computers, etc.
Why is Dupont incorporated in Delaware? It certainly isn't because Delaware is rich in petroleum.
Well, DuPont made all of its money initially from gunpowder. Not oil. Sure, it had that whole Conoco thing going for a while, but that's the past. On a side note, DuPont has always been a leader in, say, nylons. That Carruthers guy was pretty useful. And DuPont makes Kevlar (bullet-proof vests), Teflon (Kevlar-piercing bullets), and myriad other useful synthetics. So remember, the next time you think of DuPont, think of that magic word that people here in Delaware associate with DuPont: Downsize!
Well, I for one won't be too surprised if the DVD edition doesn't show up until after Episode 3. But then, I could be mistaken, as I doubt they would abandon the transfer to DVD completely.
Of course, I rather enjoy having a DVD player, the quality is better and I find it more convenient than trying to hook up a VCR through my tv card. Plus, there are plenty of other movies to rent while waiting for Lucas to come to his senses.
I do tend to agree with Jon in so much as there is an obvious effect of corporations on the freedoms available to that third sacred right, "pursuit of happiness".
And I do agree that the injunctions presented regarding DeCSS are extreme, but on the other hand I see reason behind the banning of Napster where others seem to see little. The colleges that are moving to ban Napster are not doing so to infringe upon the rights of the students. Nor are they doing so to support the music industries. They are doing so to keep their own costs down. Quite honestly, they cannot be infringing upon the rights of these students, as the students' access to a college's bandwidth is not a right, at least, not at the college I currently attend. It is a privilege. There should, in fact, be little argument over this, as most universities have "Responsible Computing" policies that specifically state that the use of the university's bandwith is a privilege that can be revoked by the university for any reason.
I myself am a big fan of the concept of private property, i.e. when I buy something, it is mine; I have the right to do whatever I want with it such that in doing so I don't infringe upon the rights of others. Thus, I analogize decrypting a DVD to cutting all the pages out of a book and making origami with it. But I'm also the type of person who analogizes hacking (Whoops, misnomer, I must mean cracking. (Whoops, misnomer, I mean criminal entry)) into a computer system with breaking into my house. Thus, Kevin Mitnick is really nothing more than an overglorified cat burglar, albeit a clever one. This is also where a great deal of problems arise. As Jon has pointed out, the results of these situations (the DeCSS injunction, etc.) most affect abstract ideas which sometimes can be analogized, and sometimes can't. And, often, the analogies that can be found are contradictory. I see Mitnick as a cat burglar; the government sees him as the most dangerous computer user to be let free. Perhaps we're both right, perhaps neither is correct. It's always been a perspective issue; only recently has the political situation strayed to the degree that we concentrate on our economy as there are no real threats to us politically. The Cold War is over. There are less than half a dozen (I think) Communist nations left, and those that are still here pose no threat to the security of the United States (China's a toss-up, I'll admit that). The Internet has arisen and become an incredible source of information, and has undoubtedly enhanced the lives of everyone using it. Life is quite different than it was 30 years ago, and I would venture to say it's better.
Jon himself has pointed out that we are being limited by corporations. I would like to emphasize that the corporations that his focus is on are entertainment industries. The threat is not to our lives, but to our enjoyment of them. The fact that this is the case has me particularly pleased. We are at a point where we can complain about how few choices we have to spend leisurely. A hundred and fifty years ago, this wouldn't have been the case.
As many people have pointed out, the key to this realization of the American Dream not becoming the American Nightmare is the dissemination of information. The American public are not a techno-cognoscenti. The information discussed on Slashdot would necessarily need to be spread out to the rest of the people, through whatever means necessary, if this course of action were to be taken. And that won't happen until a serious analysis of the situation happens, and until enough people are willing to do so. Anyone can post their opinion anonymously or pseudo-anonymously on the Internet, myself obviously included. But how many people are willing to publically support the ideas they profess on the Internet? Obviously not everyone. Anonymity is an important part of our lives. Unfortunately, as long as our anonymity remains a high priority, these problems will not just go away.
I don't ask that anyone agrees with me; to do so would be your choice. However, I do ask that whomever reads this message has the courtesy to think about what I've said before responding. Courtesies are not necessary, but they are pleasant.
First: what this means with respect to quantum encryption is that if someone's eavesdropping, you'll know they're eavesdropping because the error rates of your communication with the other person will skyrocket, and you'll know something's up.
Second, what you've described is the man-in-the-middle approach to defeating encryption. Charles Bennett, the researcher who proposed the current quantum encryption algorithm, states that you have to have two communication lines: one that is quantum, and one that is public, and you cannot have a man-in-the-middle on the public line. Why would this change anything? Well, you use the public line to exchange information in the data initiation sequence. You say "I sent this data and it was like this", and the other person notes it and corrects their data translation, and vice versa. Then, if someone intercepts it from then on, error rates go up. Otherwise, the person will have been there BEFORE they initiated contact. This means all the data they get will make NO SENSE WHATSOEVER, and they'll abandon the data line before they use it. But Bennett knew a man-in-the-middle in the public channel would screw this up, that's why he said avoid it. If that didn't clear anything up, lemme know.
First, I'd like to point out that quantum computation and quantum encryption are two almost completely separate concepts. Quantum encryption is based on the fact that quantum states cannot be measured without altering. The most common example is the polarization of a photon, but it will work for any quantum state, so long as there exist, effectively, two unique states that can transmit the data.
Quantum computation, however, is much more complex and much more interesting. Quantum computers are based on the concept of quantum entanglement, the ability of a quantum state to exist in a superposition of all of its mutually exclusive states: It's a 1 and a 0. However, this is not as easy to use as one might think. While it's true that if you have n quantum logic gates you have the ability to input 2^n data values simultaneously (as opposed to only 1 piece of data if you have n digital logic gates), this is not going to be the end of classical computing for a few reasons. First, quantum computers have to be perfectly reversible. That means for every output there's an input and vice versa. And there has to be no way of knowing the initial states of the data. You don't process data, you process probabilities in a quantum computer; if you know exactly what any one value is throughout the computation, you can find out all of the values: the superposition ends and you're stuck with a useless chunk of machinery. This means YOU CAN ONLY GET ONE RESULT FROM ANY QUANTUM COMPUTATION, THE END RESULT. You can't see what the data in the middle is or the computer becomes useless. (Landauer's principle makes heat loss data loss. When your processor gets hot, it's losing data. If the same thing happened to a quantum computer, it wouldn't be quantum anymore.) Decoherence is what happens when you randomly lose data to the environment by design, not by choice, and the superposition ends. This is bad for Q.C. Oh, and quantum computers can only do *some* things faster, like prime factorization and discrete logarithms. Not multiplication or addition. Plus, the circuits that would do basic arithmetic would be bigger and slower than what you've currently got.
So what does this all mean? It means that quantum computers are going to provide some advantages (real quick big number factorization), and some disadvantages (that whole RSA standard). The most realistic initial use of quantum computers will be as add-ons to existing super-computers to resolve certain types of NP-Complete headaches that regular math can't simplify yet. At best they will someday be an add-on to your PC; but they will never replace the digital computer.
- HyLander
If you want more info, check out http://www.qubit.org, it's got some decent tutorials, or email me at hylander42@hotmail.com.
I don't know where in America you're from, but in Delaware and surrounding area it's pronounced lyn-ux.
Here's the deal: It's a two part key-transmission protocol. The quantum channel is assumed to be actively eavesdropped (i.e. eavesdroppers are, without a doubt, changing something, thanks to that German guy). The regular channel can/is being passively eavesdropped (i.e. eavesdroppers aren't changing anything, just listening). The important thing is that they share only a few (not all) of the correctly receiveded bits so they can compare whether or not the error rates were correct. It's the error rate that matters, they can afford to sacrifice the values of a few bits. It doesn't matter if Eve can catch the photons; as long as Eve doesn't know the exact polarizations that Alice uses prior to Alice's transmission, it's guaranteed that Eve will screw a few up in her eavesdropping, and thus Bob will get wrong values, compare them with Alice, decide they were being eavesdropped, and they will cease communications on that channel.
I've already responded to this type of post, but I believe that it was too far in a thread to be noticed.
First, Bennett requires that Alice and Bob have access to a medium that cannot be actively (man-in-the-middle) monitored, such as a phone call. Any eavesdropping of a quantum channel is, thanks to Heisenberg, active. But with a passive-eavesdropping-only public channel, Alice and Bob can tell each other which photons were received and which weren't. Thus, if Eve becomes the "man" in the middle, she changes the polarisations of all of the photons she sends out according to that Heisenberg fellow.
Secondly, Alice and Bob base the security of their system on error rates of photon transfers. They would notice an unusually high error rate, and avoid further communications from that line. And because all they did was send random one-time-pad information, Eve has gained absolutely nothing of use from all of her work.
Quantum cryptography essentially provides effective key distribution for two people who have a passive-eavesdropping-only communications medium, so all the arguments about a man in the middle become moot.
Well, you aren't the first to bring this up. In his paper "Quantum Cryptography: Public Key Distribution And Coin Tossing", Bennett himself acknowledges that one of the requirements is that the two parties have access to a medium that requires no active eavesdropping, such as a phone call. In this situation, the man in the middle would be quickly realized.
This is a two-parter:
First, to Sangui5:
Sure, there won't be many of these built for a while, and sure, only governments might be able to afford them. But remember, it isn't just a few people with PGP that rely on RSA. Banks do. Government agencies do. Other governments do. I personally don't want some revolutionary nut in a third-world country stealing a quantum comp. and raiding my bank account. I'm funny that way.
To the Anonymous Coward who suggested quantum encryption:
Oh boy, there's some fun: first, you have to build your own communication medium, because phone lines and satellites are out. It has to be strong, it has to be extremely accurate, and it has to be completely isolated. Oh, and you'll need to make many different versions. And they all have to be hard-wired, as you can't do this sort of thing over radio waves. I'll explain why at the end. Second, you have to know what the error rates of the particles you're sending actually are. Counting photons is a tedious job. Third, you have to find someone else with the same setup you've got.
So you finally got your quantum encryption set up. Now what? Well, here's where it gets funny: quantum "encryption" is as effective if you are using 256-bit RSA encryption or if you are using the secret code from the ring you found in your Cracker Jack box. Why? Encryption is based on the concept that you don't want anyone to whom you don't give permission to see your data. All quantum encryption does is change the medium so that one of those pesky laws of quantum physics, Heisenberg's cute "uncertainty principle", keeps other people from looking at your stuff when it's in transmission without you knowing. You will know someone's watching because the error rates have risen. Oh, and to keep this medium working, it has to be as isolated from natural interference as possible. So, what happens when you know that someone's reading your stuff? You have to change channels, so to speak, and use a different connection, or wait until that eavesdropper gets off your communication line. Sounds annoying, doesn't it? Well, it is, as well as financially unfeasible for, say, an entire country.
So, which is worse, the problem or the solution?
Mike
Don't understate the power of the quantum logic gate. The quantum computer isn't merely moving around the processors so all of the jumps happen in the same cycle. A quantum computer uses a fundamentally different logic gate. In essence, the 1 and the 0 are both registered at the same time because what's being registered is not the particle, but the probability of where the particle might go. The probabilities are what are manipulated by the hardware, and where the electrons actually go determines the answer. This is as simple as it gets. However, I know that this probably doesn't make much sense to a lot of people. (It only makes some sense to me because I had to write a report on quant. computation&cryptography and neg. probability.) My advice to anyone who is not extremely well-versed in both computer science and quantum mechanics (there are like a dozen of them on the planet) is to find a book on the subject. I'd recommend G.L. Milburn's "The Feynman Processor" (he's one of those dozen).
That's just my two cents though.
Mike