Quantum Cryptography Leaving the Lab 345
Theodore Logan writes "More than a year ago, MagiQ announced the world's first commercial quantum cryptography system (pdf), with ID Quantique following closely in their footsteps. Currently, the technology is limited to offering point-to-point connections up to a maximum distance of around 50 km, but this is likely to be greatly improved on in coming years. The systems available today are prohibitely expensive for the average Joe (MagiQ's are priced at more than $50,000 per unit), but one could envision a future in which they are built into the infrastructure by non-end user actors. Does this spell the end of the field of cryptography? Will systems like this ever become commonplace, or will they be reserved for sensitive financial transactions and military applications? What impact will quantum cryptography have on society? Good articles available from International Herald Tribune, EE Times and CNET."
It's worse than that, it's physics Jim (Score:5, Informative)
Since they make a point that they "Rely on the laws of physics", they're bound by them too (maths is far more forgiving
OTOH, it's the first generation of these devices, and perhaps IPv8 will somehow encode an encryption hierarchy (packets get encrypted sequentially in one direction, and decrypted on the way back, assuming the same route is taken, each node only needs to know the encryption to the next one worked ok to guarantee the encryption was ok. You'd still want to be in control of all the nodes along the way though...)
As for price - if they can solve the networking issue, that'll come down dramatically - it'll be onboard in the equivalent of the BIOS that we have in ten years time (when we all have fibre to the home. Possible optimistic
Simon
Re:It's worse than that, it's physics Jim (Score:5, Insightful)
With all due respect to the quantum guys, the traditional byte-crunching cryptography kind of has the market by the balls here.
Re:It's worse than that, it's physics Jim (Score:3, Insightful)
So wouldn't that make the secure transfer of the keys somewhat pointless?
Re:It's worse than that, it's physics Jim (Score:5, Insightful)
Realy Fast computers, including quantum computers, will brute force traditional (math based) crypto quicker then is possible now. Quantum cryptography is uncrackable unless you can figgure out a way to get around Heisenberg.
Re:It's worse than that, it's physics Jim (Score:3, Funny)
Re:depends on the potential payoffs (Score:3, Insightful)
Look at the FBI, NSA, CIA. (MI-5, GCHQ, MI-6) Just because the NSA can do all kinds of nasty computer based spying doesnt mean that the humans over at the CIA have nothing to do. And just because the NSA developes lots of nifty security things does not mean that the FBI no longer has to search for moles within
Re: Applications of quantum cryptography (Score:5, Insightful)
To the question asked by the artcle submitter: the answer is no (at least, not yet), because quantum cryptography (in its present form) may be useful for encrypting communications, but it is ineffective for encrypting stored data.
Re:It's worse than that, it's physics Jim (Score:5, Insightful)
Also, hop-by-hop security is not end-to-end security, so even if you do have all the routers in IPv8 using hop-by-hop encryption over petabit links, you'll still need end-to-end security.
So to answer the question in the post, unless you can afford a leased line with a single fiber, and that fiber is lossless enough to not need repeaters, this is only for things like financial institutions and spy networks.
Re:It's worse than that, it's physics Jim (Score:3, Interesting)
You now need to build software on top that shuts down/reroutes the link if its not happy that the route is secure.
For point to point applications (aggregated backbones etc) its great. For general networking
(espicially multiplexed / contention based paradigms we have now) its not s
Re:It's worse than that, it's physics Jim (Score:5, Informative)
What application? (Score:5, Insightful)
Now, if you could transfer a small symmetric key (well, at least on the order of bytes or kilobytes, not gigabytes), on the other hand...
Oh and one more thing - don't forget to have some kind of checksum on the OTP - if someone replaced the OTP with another OTP (standard man-in-the-middle attack) you wouldn't know... after all, it's only random data. The pads may no longer match, but who'd notice?
Kjella
Re:What application? (Score:3, Informative)
Re:It's worse than that, it's physics Jim (Score:3, Interesting)
Pure Mathematics is absolutely unforgiving. Applied Mathematics, such as Phys
Re:It's worse than that, it's physics Jim (Score:3, Informative)
Godel, alt
How easy is it to implement ? (Score:5, Interesting)
I've seen that regular geeks can build things such as quantum force microscopes in their own homes, how hard would it be for someone to build a quantum crypto system?
point to point (Score:2, Funny)
Re:point to point (Score:2, Interesting)
Kinda like putting your pr0nship on a holding pattern where no one else can touch it.
Re:point to point (Score:5, Funny)
I've heard you can use steganography to hide your data in .JPGs ;)
MagiQ server at bargain based prices (Score:5, Insightful)
Quantum Cryptography (Score:5, Insightful)
Re:Quantum Cryptography (Score:5, Insightful)
Re:Quantum Cryptography (Score:3, Funny)
Er well to do anything at all with a quantum line you need access to the fiber, at which point Denial of Service is most easily performed with a large axe.
Re:Quantum Cryptography (Score:3, Funny)
The definition of a man in the middle is that he can DOS your connection. There's no communication method that isn't vulnerable to disconnection. Even telepathy, as evidenced by Magneto's anti-Xavier helmet.
Re:Quantum Cryptography (Score:2, Funny)
As you saw it, you DOS'ed it.
(Quantum wave funcion collapse induced by observation. Play on words. Hey.. give me a break.. its Monday).
Re:Quantum Cryptography (Score:2)
Re:Quantum Cryptography (Score:5, Informative)
Wrong (Score:5, Interesting)
Reading datas alter them. So the man in the middle will be detected.
This is true for a passive attack, i.e., one were the attacker can only eavesdrop on a connection. However, in a man-in-the-middle attack, the attacker can also arbitrarily modify data. In particular you can have the following situation:
Here Alice thinks she is talking to Bob, but in fact she's talking to Eve, who decodes her packets, re-encodes them, and sends them to Bob. Unless Alice and Bob have some authentication mechanism (say, a shared secret key, or the other's public key), they have absolutely no way to tell that this is going on. The ability to detect eavesdropping on the quantum channel doesn't help at all, since Eve isn't eavesdropping - she's tunneling between two physically separate channels. Quantum cryptography does not differ in this respect from conventional cryptography: it's a basic fact of communication - how do you establish that the bits you are receiving come from the person/system from who you think they come?
Re:Wrong (Score:3, Informative)
Re:Quantum Cryptography (Score:2)
Re:Quantum Cryptography (Score:2, Informative)
Re:Quantum Cryptography (Score:3, Informative)
Re:Quantum Cryptography (Score:5, Informative)
The purpose of cryptography is to transmit information in such a way that access to it is restricted entirely to the intended recipient. Originally the security of a cryptotext depended on the secrecy of the entire encrypting and decrypting procedures; however, today we use ciphers for which the algorithm for encrypting and decrypting could be revealed to anybody without compromising the security of a particular cryptogram. In such ciphers a set of specific parameters, called a key, is supplied together with the plaintext as an input to the encrypting algorithm, and together with the cryptogram as an input to the decrypting algorithm.The encrypting and decrypting algorithms are publicly announced; the security of the cryptogram depends entirely on the secrecy of the key, and this key must consist of any randomly chosen, sufficiently long string of bits.
Read more here [qubit.org]
Re:Quantum Cryptography (Score:5, Informative)
It's similar to Schrodinger's cat: Schrodinger comprised a thought experiement where a cat was put into a sealed box with a poison and a radioactive atom. In the course of 1 hour, the atom has a 50/50 chance of decaying, thus killing the cat. At the end of the hour, the cat is neither dead or alive, but in a state of flux. It's not until you observe the system that you fix the state of the cat as being dead or alive.
magiq whitepaper (Score:5, Informative)
Forget Quantum - How can you beat Tempest (Score:2)
Now after you overcome the problem of Man in the Middle you must overcome Tempest Attacks [wikipedia.org] which captures the output radiation of electronic devices to gather sensitive data. I once saw a program that illustrated this that used two TV's side by side. One had a picture and the second one was very close and finely tuned to see the image on the fir
Solution looking for a problem (Score:5, Insightful)
New technologies gives us a nice warm feeling, but the banal truth is that what most people need is better use of existing technology.
Still, I assume spooks and crooks will be investing heavily in quantum cryptography, and we'll see the first quantum walkie-talkies within 10-15 years.
Agreed (Score:4, Interesting)
Re:Agreed - But... (Score:3, Insightful)
Here's one - it is easy to listen in on today's encrypted comms... It is easy to identify inderesting endpoints (US DOD, etc), it is cheap to write likely interesting messages to disk. A few years from now, you just set your Qomputer to decrypt all those stored comms. Just because it is in the past doesn't mean that it is stale (how old is your SSN/bank acount number/etc? How
Re:Solution looking for a problem (Score:2)
Re:Solution looking for a problem (Score:2)
Does this spell the end of the field... (Score:3, Informative)
Uh, no. Quantum key distribution is completely useless unless you have a cryptographic algorithm and protocol using that key for encryption. I suppose you could just send the message over quantum channels, but a quantum channel for key distribution is probably many orders of magnitude too slow for the acutal data.
Re:Does this spell the end of the field... (Score:5, Informative)
Re:Does this spell the end of the field... (Score:2, Insightful)
(Or do they mean that the quantum link will be transmitting OTP key continously..? How will the parties know which part of the key to use? Er ok they could transmit that on the quantum channel too... maybe it could work.)
Re:Does this spell the end of the field... (Score:3, Insightful)
Even if the link is slow it could have value in situations where burst bandwidth is greater than the QC link, but average bandwidth is not, as long as the OTP is cached. The message is sent conventionally, and as long as enough cached OTP is available it could be decrypted instantly.
QC can also be used to send symmetri
Re:Does this spell the end of the field... (Score:3, Informative)
Re:Does this spell the end of the field... (Score:2, Redundant)
In other words, in certain contexts it
Re:Does this spell the end of the field... (Score:3, Informative)
You can't just send the data over the quantum channel - it could be intercepted.
Quantum cryptography does not prevent interception of messages. It merely allows the sender and recipient to know that a message was intercepted.
So a practical QC scheme would be:
1. Send one-time-pad to recipient.
2. See if message was intercepted.
In the PDF (Score:5, Funny)
Linux already has an interface that you can move your critical documents to and they'll never be deciphered, read or copied:
Insensitive Applications (Score:5, Funny)
Quantum crypto will be very useful for insensitive financial/military applications. Example:
"All right, you worthless son-of-a-bitch -- pay your goddamned taxes, or we blow you away!"
-kgj
First thing that comes to mind... (Score:5, Funny)
Link Security (Score:3)
Re:Link Security (Score:2)
Uh Oh (Score:5, Interesting)
matter what advances occur in digital computing, quantum encryption can never
be deciphered, read or copied.
These kinds of statements always amuse me. It may be the toughest thing yet, but there's no saying that our understanding of some of the properties of quantum physics aren't flawed. Science may yet prove him wrong.
Re:Uh Oh (Score:2, Insightful)
Anyone for a game of "Cryptographic Top Trumps"??
Re:Uh Oh (Score:3, Informative)
However, quantum cryptography does not rely on large numbers that are hard to factor, but on the fact that it is impossible (according to currently known physics, as correctly pointed out) for someone to eavesdrop without being detected.
www.qubit.org has this [qubit.org] explanation:
The basic idea of cryptosystems (B) is as follows. A sequ
The statement stands (Score:3, Insightful)
Re:Uh Oh (Score:5, Informative)
Besides the Shamir attack, there's always the wait-for-your-opponent-to-screw-up attack. One time pads are theoretically unbreakable, with mathematically provable security. This didn't stop the US from reading the Venona intercepts. The Soviets had used one time pads two times, and that mistake destroyed the security.
naive (Score:2, Interesting)
I will be the first to admit that I am somewhat ignorant in this matter. My understanding is that current crypto systems rely on the fact that keys take an extremely long time to be brute forced because currently computers are not efficient at all at factoring.
As I mentioned before I am ignorant when it comes to this but doesn't it seem a little naive to say that their technology is 100% secure? I read the pdf and it sounds impressive but I still don't know about anything really being 100% secure for all t
Re:naive (Score:2)
From the article:
"MagiQ Technologies, Inc., the quantum information processing (QIP) company, today announced the general availability of its Navajo Secure Gateway, the world's first commercially available quantum key distribution (QKD) system."
Note that this product makes no claim for more than secure key distribution
Re:naive (Score:3, Interesting)
As an example of something that COULDN'T be broken, let's say you are trying to send a simply 1K text message. Now, all you need is a random 1K string that the text can be XOR'ed against. Now, this may seem pretty insecure; after all, they just have to cycle through all the possible 1K keys that you could have made to find the message. The problem is, though, t
Re:naive (Score:2)
Social Chaos and Anarchy (Score:2, Funny)
It will be the end of us all! I will *never* purchase GMO-computers They will spread into neighboring villages and corporate monopolies such as Consanto will patent with royalties accumulated on a per atom basis.
Oh, the humanity!
Theorys and more (Score:5, Informative)
Bruce Schneier doesn't care for it (Score:3, Interesting)
To quote:
This isn't new. The basic science was developed in the early 1980s, and there have been steady advances in engineering since then. I describe how it all works--basically--in Applied Cryptography, 2nd Edition (pages 554-557).
I don't have any hope for this sort of product. I don't have any hope for the commercialization of quantum cryptography in general; I don't believe it solves any security problem that needs solving. I don't believe that it's worth paying for, and I can't imagine anyone but a few technophiles buying and deploying it.
It's not that quantum cryptography might be insecure; it's that we don't need cryptography to be any more secure.
Not a question of if, but when (Score:5, Insightful)
Perhaps someone will discover a work-around to Heisenberg's uncertainty principle, or perhaps researchers will find flaws in the implementation of the algorithm. But if history is any indication of the future, quantum cryptography will eventually be cracked.
Re:Not a question of if, but when (Score:2)
Except ... with the previous ciphers you mention, it was mathematically provable that the scheme could be broken. All you needed was sufficient computing power to sift for the key. For QC the situation is reversed -- it has been proven that QC cannot be broken (*) under the laws of physics as we know them. And I hope you'll agree that changing the laws of ph
Re:Not a question of if, but when (Score:2)
Re:Not a question of if, but when (Score:3, Informative)
The one-time pad, which is only feasable by quantum cryptography, is impossible to decrypt without the key. Or rather, impossible to know which decryption is correct, as you can easily decrypt it into whatever you want.
You have no idea whet
Solving the wrong problem (Score:5, Insightful)
But these days if you want to intercept data then cracking the crypto is one of the last avenues you would try anyway. Far easier to crack the end points, suborn a trusted employee or any of the other common attacks. Security is only as strong as the weakest link. Quantum crypto merely reinforces one of the strongest links.
Re:Solving the wrong problem (Score:2, Informative)
I think that's a little too simple. The quantim crypto part is used to transmit a one-time pad, which is probably unbreakable. However, one-time pads suffer from key-distributions problems, which is where the quantum bit--no pun intended*--comes in. So it makes for a nice marriage between the two.
* A desparate punster submitted ten puns to a local newspaper to try to win the grand punster prize. His hopes were dashed, however, to find out that not only did
won't the Government just make this illegal? (Score:3, Insightful)
What the hell?.. (Score:3, Funny)
For some reason I have this vision of Gary Bussey making a drug deal...
heh - chitlenz
How quantum crypto works (Score:5, Informative)
Alice sends Bob a series of polarized photons.
There are four possibilities: -, |,
Bob sets up his polarization detector randomly so that each "qbit" is measured either for horizontal/vertical polarization or diagonal polarization. If a - or | photon hits the detector and it was set up for horizontal/vertical, he gets a good bit, otherwise a bad bit. And if a / or \ photon hits the detector and it was set up for diagonal polarization, same story. The key point is this: if the detector was set one way and the photon is polarized the other, it is in principle impossible to know its true polarization.
So Bob has a sequence of photons, some of which he knows, and some he doesn't, and he knows which are which. He sends Alice a clear-text message saying which ones he knows. Alice then encrypts the true plaintext by XOR'ing it with the values of the photons that Bob knows, using some convention like "- and / are 0, | and \ are 1".
Example:
Alice sends...: - \ - | / - | (random)
Bob's detector: + + X + X X + (random)
Bob's result..: - ? ? | / ? |
Bob's response: 1 0 0 1 1 0 1
Key...........: 0 1 1 1
If Eve tries to listen in on the photons Alice sends to Bob, she perturbs them irrevocably.
A bad description -- go buy Bruce's book for a better one.
Quantum crypto is no better than regular crypto (Score:4, Interesting)
The problem is with this cleartext message about the bases. How do you stop an intermediary from altering this message, which could hide her attempts to snoop on the photons? This is the problem of sending an authenticated message, and quantum crypto won't help you with this.
To send the authenticated cleartext message, you either need a tamper-proof channel between the parties, which is usually physically impossible, or you have to fall back on regular crypto, either public key or pre-shared key. So ultimately the supposedly unbreakable security of quantum crypto is in fact dependent on conventional cryptography. And if you're relying on conventional crypto anyway, why go to the expense of using quantum crypto?
In short, there is a great deal of hype here. When closely examined, the physical and computational requirements of quantum crypto don't make sense for the real world. You either need an unrealistic tamper-proof channel, or you rely on regular crypto and get no more security than conventional crypto gives you.
Re:Quantum crypto is no better than regular crypto (Score:3, Interesting)
A way to break it? (Score:3, Interesting)
However... What if someone were to have their own "black box", break the fiberoptic line, put one end into the receiver of their black box, and the other end out. That way you wouldn't be watching the photons go by, and affecting them. You could read them with your own black box, then re-transmit the correct photon.
Admittedly, this would be expensive, but if you are in dire need of reading something that had to be secured with quantum encryption, then money probably isn't of much concern.
Is this an incorrect assumption, or analysis on my part? I'm not a quantum physicist by any means, but I couldn't glean enough info from the articles to tell otherwise.
-Jesse
Re:A way to break it? (Score:3, Informative)
Furthermore, in accord with the Heisenberg uncertainty principle, you cannot determine all of the properties, of, for example, an electron. Knowing (measuring) one property makes the others unknowable (NOT un
Re:A way to break it? (Score:2, Interesting)
Now... Assume you wanted to transmit that data further than the 100 km. the spec lays out. You would need three black boxes, one in the middle to receive from the first, and re-transmit the data as photons to the next black box.
Can that be done? Or am I just lacking in knowledge
Re:A way to break it? (Score:3, Informative)
The "standard" use of these devices is for point-to-point communication. Put one end in the White House and the other in the Pentagon (about 40km away) and you have a communications channel that can not be sniffed without detection. So far, so good.
But this doesn't scale well. Talking from DC to Moscow would probably require some sort of relay system, just as a relay system would be r
What is the use of this QC key exchange? (Score:3, Interesting)
Re: (Score:2)
A Useful but Long Quote. (Score:5, Informative)
I have written this book partly to correct a mistake.
Seven years ago I wrote another book: Applied Cryptography. In it I described a mathematical utopia: algorithms that would keep your deepest secrets safe for millennia, protocols that could perform the most fantastical electronic interactions-unregulated gambling, undetectable authentication, anonymous cash-safely and securely. In my vision cryptography was the great technological equalizer; anyone with a cheap (and getting cheaper every year) computer could have the same security as the largest government. ...I went so far as to write: "It is insufficient to protect ourselves with laws; we need to protect ourselves with mathematics."
It's just not true. Cryptography can't do any of that.
It's not that cryptography has gotten weaker since 1994, or that the things I described in that book are no longer true; it's that cryptography doesn't exist in a vacuum.
Cryptography is a branch of mathematics. And like all mathematics, it involves numbers, equations, and logic. Security, palpable security that you or I might find useful in our lives, involves people: things people know, relationships between people, people and how they relate to machines. Digital security involves computers: complex, unstable, buggy computers.
Mathematics is perfect; reality is subjective. Mathematics is defined; computers are ornery. Mathematics is logical; people are erratic, capricious, and barely comprehensible.
The error of Applied Cryptography is that I didn't talk at all about the context. I talked about cryptography as if it were The Answer(TM). I was pretty naïve.
The result wasn't pretty. Readers believed that cryptography was a kind of magic security dust that they could sprinkle over their software and make it secure. ... A colleague once told me that the world was full of bad security systems designed by people who read Applied Cryptography.
Since writing the book, I have made a living as a cryptography consultant: designing and analyzing security systems. To my initial surprise, I found that the weak points had nothing to do with the mathematics. They were in the hardware, the software, the networks, and the people. Beautiful pieces of mathematics were made irrelevant through bad programming, a lousy operating system, or someone's bad password choice. ...
Any real-world system is a complicated series of interconnections. ... No system is perfect; no technology is The Answer(TM).
This is obvious to anyone involved in real-world security. In the real world, security involves processes. It involves preventative technologies, but also detection and reaction processes, and an entire forensics system to hunt down and prosecute the guilty. Security is not a product; it itself is a process. And if we're ever going to make our digital systems secure, we're going to have to start building processes.
A few years ago I heard a quotation, and I am going to modify it here: If you think technology can solve your security problems, then you don't understand the problems and you don't understand the technology.
This book is about those security problems, the limitations of technology, and the solutions.
Anecdote (Score:5, Interesting)
What I found rather peculiar about his view was that the reason he didn't like quantum cryptography was because it enabled organizations, such as a corrupt government perhaps, to be able to use this effectively unbreakable communication technique in order to avoid accountability to anyone else, while as long as encryption technologies remain crackable, there would always be some risk of being accountable to others for what they are communicating about.
It didn't even seem to matter to him that his own communications would be secure with this technology... he just didn't like the idea of technology introducing a break in a chain of accountability.
Re:Anecdote (Score:3, Insightful)
Also, you've still got other lines of evidence - bodies, eye witnesses, etc.
Wireless? (Score:2)
Frank Frink says... (Score:3, Funny)
I predict that quantium crypto computers will be so large as to fill an entire building, and only the 5 richest people in the world will be able to afford them
Quantum Crypto Provably Flawed? (Score:3, Interesting)
I see tons of posts stating the the link is "absolutely" secure, but it seems that isn't really the case. [dhushara.com] (see the bottom of the page.)
What strikes me about all this is the following section:
"each pulse should be attenuated to an average of about
What that says to me is that there is not way to 100% know you're transmitting just one photon.
It sounds like there's no device that is capable of transmitting one and only one photon with 100% reliability. If this is the case, a lot of the arguments about how secure this is are vastly overstated.
In the end QC would be vulnerable to a man-in-the-middle attack by watching for multi-photon emissions.
If this is the case, a lot of the noise surrounding QC could turn out to be hype. Is there a quantum physicist in the house?
Re:Of course.. (Score:4, Funny)
Nice attempt to score an easy +5 insightful...
Re:Of course.. (Score:2, Interesting)
Quantum cryptography (at least in under current theory) cannot be cracked, or intercepted, or decoded twice by two different entities. It is the king of the mountain as far as secure goes.
There are huge problems in tryin
Re:Of course.. (Score:5, Informative)
This is bullshit. First off, you have to assume that
a) non-trivial Quantum computers can be constructed at all [who says there are not limits?]
b) The time per solution is not greater than a brute force attack.
I mean sure a single cycle AES cracker would be cool. But if the machine took 2^100 years to build who gives a shit?
This type of hype always pisses me off.
To boot as I understand it, QC only "attacks" in sqrt time by meet-in-the-middle approaches. So AES-256 would provide all the security ya need.
Tom
Re:Of course.. (Score:3, Informative)
Last I heard, there is still a ton of comp-sci problems that are hard, even in the quantum world. NP problems will still be NP problems---quantum computers don't help with those.
Also, unless some really major innovations come up, we won't see quantum computers anytime soon (and I mean in centuries, not years).
Re:Of course.. (Score:5, Funny)
Quantum Crypto != Quantum Computing (Score:5, Informative)
Quantum crypto is a misnomer, it isnt even crypto at all. It's an intrusion detection system. Quantum crypto works by sending sensitive photons through a tight channel as bits which will get disturbed by an eavesdropper. Where as electrical signal on a wire expects static, and a wiretap isnt noticed.
Quantum computing however, works on electron entanglement, and is pretty far off.
Re:I was watching some TV the other day (Score:3, Funny)
Okay then, why don't you send me your credit card number in plain text then? no need to encrypt it, it's just feel-good technology, and I'm really an honest guy...
You, sir, are grossly misinformed (Score:5, Insightful)
and I can't believe anyone actually modded you up. So crypto is just a "feel-good technolog[y]" and "doesn't really do much for anyone in the end"? Have you ever used a VPN? Or SSL? Or anything in the PGP/GPG genre? Why?
Crypto is not perfect but it is extremely useful in certain situations. You apparently believe that since crypto doesn't solve all of our problems that we shouldn't use it at all.
PS If you think that "a very determined person" stealing the machine will render all crypto ineffective, you need some remedial reading on the topic. (Not a flame - just an observation.) Here is a hint: multi-level security.
Re:I was watching some TV the other day (Score:2)
For the vast majority of us who aren't doing anything that would make the military want to invade and take over the networks we're using, it's fairly effective. But thanks for the reminder that if all the technology I use gets destroyed, I should switch to a courier who's willing to die to keep my Quicken data secure.
Re:I was watching some TV the other day (Score:2, Redundant)
Unless the hard drive is encrypted, that is. Which, I suppose, is one out of many answers to my question in the write up regarding the potential future obsoleteness of traditional cryptography. QC is good for quickly passing secure messages from A to B. But sometimes, B=A, i.e. the intended recipient of the message is yourself. Then you'd probably
Re:I was watching some TV the other day (Score:3, Insightful)
Hey, a solution to the outsourcing woes (Score:2)
Because linear key improvement isn't an advantage. (Score:5, Informative)
The reason most encryption works is because when you linearly increase key size, you exponentially increase the amount of time required to crack the key if you have no special knowledge, meaning it is much more difficult (impossible for practical purposes) to decrypt without a key than encrypt or decrypt with the necessary keys.
Doubling the key size may only double the work of the one encrypting and decrypting using a key but exponentially increases the work of the one trying to break it without a key. Almost no matter how easy it is to crack a short key, you can increase key size until the advantage of linear versus exponential is overwhelming.
But quantum computing -- encoding the problem into the quantum matrix, not to be confused with the quantum encryption described in this article -- threatens to be able to solve such problems in linear time instead of exponential time.
This means that when the user doubles the size of his key instead of exponentially (enormously) increasing the amount of work to solve the problem, it only doubles the amount of work required to crack it, which would make decryption a simple footrace even if you do not have the key, if the amount of work required to crack the key is proportional to the amount of work required to encrypt / decrypt instead of an exponential relationship.
Primes would not seem to be adequate at all, if quantum computing allows them to be solved linearly. At best, if you could find something that had the difficulty of non-quantum primes under quantum computing, then perhaps you could use that.