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Scientific American on Quantum Encryption

samzenpus posted more than 9 years ago | from the just-try-and-break-it dept.

Security 374

prostoalex writes "Scientific American claims that advances in commercially available quantum encryption might obsolete the existing factorization-based solutions: "The National Security Agency or one of the Federal Reserve banks can now buy a quantum-cryptographic system from two small companies - and more products are on the way. This new method of encryption represents the first major commercial implementation for what has become known as quantum information science, which blends quantum mechanics and information theory. The ultimate technology to emerge from the field may be a quantum computer so powerful that the only way to protect against its prodigious code-breaking capability may be to deploy quantum-cryptographic techniques.""

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Unbreakable Encryption... (5, Funny)

Jace of Fuse! (72042) | more than 9 years ago | (#11417111)

Someone needs to write a Encryption routine that uses the source text as the key. THAT will really show 'em!

Re:Unbreakable Encryption... (1)

bryan986 (833912) | more than 9 years ago | (#11417154)

It actually took me a second to figure that one out, probably why im at -1

Re:Unbreakable Encryption... (0)

Anonymous Coward | more than 9 years ago | (#11417297)

Well thats really not ay use, why would you encypt something if who had to use the encypted part tyo unencypt it?

Re:Unbreakable Encryption... (0)

Anonymous Coward | more than 9 years ago | (#11417472)

thats why it's funny..

Re:Unbreakable Encryption... (5, Funny)

Paul Crowley (837) | more than 9 years ago | (#11417521)

Already done - XORing the source text with itself is a provably perfectly secure form of encryption!

Don't verb adjectives (0)

Dancin_Santa (265275) | more than 9 years ago | (#11417113)

And who's to say that the NSA hasn't had this technology available to them for a while?

And if they have quantum encryption, their quantum decryption (code breaking) devices are probably a little more advanced than what those two companies *cough*flybynight*cough* are selling.

Re:Don't verb adjectives (0)

Anonymous Coward | more than 9 years ago | (#11417166)

I personally believe IBM has made more headway in the Quantum front than either both of those companies OR the NSA, and IBM still claims Quantum Computers are still some time off.

In short, I believe IBM to be more competent than the NSA, though that isn't saying much.

Posting AC so they don't bump me off.

Re:Don't verb adjectives (5, Insightful)

Anonymous Coward | more than 9 years ago | (#11417262)

God, I love when slashdot covers advanced scientific stuff... then people like you who have no idea what they are talking about get to be mod'ed Insightful!

OK, there's two very different uses of quantum technology when applied to crypto problems:

1. If you had a quantum computer some problems like factorization become easy; therefore things like RSA would be instantly decryptable. The gotcha is that the current "state of the art" for quantum computers are still absolutely tiny and there are HUGE engineering challenges towards building one large enough to factor a real key (I think they're at the point now where they can factor numbers like "12"... so they have a bit of scaling before they can start attacking 300-digit numbers)

Of course there could be a massive breakthrough in quantum computer design tomorrow which would throw the whole crypto world on its head. That makes this area really interesting for crypto people.

Does NSA secretly have a quantum computer that can do that? I'd say its extremely unlikely... I'm sure they have people looking into it but they would have to be AMAZINGLY far ahead of the public research community to have actually built a full-size one.

2. What this article is talking about is "quantum encryption" what's really "quantum" about it is making an untappable fiber line by signalling using the characteristics of single photons. By using Heisenberg's uncertainty principal you can make it impossible for anyone to tap the line (and thus observe the photon states) without also randomizing the bits. It's really hard to get your head around but it actually works.

Note that nowhere here did we use a "quantum computer"... this is all using technology that exists today (obviously, since you can buy it)

So basically even if your adversary has a trillion dollar budget to attack you with they CANNOT tap that fiber line without destroying the communication in the process. It's physically not possible with any technology.

So unless the NSA has a whole undiscovered field of physics that the world doesn't know about they don't have "quantum decyption" As we understand physics today it's literally impossible to build such a device.

Re:Don't verb adjectives (1)

krymsin01 (700838) | more than 9 years ago | (#11417293)

Uh, don't you know about Area 51? You didn't get the memo, eh?

Re:Don't verb adjectives (3, Interesting)

dragons_flight (515217) | more than 9 years ago | (#11417320)

I don't think that the NSA has substantially better quantum encryption / computing than the rest of us. My main line of evidence is that they are still throwing enormous gobs of money at unclassified research into quantum computing.

One such example is the innocuously named "Laboratory for Physical Sciences [umd.edu] ". Please note the rather conspicuous key-shaped logo. I toured their facility a few years back while looking for a job. At the time the NSA was buying them just about anything they wanted provided it might have applications in quantum computing. This included a rather sophisticated chip fabrication lab and clean room.

I don't know if we will ever really have quantum computers, but the NSA sure doesn't want to be late to the party if we do.

Re:Don't verb adjectives (1)

OzRoy (602691) | more than 9 years ago | (#11417386)

It is impossible to crack quantum encryption.

It's a bit of a misleading name, but the actual encryption part of these techniques is the one time pad which has been a known technique for a long time now. It is mathmatically proven to be impossible to break a one time pad as long as you use a truely random key.

The quantum part of this new technique is just the method of transmitting the key to the other person. With it you can guarantee that no one else has listened in and knows what the key is.

Re:Don't verb adjectives (0)

Anonymous Coward | more than 9 years ago | (#11417424)

Actually, you can't guarantee that no one else listened. But you can make the probability of detecting a listener as close to 1 as you wish.

Re:Don't verb adjectives (0)

Anonymous Coward | more than 9 years ago | (#11417475)

> It is impossible to crack quantum encryption.

Not exactly. What's impossible at the time is to catch the message without altering it, that is, the expected receiver will see that there is a man in the middle.

> The quantum part of this new technique is just the method of transmitting the key to the other person. With it you can guarantee that no one else has listened in and knows what the key is.

Yeah. But you need a really random key : if not, one might observe flow of qbits, forcing alice to choose another key, and deduce after some time what will be the next pseudo-random key.

Re:Don't verb adjectives (0)

Anonymous Coward | more than 9 years ago | (#11417492)

How?? The act of "observing" any infomation tranfered between two parties in this manner would disrupt it. You would have to figure out how to get around the uncertianty principal; and that to my knowlege has not been done.

n.b does not hurt cats unless you observe them (5, Funny)

Engineer Andy (761400) | more than 9 years ago | (#11417114)

As far as I can tell, no cats were harmed in the making of these quantum cryptographic devices, although if you look inside the box, the act of looking at the cat inside may (or may not) kill it

Re:n.b does not hurt cats unless you observe them (0)

Anonymous Coward | more than 9 years ago | (#11417134)

As far as I can tell, no cats were harmed in the making of these quantum cryptographic devices

Yeah well...

cat /dev/null >/bin/cat

hmmm, would that even work?

Re:n.b does not hurt cats unless you observe them (1)

Z4rd0Z (211373) | more than 9 years ago | (#11417212)

Sure it would work, why not? As long as you had the right permissions, I reckon.

Uhh... (1)

Ziviyr (95582) | more than 9 years ago | (#11417115)

Why does quantum computing threaten present encryption?

Re:Uhh... (4, Informative)

k98sven (324383) | more than 9 years ago | (#11417130)

Because you could implement Shor's factorization algorithm [senko-corp.co.jp] .

Re:Uhh... (1)

ciroknight (601098) | more than 9 years ago | (#11417534)

So.. I really don't understand quantum computing. Why doesn't someone build a emulator that would allow a large grid of existing computers to run a "quantum computer"? Wouldn't it be just as easyto delegate a processor to six or seven bits at a time?

*puzzled*.

Re:Uhh... (1)

Jace of Fuse! (72042) | more than 9 years ago | (#11417133)

Why does quantum computing threaten present encryption?

Because the potential to try every possible key at once could exist in a sufficiently advanced Quantum Computer.

Re:Uhh... (1)

Ziviyr (95582) | more than 9 years ago | (#11417172)

Because the potential to try every possible key at once could exist in a sufficiently advanced Quantum Computer.

Great, so you can get quadrillions of improperly decoded versions and one good one, hidden in there somewhere. For any good encryption, I don't see how that helps much.

Re:Uhh... (5, Insightful)

tftp (111690) | more than 9 years ago | (#11417436)

If you have a ton of sand with some gold nuggets mixed in, it's kinda tedious to manually inspect every grain of sand and throw it away if it doesn't look like gold.

However, it is perfectly reasonable to borrow a large sieve with a water tray - which both work on all the grains simultaneously - and then the job becomes doable in hours.

Re:Uhh... (1)

drgonzo59 (747139) | more than 9 years ago | (#11417493)

That is one of the best analogies I've heard about the idea behind quantum superposition and how it would work with factorization.

Re:Uhh... (1)

glenkim (412499) | more than 9 years ago | (#11417438)

The grandparent's explanation was a little lacking on details. What he meant was with a quantum computer, encryption which relies on the computational infeasibility of the factorization of large prime numbers multiplied together can be easily cracked. You can attempt every possible number in one iteration, thus finding the prime numbers that comprise the key and rendering the encryption useless.

Re:Uhh... (1)

ageitgey (216346) | more than 9 years ago | (#11417481)

Great, so you can get quadrillions of improperly decoded versions and one good one, hidden in there somewhere. For any good encryption, I don't see how that helps much.

The machine knows that it found the plaintext because it looks like plaintext. [linuxsecurity.com]

Basically, the longer the message is the less chance you have of finding a key that produces a reasonable but incorrect plaintext.

Re:Uhh... (1)

Harry Balls (799916) | more than 9 years ago | (#11417138)

Because a Qbit (quantum bit) is both 0 and 1 at the same time, until observation forces it to a known state.
Hence, a register built out of 512 Qbits represents 2^512 states at once and you can brute-force RSA or DSA encryption algorithms.
However, right now it is not yet feasible to build a quantum computer with 512 Qbits.

Re:Uhh... (0)

Anonymous Coward | more than 9 years ago | (#11417531)

It's not known that you can use a QC for brute-forcing RSA or DSA. However, you can crack RSA by factoring the public key with Shor's algorithm, which is one of only two algorithms known to run on quantum computers.

Re:Uhh... (4, Funny)

monkease (726622) | more than 9 years ago | (#11417140)

Quantum computing doesn't make threats.

It makes promises.

I'm not just gunna break yo' face, i'm going to quantum break yo' face, foo'!

Re:Uhh... (4, Funny)

gl4ss (559668) | more than 9 years ago | (#11417160)

*I'm not just gunna break yo' face, i'm going to quantum break yo' face, foo'!*

so you gonna break his face and slam a cardboard box over his head? "no officer, his face is not smashed. however, if you take the box off it might cause it to be smashed or not"

Re:Uhh... (2, Funny)

monkease (726622) | more than 9 years ago | (#11417173)

And then I'll quantum-borrow the cop's glock and quantum-unload a clip into the box.

I quantum-love science!

Re:Uhh... (5, Informative)

Dr. Weird (566938) | more than 9 years ago | (#11417152)

Encryption, as it stands now (the classical kind), relies on an asymmetric computational task. For example, it is much easier to check that the a list of numbers are the factors of another number than it is to factorize the number. In fact, the latter is, to the best of current computer science knowledge, exponentially slower than the first.

Quantum computing provides an algorithm (Shor's), utilizing quantum mechanical manipulations, which factors numbers exponentially faster. Thus, factoring and checking factors takes the same amount of time.

This leads to the undesirable conclusion that encryption and decryption (by an intercepting 3rd party) of a signal take the same amount of time (up to a polynomial equivalence). In other words, the encryption is breakable, since the interceptor need only invest roughly the same amount of computational effort as the sender in order to crack the message.

That is why the creation of a quantum computer would "obsolete" present encryption. The point of quantum encryption is that it is not vulnerable to such attacks.

Re:Uhh... (3, Informative)

Anonymous Coward | more than 9 years ago | (#11417455)

But, as usual, the media hypes this too much. Presently only two useful algorithms for quantum computers are known. A search in an unordered set, which runs as sqrt(N) (as compared to N for traditional computers), and Shor's algorithm for factoring numbers. The most widely used public key cryptography (RSA) is based on the difficulty of factoring numbers, but it would not be technically difficult to replace it with another asymmetric scheme, e.g. based on elliptic functions. No quantum algorithms are known which obsoletes this.

Re:Uhh... (2, Informative)

Omniscientist (806841) | more than 9 years ago | (#11417175)

Well with current encryption methods you usually have a public key and a secure key. Let's say I give everyone here my public key. Well then everyone can encrypt me messages, but only I can decode it with my secure key. However within that public keys lies the secrets of the secure key, but it would take an extremely long time to break the public key cipher. With quantum computing, which can perform really hard factorizations quickly, it would make the whole many current cryptographic schemes obsolete, because it would be so easy to crack the public key. Therefore the only solution to this is the introduction of quantum cryptography, which would theoretically be able to avoid being cracked easily, RTFA for more.

Re:Uhh... (1)

Ziviyr (95582) | more than 9 years ago | (#11417208)

Public keys didn't strike me as invincible to begin with...

Re:Uhh... (2, Funny)

vagabond_gr (762469) | more than 9 years ago | (#11417538)

VERY rough explanation.

Encryption algorithms rely on the fact that some problems need an exponential number of 'calculations' to be solved. If b is the number of bits in a key, breaking the encryption needs 2^b steps.

On the other hand in traditional computers, if you have p processors and each can perform n calculations per time unit, then you can perform p.n calculation in total. Increasing p or n gives only a *linear* improvement in performance. This is not enough to match 2^b if b is big enough.

On the other hand with q Qbits you can perform 2^q calculations simultaneously (nature's miracle). Take b Qbits and you're done (I said rough explanation, remember). The only problem is that its VERY dificult to tie QBits together.

fp (0)

Anonymous Coward | more than 9 years ago | (#11417117)

Too bad that once the connection channel is completely secure (with quantum cryptography), people who *really* want to read the information will find otehr ways around it, i.e. infiltration, burglary, etc.

Re:fp (1)

OzRoy (602691) | more than 9 years ago | (#11417399)

If you actually read the article you would see that they acknowledge that problem. But that is a problem that will always exist, and has always existed.

And an inside job will always prove unstoppable. "Treachery is the primary way," observes Seth Lloyd, an expert in quantum computation at the Massachusetts Institute of Technology. "There's nothing quantum mechanics can do about that."

Arm's Race (1)

Walker2323 (670050) | more than 9 years ago | (#11417119)

The arm's race continues. Then they'll have to invent Super Turbo Quantum Mofo Encryption to stay one step ahead.

Re:Arm's Race (0)

Anonymous Coward | more than 9 years ago | (#11417132)

Was it the left arm, or the right arm's race.

OH, you mean ARMS race.

The incorrect usage of the apostrophe threw me.

Re:Arm's Race (0)

Anonymous Coward | more than 9 years ago | (#11417167)

I wish it threw you a bit harder. Ohh snap!

Re:Arm's Race (1)

databyss (586137) | more than 9 years ago | (#11417155)

This will surely be outpaced by Time-Travel-Plus-Teleport Encryption, where you beam yourself to the time and place you need the information and hand it off.

i once read.. (1)

KingPunk (800195) | more than 9 years ago | (#11417123)

a book on encryption and all the good stuff associated with it
and the book's main point was that, while encryption is generally great,
given time, no encryption has ever stood..

its just a matter of time, until "Quantum Encryption" takes its place among these facts too.

Re:i once read.. (1)

OzRoy (602691) | more than 9 years ago | (#11417410)

There is one encryption that has always stood and that is the one time pad.

A properly implimented one time pad using a truly random key is impossible to crack.

Quantum encryption is based on the one time pad, and it overcomes the weakness of how you guarantee your key has been transmitted to the other person without anyone else knowing it.

Eve? (0)

Anonymous Coward | more than 9 years ago | (#11417126)

If someone tries to intercept this stream of photons--call her Eve--she cannot measure both modes, thanks to Heisenberg.
What happened to Trudy?

Re:Eve? (0)

Anonymous Coward | more than 9 years ago | (#11417176)

The cast [wikipedia.org]

Whole Article, One page (4, Informative)

chadw17 (308037) | more than 9 years ago | (#11417127)

The printer-friendly version puts it all on one nice and image free page.
Article here [sciam.com]

Heisenburg (0)

Anonymous Coward | more than 9 years ago | (#11417131)

The ultimate technology to emerge from the field may be a quantum computer so powerful that the only way to protect against its prodigious code-breaking capability may be to deploy quantum-cryptographic techniques.

It's already available in some universes. Which is why R&D for quantum computers is one of the best jobs you could possibly get; you just hang around until one pops up.

Re:Heisenburg (1)

djupedal (584558) | more than 9 years ago | (#11417425)

you just hang around until one pops up

Actually, following Heisenburg dictum (using analog methods, of course), it's more along the lines of you popping up where it is - make sure to wear clean underware at all times while you wait.

Anyone seen John? He was right here a minute ago...

Quantum Encryption (1)

Ziwcam (766621) | more than 9 years ago | (#11417144)

I think this is only another example in a long line of encryption that was quite secure when envisioned, but then as computers became more and more powerful, became less and less secure. Eventually, we will have quantum computers capable of brute-forcing even quantum encryption...

Re:Quantum Encryption (5, Insightful)

k98sven (324383) | more than 9 years ago | (#11417220)

I think [..] Eventually, we will have quantum computers capable of brute-forcing even quantum encryption...

Well, you think wrong. Quantum encryption cannot be 'brute-forced'. Because it's not 'encryption' in the conventional sense but rather 'secure transmission'. The data is not encoded, but rather transmitted in a way which makes eavesdropping impossible. Since you can't intercept any 'coded message', there is nothing for you to brute-force.

And this holds as long as what we know of quantum mechanics holds.
(More specifically, the Bell inequality [ucr.edu] . Which was verified in the famous Aspect experiment.)

So no, nothing in quantum physics is going to invalidate quantum encryption. And I wouldn't get my hopes up for future theories, either, because this 'wierdness' of quantum mechanics so well-verified experimentally that it'd be unlikely that any future theory would change it. (But hopefully explain it)

Re:Quantum Encryption (1)

OzRoy (602691) | more than 9 years ago | (#11417431)

No that is not quite right.

You still encrypt the final message. All the quantum part does is tell you when a third party has intercepted your data stream. It does not prevent a person from reading it.

So what you do is you generate a random key and transmit that to the other person. The key is random junk that will be used to encrypt the final message. If a person reads this you can detect it and all you do is recreate the key and try again.

You just keep trying to send a new random key until it is sent without anyone reading it. Once it is sent successfully you encrypt your message using it, and transmit the newly encrypted message to the other person using traditional methods.

A person is free to intercept this message because it's not possible to brute force a message using a truly random key.

Re:Quantum Encryption (1)

menscher (597856) | more than 9 years ago | (#11417237)

Eventually, we will have quantum computers capable of brute-forcing even quantum encryption...

No, we won't. It's an interesting thought, but it doesn't work that way. According to the laws of physics (as we currently understand them) quantum encryption, if done properly, is provably secure. That is, there is no way to break the encryption, unless quantum mechanics itself is flawed.

Of course, there are other attacks. For example, QC (quantum cryptography) requires you to pick the polarization basis randomly. If you don't pick it randomly enough then there's a bias that could potentially be exploited by an attacker. And it's difficult to be random at high speeds, so QC will probably be limited to slow speeds, at least at first.

The real problem with QC is that it requires a point-to-point transaction, with no repeaters. So it doesn't really work with the internet. Still, it could be useful for Whitehouse-to-Pentagon communications, or other similar setups.

Re:Quantum Encryption (1)

arose (644256) | more than 9 years ago | (#11417307)

The real problem with QC is that it requires a point-to-point transaction, with no repeaters.
And that's where the "axe in the middle" attack comes in.

Re:Quantum Encryption (1)

fodderb0y (301077) | more than 9 years ago | (#11417366)

The point that these two guys are alleging, btw, is Heisenberg's Uncertainty Principle which states that observation of a particle changes the probability of it's existence to virtually zero.

So, if one were to attempt to 'brute force' attack a quantum crypto-stream, one would have to have had to receive a copy of that stream before it hit the 'quantum wire', ie before it reached the point where quantum mechanics superceded the laws of the seeable, knowable universe.

Not impossible, but not likely either.

Once again, Slashdot and it's readers manages to fuck up a fantastic article written months in print.

Looks like you assholes need to learn how to read.

Re:Quantum Encryption (1)

l0b0 (803611) | more than 9 years ago | (#11417251)

Eventually, we will have quantum computers capable of brute-forcing even quantum encryption...

IIRC from The Code Book [amazon.com] , you can have basically unbreakable crypto-algorithms. The clue is to make the key as long as the message (thereby wasting 50% bandwidth, but what the heck). Then, if the key is properly randomized, any attempt to decrypt it will result in _all_ messages of that size, which basically means that for most purposes, decryption will not result in any useful information.

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LOP's? (1)

ackthpt (218170) | more than 9 years ago | (#11417150)

The ultimate technology to emerge from the field may be a quantum computer so powerful that the only way to protect against its prodigious code-breaking capability may be to deploy quantum-cryptographic techniques

How about they just issue LOP's on silk?

Re:LOP's? (0)

Anonymous Coward | more than 9 years ago | (#11417286)

LOP?

Loss of pointer?
Line of path?
Logical operation plan?
Low on power?
Least objectionable program?
Language oriented programming?
Letter of permission?
Local Office Policy?

Pretty gooder privacy (1)

liangzai (837960) | more than 9 years ago | (#11417156)

I for one welcome our new quantum-cryptographical overlords.

Bah... (2, Funny)

JohnPerkins (243021) | more than 9 years ago | (#11417161)

tshtuatpptenaynrirragagcuoyomq

sweet upgrade (2, Funny)

g0dsp33d (849253) | more than 9 years ago | (#11417162)

so long bits, hello tits.

Trinary digITs here we come!

FUNNY not OT (1)

TapeCutter (624760) | more than 9 years ago | (#11417461)

Even though the T in tits stands for Ternary, modding the parent OT displays a humourless soul.

Good for telco's? (1, Interesting)

afidel (530433) | more than 9 years ago | (#11417169)

Will the need for an unbroken end-to-end light pipe finally lead to enough demand to light up some of that dark fibre that is sitting on the telco's books?

Baloney. (5, Interesting)

Pendersempai (625351) | more than 9 years ago | (#11417177)

Quantum cryptography is a solution in search of a problem. It cannot implement public key/private key cryptography, and it can transmit only through a single uninterrupted fiber-optic cable, not over the internet at large. Given those limitations (which I don't think can be surmounted), one might as well use tremendous, digital one-time pads. Transmission of the pads to the relevant parties should be strictly easier than the quantum cryptographic solution: if nothing else, generate terabytes of noise, store it on a RAID, and put it in a car with ten intensely loyal guys. After you've done that, you can send up to that amount of data securely over the internet at large, and no amount of quantum hocus-pocus will be able to decode it.

Re:Baloney. (1, Funny)

Anonymous Coward | more than 9 years ago | (#11417201)

Oh my God, you're right. We will stop our work immediately, I can't believe we didn't think of this before.

-- Charles Bennett

Re:Baloney. (1)

Dr. Photo (640363) | more than 9 years ago | (#11417394)

Transmission of the pads to the relevant parties should be strictly easier than the quantum cryptographic solution: if nothing else, generate terabytes of noise, store it on a RAID, and put it in a car with ten intensely loyal guys.

I like this proposal. Companies who can't find ten intensely loyal employees probably don't deserve to have secrets. ;-)

Re:Baloney. (0)

Anonymous Coward | more than 9 years ago | (#11417427)

No Public key Crypto. Less distance than the internet. Lame.

Re:Baloney. (4, Insightful)

OzRoy (602691) | more than 9 years ago | (#11417441)

I quote the apropriate part from the article for the lazy parent who has not RTFA.

Ultimately cryptographers want some form of quantum repeater--in essence, an elementary form of quantum computer that would overcome distance limitations. A repeater would work through what Albert Einstein famously called "spukhafte Fernwirkungen," spooky action at a distance. Anton Zeilinger and his colleagues at the Institute of Experimental Physics in Vienna, Austria, took an early step toward a repeater when they reported in the August 19, 2004, issue of Nature that their group had strung an optical-fiber cable in a sewer tunnel under the Danube River and stationed an "entangled" photon at each end. The measurement of the state of polarization in one photon (horizontal, vertical, and so on) establishes immediately an identical polarization that can be measured in the other.

And it continues on this page http://www.sciam.com/article.cfm?chanID=sa006&arti cleID=000479CD-F58C-11BE-AD0683414B7F0000&pageNumb er=3&catID=2

Re:Baloney. (0)

Anonymous Coward | more than 9 years ago | (#11417477)

Uh, what do you then need the key for? If you have a method for transmitting the key securely, why not transmit the message instead?

Re:Baloney. (1)

wwest4 (183559) | more than 9 years ago | (#11417478)

> It cannot implement public key/private key cryptography

In terms of cryptography only, quantum is next-gen. It obsoletes assymetric key crypto.

> one might as well use tremendous, digital one-time pads.

Except that OTPs are insecure without a quantum key exchange.

> generate terabytes of noise, store it on a RAID

Storing the key to a one-time pad would just be stupid.

> no amount of quantum hocus-pocus will be able to decode it.

An attacker won't need quantum hocus-pocus if you generate the key insecurely and then store it.

Re:Baloney. (1)

tftp (111690) | more than 9 years ago | (#11417480)

Given those limitations (which I don't think can be surmounted)

Think outside of the box. Bounce the laser light off of a satellite. Directly communicate with planets and spaceships. That's where most of the communication will be occurring within 100 years.

Re:Baloney. (2, Informative)

imagin8or (676287) | more than 9 years ago | (#11417504)

In the world of cryptography, there is no greater problem than key distribution. If I have a bank, and I want a secure connection to the head office, I need a big enough one-time pad to cover all the transactions for, say, a month. This is nigh-on impossible, as the amount of data is too huge. It also creates a huge weak point in the whole operation in allowing someone to infiltrate the courier, block deliveries, copy the data, etc. Public key cryptography (mainly via RSA) was the answer to that problem. A public server can hold people's public keys, and only the intended recipient can read messages encrypted with them. So now, RSA is used to encrypt the key for a symmetric cryptosystem which is subsequently used. Quantum computing, however, breaks that security by making the private key available from knowing only the public key. Sure, the devices are not that big yet, but people like those I work for are working on scaleable technology that will put large devices within reach. Sure, for most people, it's not an issue. Only people with million-dollar quantum computers could break their encryption and steal their credit card data. But governments still need secure communication, and banks still need to secure their transactions. So for those with a serious need, there is Quantum Key Distribution, as outlined in the article. QKD is not 'breakable' in any sense. You cannot only intercept the classical communication channel and somehow obtain the original data. The only possible attacks are based on good access to the fibre used for the quantum key. Some of us can see methods of intercepting the key with various degrees of success if you can get to the fibre. The easier ones rely on non-ideal implementation of the method - multi-photon bursts, polarisation dependent fibre, insensitivity to mode biasing. Oh, and the traditional piggy-in-the-middle trick is (and always will be) entirely undetectable.

Wait till DVD Jon hears about this (2, Funny)

julie-h (530222) | more than 9 years ago | (#11417181)

"Jon, we have a situation. We need your to do your stuff."

Google Image Search Is Broken!! (-1, Offtopic)

Anonymous Coward | more than 9 years ago | (#11417184)

I searched for "cheerleaders" and like no pornographic images came up! I was like WTF! I was able to find an image http://britton.k12.mi.us/~marcuss/colts/images/che erleaders.jpg [k12.mi.us] to jerk off too. I regret it now since I kinda messed up my keyboard and I think it was illegal because the girls were underage.

TFA is quite ..umm.. cryptic (2, Informative)

Gopal.V (532678) | more than 9 years ago | (#11417190)

Eventhough it looks as if it has been written for a layman , the article is quite cryptic (and IMHO nothing new).
If someone tries to intercept this stream of photons--call her Eve--she cannot measure both modes, thanks to Heisenberg. If she makes the measurements in the wrong mode, even if she resends the bits to Bob in the same way she measured them, she will inevitably introduce errors. Alice and Bob can detect the presence of the eavesdropper by comparing selected bits and checking for errors.
Ok, if you use a single photon to send the information , it cannot be eavesdropped. But in the current networks it'll only go around a couple of meteres at Max and you can't use an amplifier/repeater with this. So really, how are we going to use this in real life ?. The concept has been there for decades now - ie an OTP created with entropy drawn from the quantum uncertainity rather than just psuedo random codes.

The real advantage of using entangled photons would be in sending information faster than light. [ucr.edu] Entangled Photons in Computers [sciencedaily.com] actually might solve all the copper issues in speed we're having in chip DIE size vs clock speed (as in how to get a signal from one end of the chip to the other in a single clock signal).

Re:TFA is quite ..umm.. cryptic (4, Insightful)

Anonymous Coward | more than 9 years ago | (#11417276)

But in the current networks it'll only go around a couple of meteres at Max and you can't use an amplifier/repeater with this. So really, how are we going to use this in real life ?

Who said using it on current networks? In real life, custom networks are used, of course.

Sending information faster than light is likely not possible. The FAQ you linked to says that too. Currently, theory says no, and experiment can't tell. Some have chosen to interpret their experiments as supporting FTL transmission of information. But the majority do not agree with that interpretation.

Using photons in computers in any form is so far off that suggesting it as a solution to current day problems like die size vs clock speed is ridiculous.

what, me worry? (2, Funny)

LiquidMind (150126) | more than 9 years ago | (#11417216)

"...a quantum computer so powerful that the only way to protect against its prodigious code-breaking capability may be to deploy quantum-cryptographic techniques."

scary stuff....however, a simpsons quote comes to mind:

Alien 1: It seems the earthlings won.
Alien 2: Did they? That board with a nail in it may have defeated us. But the humans won't stop there. They'll make bigger boards and bigger nails, and soon, they will make a board with a nail so big, it will destroy them all!
[both aliens laugh evilly, for quite some time]

It's all a game (1)

pele_smk (839310) | more than 9 years ago | (#11417227)

Is this new? A proof of concept for any encryption cracking should be a video game patch. So it stands on top for a couple hours, only to be knocked down by crackers a short time later. Is this really something new? Every time a new patch comes out it's like the world expects it to stop everything.

Lets be realistic, if we didn't leave our trash on the table at the mall where would the guy that gets paid to clean it up go? Same with security. If we didn't have people to break into stuff, where would all the security professionals go? There's no stopping it, might as well enjoy it. Keep quantum costly and that will be its firewall, keep quantum available to only the elite and that will be the encryption, put it on newegg and watch me buy one, meaning the technology is no longer useful and has been hacked.

I truly don't see how anything that travels outside of ones' self could ever be secure. As soon as your password reaches your fingertips and is typed, data is no longer secure.

heard that before, somewhere... (0)

djupedal (584558) | more than 9 years ago | (#11417232)

'a quantum computer so powerful'

See those fjords? Those are mine!

Ridiculously overblown (1, Insightful)

eddeye (85134) | more than 9 years ago | (#11417247)

Quantum "encryption" is for the most part useless. It's just another way to exchange symmetric keys. The advantages are purely information-theoretic; in the real world, classical methods are just as good and a whole lot cheaper.

It's like replacing a steel deadbolt with titanium, meanwhile the door is wooden, the hinges are brass, and there's a large window right next to it.

The only possible uses are extremely high-value applications like banking and the military. Even then I'd spend my money elsewhere.

The breaking RSA stuff is unrelated (quantum computers, not quantum key exchange) and pure speculation. RSA isn't going away for a loooong time.

Re:Ridiculously overblown (3, Insightful)

adamruck (638131) | more than 9 years ago | (#11417352)

If my understand is correct, which I think it might be, then you are completely wrong.

Quantum encryption is not about exchanging keys, its not even encryption in its normal sense. What it really is, is secure trasmission.

Secure meaning, nobody can read this data during transmission other than the reciever without it being physically impossible to notice.

Re:Ridiculously overblown (0)

Anonymous Coward | more than 9 years ago | (#11417448)

Quantum encryption is most definatly not about secure transmission.

With this setup, you don't even get to choose which data you send. But both parties get the same data.

That data is used as a key, with which the information is encrypted, and then the encrypted information is transferred in a more traditional way.

OK?

Re:Ridiculously overblown (0)

Anonymous Coward | more than 9 years ago | (#11417530)

> Quantum encryption is not about exchanging keys, its not even encryption in its normal sense. What it really is, is secure trasmission.

There is somewhat a contradiction in that statement : I agree, quantum encryption is about secure transmission.
But it is also about exchanging keys : with it you can exchange keys securely. When you're certain your keys were not intercepted, you can then send the message encrypted with these keys, maybe with a more classical mean of communication

Re:Ridiculously overblown (2, Informative)

OzRoy (602691) | more than 9 years ago | (#11417454)

Classical methods are not just as good.

Any public-private key encryption can be broken through brute force. What keeps them secure is that most of the time it takes a long time to break them.

With the development of quantum computers (which some people believe can be done within the next 20 years) it will only take a few seconds to break ANY public/private key encrypted message.

A message sent using quantum encryption cannot be broken by brute force.

That's not what the Uncertainty Principle says (2, Informative)

Anonymous Coward | more than 9 years ago | (#11417255)

If someone tries to intercept this stream of photons--call her Eve--she cannot measure both modes, thanks to Heisenberg.

That's wrong. The Uncertainty Principle merely states that an observer cannot measure both position and momentum with arbitrary precision.

Re:That's not what the Uncertainty Principle says (4, Informative)

jericho4.0 (565125) | more than 9 years ago | (#11417470)

Actually, it's more general than that, and applies to other mesurables (noncommuting observables) of a quantum mechanical system. In this case, spin.

Re:That's not what the Uncertainty Principle says (0)

Anonymous Coward | more than 9 years ago | (#11417496)

The point is that once you measure the photon, its state collapses to what you measured. Collapsed states can be detected by checking the Bell inequality.

Slash site about Quantum Information Theory (0)

Anonymous Coward | more than 9 years ago | (#11417268)

Not strictly ontopic, but worth to mention: QubitNews [fis.ucm.es] , a slash site on quantum computers and quantum information, is getting some activity lately. Drop by once in a while, if you are interested. You might read some insightful comment from insiders of the field!

Quantum Encryption is Not Encryption (4, Informative)

Uhlek (71945) | more than 9 years ago | (#11417272)

Quantum encryption is a misnomer, it should be called (and is, in some circles) quantum key distribution. It's all about how the key is transmitted, not how the data is secured. The encryption method is independant of how the key is distributed. Contrary to popular belief, it typically cannot be a one-time pad, since the bandwidth on the "key" channel is very limited due to the exact nature of the transmission. It can be, though, a constantly shifting AES key, or other type of data, making the datastream as a whole effectively unbreakable.

The problem lies in that you have to have a single, unbroken fiber optic connection between the two points, and this fiber optic connection is very limited in the amount of loss that it can withstand. That means you're geographically limited on how far the circuit might be able to travel. You're looking at a few hundred kilometers, at the absolute maximum.

Considering the amount of money you'd spend on putting the circuit in place versus the amount of money you'd lose if the data was compromised, it's very unlikely that anyone, anywhere will have a practical use for QKD/QE. Government and defense, maybe, but then only in very limited applications.

There is a chance that, should quantum computing become a reality and modern encryption algorithms can suddenly be cracked very, very easily that this method may see some use, and by no means is development a waste of time and effort. But, QC is still very much in the early stages, if a working system is ever developed at all.

Thta being said, PKI and courier delivery of key material will continue to be the order of the day for quite some time.

Re:Quantum Encryption is Not Encryption (1)

tftp (111690) | more than 9 years ago | (#11417512)

PKI and courier delivery of key material will continue to be the order of the day for quite some time

Unless you want to have a completely secure network of computers. Make a grid out of them and you cover the whole country. Every node will have to be as secure as the origin and destination, but likely these will be the nodes themselves, so no harm done. Also it may be possible to use layers of encryption, so that every node to node link carries message encrypted for some other node, and thus no single breach can reveal the message.

No courier can be as efficient as a country-wide network with near-instantaneous transmission times. Any government, any military would want it.

I don't know if I can make this clear, but I'll (5, Informative)

whimsy (24742) | more than 9 years ago | (#11417323)

give it a shot.

Particles that are treated best by quantum theory (such as photons, here) exhibit quantum states. Just think of them as metainformation about the particle, which is accurate to a first approximation and appropriate for this explanation. In this case, the light is polarized, which dictates some of its quantum metainformation.

The Heisenberg principle, which you've probably heard about, says that you cannot know the position and momentum of a particle exactly, simultaneously. You can know one or the other exactly, you can know both with noninfinitesimal error, but you can't know both. For big, heavy things, like macroscopic objects, the uncertainty is so small as to be irrelevant.

The quantum weirdness which results is as follows: an unobserved object simultaneously exists in a linear combination of multiple quantum states. That is, it exists as

(x*A+y*B+z*C)/(x+y+z)

Where A,B,C are quantum states and x,y,z are relative probabilities. If they add to 1, the x+y+z term falls out.

This is where schrodinger's cat. If you wait exactly long enough that the probability of the cat dying is 50%, the cat is exactly equal parts dead and alive. It's accurate, but I think it's confusing because it confuses the fact that quantum states really only apply to very small things, except in isolated cases like this.

Where the unbreakability of quantum encryption comes in is the observer. If you open the box, the cat is no longer both, it's just dead or alive. If you look at the photon, it's A,B, or C. You have destroyed the metainformation contained in the photon, because up until when you observed it, it was x parts A, y parts B, and z parts C.

This is unavoidable and fundamental to quantum mechanics.

For quantum encryption/communication not to work this way, we have to be wrong about quantum mechanics, and the fact that it's just so WEIRD is part of the reason I suspect it will work. It's so counterintuitive people have verified this many times.

Re:I don't know if I can make this clear, but I'll (2, Insightful)

Anonymous Coward | more than 9 years ago | (#11417402)

An observer does not have to be a sentient being. Anything can be an observer, including, other quantum particles.

At any given moment, a quantum particle is having its wave equation collapsed by an interaction with another particle. The key to understanding this is that even though the wave has collapsed, it is not really collapsed and will continue to transmit and collapse.

It is a HUGE misconception that the cat is equally alive or dead, being as those are two fundamentally mutually exclusive properties. At any given point in time, there is a probability that the cat is either alive or dead. The cat interacts with itself (a single quantum particle would not interact with itself and so it cannot collapse its own wave equation) and with the air molecules, box molecules, etc. Whether or not YOU look at the cat or not is irrelevant. The cat interacts with its environment and other particles simply by the means of being.

Once you stop trying to think that an observer must be a sentient being with intent to measure a particle, you can see that the particle itself is interacting with other particles, each acting as observers of the other.

Re:I don't know if I can make this clear, but I'll (1)

iamnotacrook (816556) | more than 9 years ago | (#11417498)

It is a HUGE misconception that the cat is equally alive or dead, being as those are two fundamentally mutually exclusive properties. At any given point in time, there is a probability that the cat is either alive or dead.

You have misconceptions of your own. I dont know your background but you haven't grasped why Schrodingers cat says something very different about the quantum world. You are trying to fit it into a classical viewpoint. (or trolling).

Test, please ignore (0)

Anonymous Coward | more than 9 years ago | (#11417489)

test please ignore

Could it break the "unbreakable" method? (1)

Call Me Black Cloud (616282) | more than 9 years ago | (#11417516)


In my job as a contractor for a government agency, I've had the opportunity to read a lot about the history of crytopgrahy and code breaking. If there's one thing I've learned, it's that one time pads are unbreakable (when properly created and handled). Does quantum computing affect this unbreakability?

Why fix what isn't broken? (0)

Anonymous Coward | more than 9 years ago | (#11417529)

rot26 encryption works just fine for me.

basic principles (0)

Anonymous Coward | more than 9 years ago | (#11417533)

simply, quantum computers dont work on the same principles as our relatively childish PC's. Only the most rudimentary Q/C's exist, or to be more specific, only the most rudimentary quantum processors exist, and thats only in cutting edge labs ala IBM and some very cashed up universities (under extreme temp/pressure/material conditions). so in other words, by the time theses things are available commercialy, 50+ years at best, the quantum entanglement solution to encyption, the infallible solution (excluding an 'insider') may well be viable to use in a Q/C network.

So SMoking Gnu are ahead in optical cracking? (1)

tod_miller (792541) | more than 9 years ago | (#11417544)

Referencing going postal, the semaphor towers would be the 'optical fibre' in discworld they erect a canvas sheeting to block the LOS between two towers, and:

a) send a sequence of messages to jam the machanics (a 'woodpecker' ala a buffer overflow worm)
b) send a creepy posthumous message

I am sure after they spend loads on quantum cryptography, and tell all theit employees that QUANTUM is protecting them, it will be easier than ever to call up and ask for the email they just received over quantum to be faxed to your office, because your 'damned' quantum line is down again.

Oh I forgot: ----spoiler warning----

Right On Time! (1)

Vo0k (760020) | more than 9 years ago | (#11417552)

Finally we can start research stating that P=NP without worry that our discovery would empty our accounts.
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