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Ultrasecure Quantum Communications Over Thin Air
SlashDotIDOne writes "Well, given a hundred years at university and a few extra titles to my name, I'd be comfortable trying to summarize the article so don't take what I say at face value. Apparently British and German researchers have found a way to use quantum crypto through the air, thus allowing it to be used to communicate with satellites, etc. A very secure form since you know whether a message was intercepted, rather hard to tamper with ;). Courtesy India times and Google's new news service."
slashdotted before the first comment..
Beware: In C++, your friends can see your privates!
Excellent book for lay-people and crypto-beginners: Review Here
;)
This has been a working theory for years (and the book suggests it had been done across a distance of several hundred meters back then!)
I hate it when people say "wow, we have an unbreakable code now". We find out new things and rubbish old theories about the universe and it's properties all the time, we may have violated the second law of thermodynamics, what's to say this is "unbreakable" - it's only secure so far
Johns: Well, how does it look now? Riddick: Looks clear.
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
Whether they should be allowed?? Whether they're allowed or not has little bearing on what would happen. You look at the US's export restrictions for crypto, asking people outside the US to download the inferior version, they haven't exactly worked wonders have they?
?
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
Who said that this is the big question? This is not the "big question"; it has already been determined that "terrorists" did not and generally dont use crypto for communication, so thats just a lame excuse to keep the tools crippled (see A5).
Organized crime? just because an infinitessimal number of "organized criminals" (just where the hell are the disorganized criminals? [yes yes, GAOL]) might use crypto to secure thier telephones doesnt mean that the vast majority of people should be denied access, or given access only to cripple ware.
But you know this.
These agenda setting questions are pure bad journalism, plain and simple, and simple minded.
ATH0 Bitcoin: 1DnwFLXczVZV8kLJbMYoheUrpqHesjxrSi
Basically, if you can bug the users keystrokes when they type in their password for the crypto system, then that system is toast- similarly if they have a physical token- if you steal that token.
Or you bribe/blackmail the guy; or you use "lead pipe" cryptanalysis- you hit the guy over the head until he tells you his password.
This system looks good; but don't assume that its going to be 100% secure. In the real world it can't be, unless there's no people in the loop, not even designing the system.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"From the article:
;o)
Quantum codes have obvious uses for military and government communications.
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
Ok, it is not as if we have never heard of government-funded terrorism (think Libya for example). And criminals can certainly get their hands on military equipment (at least in the movies.
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.~
If you want more info, check out http://www.qubit.org, it's got some decent tutorials.
You're missing the point. Quantum cryptography had been done before, but only over fibreoptic cables. This is the first time it has been done through air, which opens up lots of new possibilities.
Anyone got a link to the Nature article itself?
:)
From the guff written here, it all seems implausible. Encoding a message in single photons is fine, but I find it hard to believe that you can transmit a stream of photons several miles through the atmosphere without a single one of them being absorbed or scattered (which would look the same as interception). It's just light, after all.
I wish I could remember any physics. Then I could say something about the possibility of "amplifying" a signal in which the symbols are single photons. But I can't, so I won't even try.
Plus, even taking the above on trust, it doesn't sound too hard to disrupt (with, say, a mirror).
Corrections and extra technical info most welcome!
These sigs are more interesting tha
If you're going to create something for the government its inherantly going to fall into the hands of civilians.
Our arguably most complex technology is the atom bomb but every highschool student with half a brain knows the basics of how a nuclear reaction works.
This isnt really a problem for us because regulation of these components is a relatively easy job. Its not like joe-terrorist can go mine his own plutonium or deuterium or uranium (the makings of most nuclear devices) though there are others.
smoke detectors contain valadium etc and as in a previous slashdot artical can be turned into nuclear devices. (remember the kid in his garden shed)
So back to the real point, how do the creators of this technology (read information) keep it secret. After all information wants to be free. Poloticians screw up interns leak data and university professors love to defeat these kind of things.
So if you're going to create it, you better be sure you want every one to have it. Which is incidently for the same reasons that the guy who created the atom bomb(well theory) is quoted as saying (paraphrased) that he never should have created it dispite the good that has come from nuclear energy.
--Editorial-- (well moreso)
I think that this technology should be created etc. But created for the public domain. Security and privacy are what good countrys are founded on. Through corruption and "wont someone please think of the children" we've given up this freedom peice by peice to the governments that represent men with money. (read riaa)
What then is the next logical step? i say declare war on privacy invasion; since the government isnt run for the people any more it must be business that impliments privacy for the people.
quantum state encryption will finally give people the ability to have a discussion in private. Is the fact that joe is cheating on his wife any more important than saddam having an abomb to joe? what if both were found out. with quantum tech this doesnt seem possible YET.
(alright its a spacious argument but blah)
so now that i sound like a madman i await your flames. encryption doesnt make a person a terrorist and good people have a right to privacy. the argument that if you dont have anything to hide you dont need encryption doesnt hold water. ANY information intended for one party should not be received by another.
Well, given a hundred years at university and a few extra titles to my name, I'd be comfortable trying to summarize the article so don't take what I say at face value.
What I'm about to say MAY or MAY NOT be true. fnord
"Everything you know is wrong. (And stupid.)"
Moderation Totals: Wrong=2, Stupid=3, Total=5.
British-government-owned company involved: QinetiQ
Article from The Economist: "Free-space" optics
'"Free-space" optics requires no fibre' (oh, how I love that British English)
Quantum secure key exchange paper: here
I remember reading once that Philip K Dick (writer of Blade Runner, Minority Report) went mad at the end of his life, one of the reasons being that he was convinced that there were zillions of alien transmissions going through the air which were screwing with his mind.
Perhaps he was right. Perhaps taking lots of hard drugs allows you to tune in to alien quantum communications. Sounds like some experimenting needs to be done...
a sincere question from newbie .
From the article:
"Gift a Washing Machine & get Pearl Set Free @ INR 8590"
They obviously don't know that Perl is FREE for most systems.
Follow me
No, I think you mean Hypersecure. Much stronger than Supersecure or Ultrasecure, though there is a SuperHyperUltraSpecialSecure encryption in the works IIRC. For most people just plain secure works fine though.
"Reporting in Thursday's issue of Nature, the British science weekly"
I thought New Scientist was the British science weekly that is published on Thursdays, that's when mine arrives.
I hate it when people say "wow, we have an unbreakable code now"
One time pads are ABSOLUTELY unbreakable...
"I don't know that Atheists should be considered as citizens, nor should they be considered patriots." -George H.W. Bush
Seriously, if you search on slashdot on 'quantum cryptography', I predict you'll find quite an amount of previous stories saying exactly the same.
By the way, a few minutes ago:
--
If code was hard to write, it should be hard to read
As long as you don't leave copies all over the place :)
Has this .com craze really gone bye-bye? Please, say it ain't so.
A very secure form since you know whether a message was intercepted, rather hard to tamper with ;).
I'm not sure how knowing if a message has been intercepted makes it more secure. I can yell to a friend across a crowded room, and when people turn their heads at the sound of my voice, I know my message has been intercepted. Does that make it more secure?
from the article (yes I read it)
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
If we don't let the public use this, everyone we don't want to have it will get it eventually. There wont be a user base to be framiliar with to help the government in finding the weaknesses. It is the same with cryptography software. Those who want it really bad can write their own or violate an EULA. The law abiding public is shut off from protecting their own things when terrorists and organized crime still can.
Help I'm a rock.
because most people still leave backdoors to their computers open.
if i'm not mistaken, this only makes the transfer of quantum encrypted data secure. most of the methods of transferring encrypted today though probably not as secure as this, are more than enough for most needs and purposes.
its frequently the integrity of either the computer sending the data or the computer receiving the data that gets compromised, and that is usually the issue.
its still a positive development nonetheless though.
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
Let me help answer the question. Yes, It should be allowed to enter the commercial domain. Their overprotection of encryption technology is getting old.
-- -- Warning. Do not stare directly at the sun.
This is just another lie the goverment pushes out to have nice physical backdoors to spy at us all !!!
And a quantum link any 3rd party can couple a 2nd quatum link to the primary. This is not noted because this is no measurement. When the receiver makes his measurement the waveform collases and collaspes the 2nd link, too !!! Due to coupling the 3rd party can automatically read out the information on the 1st link then and even knows the time of the measurement event. Sorry, I can't call a system with such a huge flaw secure in any way !!!
It's much better to use real encryption which cannot decoded by physicla tricks.
Owner of a Mensa membership card.
Quantum Crypto is cool and useful, but as far as preventing hacking or spying it doesn't change anything. The best way to hack or spy isn't intercepting satellite signals. It's planting a listening device in their office where a person thinks they can talk securely. Trying to hack into a secure system is easier with social engineering than brute force.
...here, quickly improved it to 0.5 and 1 km, and then 10 km. Don't quite know why Nature thought this particular paper was so revolutionary -- wake me when they get to about 300 km, the minimal bounce-off-satellite trip.
Indeed - a very good description summary of the original (May, 2000) quantum cryptography is described in this Nature news section. The story in point here is similar crpyptography techniques without the physical constraints of a fibre optic line.
The BBC has a more laymans view of things here
Laptop Reviews
At one point they say
"have sent a key for deciphering coded information over a record 14.5 miles of open space between two mountains in Germany"
And then they say
The keys, which use quantum cryptography, were transmitted as photons of light along optical fibres.
So which is it?
Ultrasecure Quantum Communications Over Thin Air
But how thin does my air have to be? I mean, I try to keep my air in shape but it certainly isn't as thin as it used to be. Perhaps if I move to Tibet.
Well at least the communications are ultrasecure - I find that secure just isn't enough.
So, Tony sends a message to George using this method. A third party, let's call him... Saddam... intercepts the message. George and Tony know the message has been seen, but does Saddam know? Since he changed the state of the information packet by intercepting it, I'd say yes.
Saddam therefore has the message information (which may be valuable on its own) and he has confirmation he's been busted. In other words, he knows he's disrupted Tony and George's communications, and he can take that into account when he acts on the info in the message.
Thus Saddam's role becomes one of "message wrecker" rather than "eavesdropper". This can still be quite a pain in the ass, particularly if wrecking messages is easy. After all, it would be particularly annoying to Tony and George to spend lots of their hard-earned money building such a system, and find that Saddam is wrecking every single message.
Am I right in thinking Saddam will be aware he's been busted?
http://www.qinetiq.com/applications/news_room/news _releases/show.asp?ShowID=272.
This has some details of how the team is working and how the experiment is carried out.
There's the promise of a new press release on the record distance very soon; when its available, we'll post the link.
Did you SEE that??? BRITISH & GERMAN! See that??! That's in EUROPE, see that???!!
It may be that one cannot tamper with the codes without leaving behind evidence of this tampering ... but it seems that there may be the potential here for either physical or electro-magnetic interference to destroy signals completely.
... possibly leading to messages taking multiple physical routes simultaneously.
I hope that some kind of redundancy is built in
-- jetlag
Quantum cryptography is still susceptible to a man-in-the-middle attack on the non-quantum channel used to check your quantum bits to be sure that you were eavesdropped on.
Need a Python, C++, Unix, Linux develop
It's doubtful based on the reports that the US will allow such a thing to pass unless they can intercept and read it.
There is the danger of a man in the middle attack here. Quantum cryptography requires the private transmission of the secure data as well as the public transmission of your polarizer (or what not) settings. If the cracker can replace the public transmission with his own, then he can eavesdrop with impunity.
Quantum Crypto in general seems like a good idea, but think about it. The "good guys" know if the "bad guys" have intercepted the message (not just if the message is tampered with, but even if it's observed). So what do the bad guys do? Intercept EVERY message. The good guys no longer know which messages are trustworthy, and which are not. The key here would be the ability to differentiate between "This message was intercepted by the enemy", and "This message was intercepted, decoded and READ by the enemy". This is a level of detection that is (as far as I know) not yet available.
I am alone, yet I also surf the universal backwash of undifferentiated Being, which is LOVE.
what's to say this is "unbreakable" - it's only secure so far ;)
Right,
Even photons must create some gravity. It would be possible to detect them if the detector was sensitive enougth.
Yes, it's very unlikely. The forces would be almost non-existant, and the air around it and the detector itself would probably generate more noise.
But not impossible.
SlashDotIDOne writes "Well, given a hundred years at university and a few extra titles to my name, I'd be comfortable trying to summarize the article so don't take what I say at face value.
Well wake up then. Going 20km horizontally is
equivalent to going several 100kms vertically in
terms of loss. As the atmosphere is only a couple
of kilometres thick when transmitting to a satellite most of the loss occurs over the first few kilometres. Going 20km in free space is a big deal-- although they did do it at highish altitudes (~2km) where the air is thinner and so the losses are less. But still you could put the communications stations in the mountians as well.
Neil
a simple PMT won't work because the photons generated won't be entangled with the source photon. all of quantum information technology relies on quantum entanglement.
in reality, quantum crypto relies not on getting single photons across but looking at expected and actual error rates in transmission. when entanglement is broken (i.e. a beam-splitter, which is what i think you meant by "mirror"), the error rates jump drastically. that's how you know there is someone else in the loop.
i think the news is that it has been done over a record distance (23km) in open space. when i was at los alamos in 1997/1998 they had achieved quantum crypto over about 1km.
Wrong point,
:)
doing it over the air or over a fibre optic cable is uninteresting to the "unbreakable" nature of the encoding scheme. "unbreakable" suggests that we now know everything there is to know, and we can sit back with a huge grin knowing we are safe forever from crackers. I think that's a little premature
Johns: Well, how does it look now? Riddick: Looks clear.
What, may I ask, do lawyers have to do with this? Or do you have a different kind of QC in mind?
Please, no unexplained acronyms.
Even photons must create some gravity. It would be possible to detect them if the detector was sensitive enougth.
You miss the point. The information is not encoded by modulating the frequency or the amplitude of the photons, it's done by manipulating quantum variables that are sensitive to observation. So, when you snoop the data, you change it, and the stream becomes corrupt. Personally, I just don't see how this beats symetric key cryptography where you can communicate the public portion in the clear (e.g. encode it into public transmissions or send out six couriers with the same info, since you don't care if one of them is intercepted).
Just my brain rambling along as usual however could this kind of message be used to help show that life exists on other planets? For example, this form of communication allows you to test if the message was intercepted. this is why the transmission form was invented in the first place. However if you transmit a message to outer space to a fast traveling space probe a really long way away and find the message got intercepted then who did the interception? If the whole world promised not to intercept the message then logically an intelligence somewhere else did it or someone here broke the promise... Failing that, a random reorganisation of atoms happened to fake the interception. Theoretically you could build a cloud of fast traveling probes using this method of communication. You could cover a large area of space in a matter of years and listen and watch for intercepted signals.
Martin Piper
Owner - ReplicaNet and RNLobby
The only problem with your statement is that this technology isn't wireless, its Optical. As far as I'm aware there aren't too many commercial uses for optical, with the exception of stereo systems and computers. This stuff isn't quite ready for commercial use. Also, one of the big things with the quantum keys is that the key is "programmed" to be a certain number once it reaches its location. If it is intercepted before it reaches there, it will change the state of the photon, therefore changing the state of the key and you will not be able to unencrypt the message. Also you'd have to get the message first, which would change the state of the message and change the encryption key to who-knows-what. :)
I'm not too good at this quantum physics stuff, so I may be wrong, if so then please flame with excessive flamage, I will not be offended. But you'd better be correct, with appropriate backup information, of course.
find ~your -name '*base* | xargs chown
if the message is changed if somebody else 'looks' at it, couldnt that be used as a dos attack? keep fscking with the message, no matter how secure it is, if you cant use it then whats the point?
One time pads are ABSOLUTELY unbreakable...
Erm, no they're not. If you get hold of the decrypting pad you can break it, not that much different than stealing a pgp key and passphrase really.
He who defends everything, defends nothing. -- Fredrick The Great
He wrote the book it was based on. Isn't that close enough?
God is real unless declared integer.
Does anyone else think it would be a great addition to Slashdot's stories if they would include a link to the google news search under every headline? I don't think it would be that hard to automate, but it sure would open the door for us users to see a lot of different articles per issue discussed.
~ now you know
Assuming someone doesn't steal the key and you did it correctly, then yes.
But if you didn't do it correctly, or your pad choices aren't truly random, or someone knows some of the plaintext, or half a dozen other things, then a one time pad can be broken with a lot of guesswork.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Philip K Dick didn't write Blade Runner.
Well, he wrote "Do Androids dream of Electric Sheep", which Blade Runner was based on. Happy now?
Can't someone who is just interesting in disrupting communication instead of intercepting them have a field day with this. Isn't that one of the first objectives of war to cut off HQ from the men on the field, etc
Second, they talk about boosting the signal to achieve the ability to transmit to satalites. This would be at the detriment of the security of the key as the greater the signal strength, the more photons it carries, the easier it is to split off a portion of the beam to be read. This of course is still not in any way easy as statistical analysis of the strength of the signal can reveal that it is being split.
Third, the fact that the signals are being bounced of a satilite autmoatically invalidates the security. If it is relayed, the key is stored in non-quantum states which invalidates it's security. The article sais that the signal on fiber optics has to be boosted every 6 miles. That is also garbage. Boosting the signal again invalidates the security. I don't know anywhere that quantum keys are used through signal boosters.
This experiment is notable though. The farthest a quantum key has been transmitted was 32ish km (I believe in germany), over a single fiber-optic cable. This is the first transmission of a quantum key over a signifigant length through atmosphere.
I do security
Symmetric key cryptography is sensitive to brute-force and possibly cryptanalysis - especially if the key is recycled. You also need couriers. If you are going to use couriers - have them at least carry CD-ROMs full of one-time pad data - that isn't any less practical to achieve.
The adavantage of quantum crypto is that it gets rid of the couriers. What if the attacker intercepts all six couriers - possibly by bribing them all. It just takes one more factor out of the equation. Also - the transmission is not susceptible to cryptanalysis or brute force, assuming your key data is truly random. The actual transmission is encrypted by one-time pad - the only way to crack it is to have the key.
And you are right - the basis of quantum physics is that you CANNOT measure the photon properties using any technique at all without altering them. If there is a clever way around this it would mean that the laws of physics as we understand them are quite wrong. Not that this is impossible, but quantum theory has been tested quite thoroughly. There is always that one experiment that could shoot it all down - but nobody has found it yet.
Ok, maybe I'm off in left field, but given that normal atmospheric diffusion of the beams doesn't count as observation, whats to stop someone eavesdropping the beam scatter and side blead at a greater distance than the receiver (and thus, temporally after they have received and decoded the signal)? The only idea I've got is that it somehow requires >50% of the full beam to get an uncorrupted reading, but that doesn't jibe with them using amplification at both ends (or am I missreading the article?) as that implies that their receiver doesn't have enough fidelity to pick it up without amplification. Someone with some idea of the actual basis fro this care to enlighten me (and then explain how, if it can detect observation off of atmospheric scatter, how this doesn't produce FTL comm via selectivly observing and not observing the beam?)
Realities just a bunch of bits.
If someone intercepted every attempt to transmit your one-time pad, you might have a problem, but there are apparently ways around that.
when a message is transmitted it sent in a way that the message cannot be read by more than one receiver. (in theory) This means that the message cannot be eavesdropped upon. It does not mean the message containing the key is encoded.
So what is the key? the key can be a one time randomly generated bunch of numbers, never written down by the sender, and immediately discarded by the receiver. Thus no passwwords.
Some drink at the fountain of knowledge. Others just gargle.
Knowing some of the plaintext will not help you break the one time pad. The only part of the message that you will be able to deduce given that you know some of the plaintext, is that part of the plaintext that you already know.
www.timcoleman.com is a total waste of your time. Never go there.
The big question, though, is whether they should be allowed to enter the commercial domain, where they could be used by organised crime and terrorism to thwart eavesdropping by police.
Yes. True. On a similar note: cars, food and snail-mail are used by organized crime and terrorists for transportation, nourishment, and communications. Imagine how much better and safer the world would be if we didn't give the public access to these things.
-... ---
I'm sure a lot of the people here already know how quantum computers work, or will work, o whatever. ;)
But here is a great article for those who havn't read anything yet.
To think that two countries who were once dedicated to breaking each other's crypto (WWII) have now worked together to create an 'unbreakable' approach is wonderfully ironic. Gotta love the march of time and change...
-Laz
Read "Quantum Psychology".
ttyl
Farrell
fnord
CAN-CON 2019 - Ottawa's only book oriented Science Fiction Convention! October 18-20, Sheraton Hotel, Ottawa, Canada h
After the initial checksum data has been sent, the parties notice that data is being read. So at this point the transmission can stop before the message is sent. Do not pass go, do not collect 200 dollars.
Right... If that's the level we're discussing it on then no... It's not possible to create a code that is able to determine if it is being used by the wrong persons who've somehow gotten hold of the key...
Nor is it possible to create a code that makes it impossible to get hold of the original plaintext on the source computer, or threatening the author to simply tell you what you want to know...
And no... I guess it's impossible to create a code that can guard against dumbass humans using them the wrong way...
"I don't know that Atheists should be considered as citizens, nor should they be considered patriots." -George H.W. Bush
And you are right - the basis of quantum physics is that you CANNOT measure the photon properties using any technique at all without altering them. If there is a clever way around this it would mean that the laws of physics as we understand them are quite wrong.
... quite wrong ... God ... dice..." :-)
:-) FWIW, I think I was on crack, and said "symetric key" when I meant "asymetric key". Obviously, broadcasting your symetric key over public media, as I suggested, would be a very bad thing :-)
Could have been said, circa Newton: "The basis of physics is that time's passage is constant between any two bodies. If there is a clever way around this, it would mean that the laws of physics as we understand them are quite wrong."
Could have been said, circa Einstein: "The basis of relativistic physics is that actions happen independantly and interact through the transfer of energy, which is bounded by C
It's not that Newton was "quite wrong" or that Einstein was "quite wrong", but rather that they were both correct for a certain problem domain. I suspect that the current work on quantum cryptography will fall apart once we get the GUFT nailed down.
Symmetric key cryptography is sensitive to brute-force and possibly cryptanalysis
Everything is susceptable to brute force. Don't buy it? Try to keep a secret, and I will send some brutes over to your house to torture you... Brute force always works
Sending a courier with symetric key data or a one time pad has the disadvantage of being subject to undetectable interception. When you send 6 couriers with the public portion of an asymetric key, any 5 of them can be intercepted, but a) getting the public portion does not allow decryption and b) replacing the courier/key can be detected by comparing all 6 when they arrive. Expand the number of couriers as required.
but I'm no physicist. Here goes:
The article says that it would be difficult to intercept because interception would be easy to detect because the interception would change the state of the photons. Okay. But then it says that since photons are so easy to deflect the reciever would have to send back info about what packets are missing. So couldn't you just intercept a bunch of bits and the reciever would just assume interference. Is this one of those signal-to-noise inference things a la Stephenson's "Cryptonomicon"?
Furthermore, it mentions some absurd length of time to decrypt these messages, but I assume that's with current tech. What about with a quantum computer? Isn't that the sort of thing that they are supposed to excel at?
Just wondering....
Disclaimer: MINAA (Mummy! I'm Not An Animal!)
Getting hold of a solution to a code is on no way "breaking" it. It's using the key. Idiot!
A laser transmitter was set up at the top of the 2,950-metre (9,587-feet) Zugspitze, and sent out pulses to a receiver, a 25- centimetre (10-inch) shop-bought telescope, positioned on line of sight on another peak, the 2,244-metre (7,293) Westlichekarwendespitze.
Obviously they encrypted the locations so readers wouldn't be able to attempt to eavesdrop as easily.
bytesmythe
Hypocrisy is the resin that holds the plywood of society together.
-- Scott Meyer
You could be given THISISAONETIMEPAD and decrypt it into any string the same length, period. You would have to know the whole plaintext (assuming the OTP is random, which it ought to be), in which case decrpyting it wouldn't be helpful, would it?
The bottom line is that known-plaintext doesn't hurt OTP, because you cannot recover any portion of the pad except for the part that reveals the plaintext.
I've been able to successfully thwart this ultra secure mechanism by simply exploiting it's obvious weakness. Read one photon and get detected? No problem, I insert a photon sensor in the path of thel laser beam and catch all the photons and read the information state, just like the real receiver would, quantum-state be dammed!
Then, just like the original transmitting tower, I repackage everything up nicely and send it on it's merry way, to the destination it was intended.
I have a patent pending on my anti-quantum-crypto measures. Cheerio!
>Whether they should be allowed??
Exactly.
You can't create rules to stop rule breakers -- that's what makes them rule breakers. The only people (as always) who will be negatively impacted by such "disallowing" is the average person.
The two groups mentioned: "organized crime", and "terrorists", have almost as much money and power(in some cases, more) as the governments that would be "allowed" to use this technology.
How long before they circumvent the "rules?"
Oh and BTW, its not a function of criminality, its the nature of rules and power. This is the same dynamic that is at work with regard to taxes, investments, world banking, civil rights, the environment, pick your favorite rant.
People only follow rules when they have to, or or when they want to.
Who is more likely to have to?
Who is more likely to want to?
The powerless cannot pass rules to thwart the powerful, they can only make themselves less powerful.
We are agents of the free
Assymetric encryption is vulnerable to number-factoring - a problem which is currently difficult, but is threatened by quantum computers and the possible development of exponentially faster conventional computers.
As far as the laws of physics changing, that is always possible. One advantage of quantum crypto is that it prevents interception. If somebody figures out how to bypass it and divulges the vulnerability, you can stop using it and rest assured that nobody intercepted anything prior to the disclosure (unless the NSA figured it out five years ago and is keeping quiet about it - but they probably employ a lot more mathemeticians than quantum physicists).
However, with asymmetric or symmetric encryption anybody can intercept your communiction. True - they can't read it now, but they can always save it until technology improves. Some secrets are only important for a few weeks or months - like the next querterly report for comnany XYZ. Some secrets are important for a lifetime. In the first case, I wouldn't be too afraid that somebody might break my message using a quantum computer in three years - in the second case I'd be VERY concerned. Suppose it is a government secret being transmitted from embassy to embassy which contains data obtained by espionage on an allied country (such as the British spying on the Americans or vice-versa). That data would be very sensitive for as long as the alliance exists (how long have the USA and the British been friends now?). You don't want it divulged twenty years from now when somebody finds some old messages and pulls out their 10,000,000 processeors running at 100 petahertz pocket calculator and does a "little" math.
Quantum crypto is a completely different approach to safeguarding a secret, and I think that it will be quite valuable for many years to come - or at least until the laws of physics are changed. And once that happens, you can just stop using it and not worry about who has already intercepted your data. The only other method which comes close is the one-time pad - and then only if you are certain the key is protected and transmitted securely.
This would be at the detriment of the security of the key as the greater the signal strength, the more photons it carries, the easier it is to split off a portion of the beam to be read
Isn't the whole point of cryptography that information can be sent freely with only the intended recipient being able to easily decrypt it? And isn't the point of quantum cryptography to guarantee that only the intended recipient can decrypt it?
But what if it is found out that all or some of the relied-on theories on quantum stuff is wrong, and others have been reading it all along?
Table-ized A.I.
Only RSA and related assymetric algorithms are so threatened. Elliptic curve algorithms, for instance, have no known quantum algorithm to solve them. They also require more conventional horsepower per bit to brute force.
Who said there has to be a decrypting pad? :)
No, quantum cryptography ensures that only the intended receiver received the message. Anyone snooping the message would be detected by the receiver (it's complicated to explain, but it has to do with the rotation of the light wave (remember that photons are both particle and wave)). So, you don't send data over a quantum link, you send your temporary key. When both sides have the key (and know that no one else could have sniffed it), they can use regular channels to send the data encrypted with that key.
"Save the whales, feed the hungry, free the mallocs" -- author unknown
IF you don't use the one time pad more than once (hence the name).
One time pads can be broken if someone gets lazy and starts reusing a key.
I think the 'unbreakable' claim comes in that you cannot read the message without knowing the pad. Of course if you already have the key then the message can be decrypted... but that is obvious and it doesn't count as 'breaking' the cipher.
:-).
So the cipher is unbreakable, but the system as a whole may not be, due to passwords written on Post-It notes etc. IANAC, but I think analysis of new encryption methods doesn't concern itself with such possibilities
-- Ed Avis ed@membled.com
I know how the theory goes. But as a black box, the system guarantees that only the intended person (etc.) gets the decrypted data. Someone reading stray photons does not compromise the system as the original poster claimed, but perhaps they were trolling.
Of course, if there is something we don't yet know about quantum mech then perhaps it's not perfectly safe. Also, actually achieving 100% secure communication requires care in implementing the design - you can't put too many photons out there or some of them can be intercepted without tipping off the recipient.
Human genome = 3 billion base pairs = 6 GBit. Windows + Office = 20 Gbit. Which is more impressive?
Also, by poking around the (unprotected) Kurtsiefer's home directory, you can have a lot of images of the experiment, experimenters, and the beautiful surroundings.
My congratulations to Dr. Kurtsiefer for finally getting this difficult experiment to work. He's been trying to finish it for about a couple years, if I recall correctly.
17779 eligible voters in a district, 17779 'vote' as one. This is Russia.
With corporate IT spending continually declining I have a hard time believing that many companies will abandon their thick air installed base for better encryption. Even if they did, they would most certainly wait until a final thin air standard has been ratified, as most of the current vendor implementations are incompatible.
Actually - too many photons isn't a problem. You send a bunch of photons, determine which if any made it there intact without being intercepted, and then select a portion of them to be the key.
Each photon is a single bit - so if one is intercepted but not part of the key it does no damage. And ones which are intercepted would be rejected as becoming part of the key. (Remember, you decide that you have a secure key BEFORE you send the message - so if it looks like somebody is intercepting bits you can decide not to send the message at all. You could even send a bogus message (which would still be indecipherable) to give the impression that a message was sent when it was not.
well... ohkay
"I don't know that Atheists should be considered as citizens, nor should they be considered patriots." -George H.W. Bush
If the one time pad is done correctly, yes, it's unbreakable. I think I said that.
If it's not done correctly, say, the guy used the same pad on two different messages, or the guy isn't using a good random generator, then a known plaintext attack will give you new parts of messages.
Especially if the guy used the same pad twice.
Like I said, if it's done *correctly* then it's unbreakable. But it often is not done correctly.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
I read this like 2 months ago.. old news.
part b is the now proven and more used Heisenberg princepal nothing is ever 100% this could be starting your' computer to "just check email", and for what ever reason your' config files aren't working (assuming use of DHCP and ethernet ).your' hard drive fales etc.
Thirdly given n time and effort almost any security schemes are breakable
On the quantum side the states do no realy overlop nor do particles exist in two places at once, they may behave as though they do because they can travel so they apear to do so and act as though they do, much like a laser beem seems to hit a wall instantly, it's merly the speed of it that makes it seem to do so, and yet all practical, esoteric, emperical, and anecdotal evidence counters what we see.
So to say quantum computers are based on particles superimposing states is false
What's hapening is that a particle is a sphere righ? it's it has no practical interference right? So if course it can spin, bob and do both(corkscrew), and a realy fast corkscrew that can be used as a third option:neither. This is great for siving, but bad for simple naeve inocent things like:aha i'd like to by a sword in quantum fantasy game x, it breaks things very quickly when the sword seller says: neither. the sword seller doesn't have a sword, and doesn't want to get one.
This hole quantum encryption stuff makes cracking a message, or simple making a message, much more secure that's all, because in day to day use it'll also make it much simpler to add a hardware device to you compter that makes the phisical transmition of the private message vastly easier.
and none of you retards gets it.
I kinda feel like a Jackass for this relpy, but the laws of physics never change. Rather, our understanding of them changes via a series of scientific revolutions. Anyways, it may seem a bit nit-picky, but I believe that the difference is truly important and fundamental to how the entire institue of science is viewed and aprroached.
Couldn't agree more - I actually thought about this but was too lazy to reword... I didn't want to have to up my estimate of the impact of /. on work productivity on the poll...
Or something.
So it's good to know that our communications will be secure.
Ummm.... does anybody remember that RFP by the German Army for a non-M$ operating system?
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
I recall reading about a case (I believe during WWII) where "One time pads" were broken.
Some because a "one time" pad was reused (a no-no clearly) - but more because someone (the English I believe) figured out how the one time pads were being generated - which then led to being able to break the code.
The point being that a large number of "one time pads" (i.e. most normal use cases of them) requires some method of generating (and then sharing) the pads - if this method is discovered then it is possible to break them.
-- Join us in Chicago May 1-4th for MeshForum -- writer, historian, tech geek, entrepreneur, internet junky since '91 --
Sigh.
:+5 Insightful.
I can't remember the last time I read about a new idea to improve security on slashdot where not at least one genius explained to us all that "this does not solve the whole problem". Who is really surprised about this ? Then said genius goes on to mention a random set of irrelevant "weaknesses" which really are other parts of the whole security issue, completely irrelevant to the new piece of technology. And then ofcourse, moderators fall in love, and moderate said genius to Score
Completely removing one possible way to break your whole security scheme obviously improves security, and that's all there is to it.
My question is, how do you know that the intended recipient is getting the key, and not someone else?
"Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
A few interesting links for those seeking more technical information:
The original press release from QinetiQ is available at this news release.
Here is the corresponding German press release from the University in Munich.
More interesting, perhaps, is the page of one of the German professors involved in the experiment, devoted to this same subject, found here (in English!).
Philip K Dick didn't write Blade Runner.
Well, he wrote "Do Androids dream of Electric Sheep", which Blade Runner was based on. Happy now?
Nope.
Blade Runner wasn't based on "Do Androids Dream of Electric Sheep?" The MOVIE CALLED "Blade Runner" was based on ""Do Androids Dream of Electric Sheep?"
This is not a silly quibble. Blade Runner was a completely different book (By Alan E. Nourse, if I recall correctly). It's about a future dystopia where medical care is banned (in a misguided attempt to breed out dangerous recessives), except for people who have been sterilized. A very fatal Flu is circulating. There's a vaccine, but because you can't get it unless you volunteer for sterilization you're about to have a situation where all the surviving humans are sterile. One lead character is a "Blade Runner" - a surgical tool bootlegger for an illegal surgeon.
The makers of the movie version of "Do Androids dream of Electric Sheep" blatantly ripped off the name of the unrelated book - apparently because it sounded cool. Nothing in the movie is in any way related to blades or the book with the same title.
So the media empire strikes again, shafting TWO authors for the price of one.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Elliptic curve algorithms, for instance, have no known quantum algorithm to solve them. They also require more conventional horsepower per bit to brute force.
Pay close attention to the word "known" there. Very important word.
And remember that factoring used to require a lot more horsepower per bit than it does now. We've been working on factoring for a lot longer than elliptic curves, but we're catching up. Remember that we don't know the minimum effort required to do either one.
TTFN
Boosting the signal again invalidates the security.
That's true, but a quantum computer could perform error correction on a quantum key exchange because it can perform operations on entangled states without decohering them. I assume that would enable it to serve as a repeater for key exchanges over long distances. I don't know if anyone has demonstrated this, but it's possible in theory with the ~5 qbit computers we currently know how to make.
TTFN
Re " ...I just don't see how this beats symetric key cryptography "
Ummm, make that "asymmetric key". Right?
"Contrariwise," continued Tweedledee, "if it was so, it might be, and
if it were so, it would be; but as it isn't, it ain't. That's logic!"
-- Lewis Carroll, "Through the Looking Glass"
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Try this phrasing: Until the laws of physics are (better understood|clarified). Or: Until our understanding of the universe improves.
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Peter Cordes ; e-mail: X(peter@cordes ,