Slashdot Mirror
First Bank Transfer via Quantum Cryptography
An anonymous reader writes with today's announcement that "the Austrian project for Quantum Cryptography made the world's first Bank Transfer via Quantum Cryptography Based on Entangled Photons; see also Einstein-Podolski-Rosen Paradoxon." (For more background, see the recent Slashdot post "Quantum Cryptography Leaving the Lab.")
Yes, but... what will I now need to decode my bank statements?
Wouldn't checking if the transfer went through alter your balance? :-P
...I can't observe my checking account balance without lowering it.
So the transaction slip presumably says:
Your transaction number has a 90% probability of being between 8765432 and 8765478.
Have a 75% nice day.
Craig Steffen
http://www.craigsteffen.net
Due to Insufficient Cat.
When in doubt, mod +1 funny and pray
... there has been a bank error in your favour. Collect $200. :)
..but why do we need this?
The biggest hole in security is usually the people operating technology. Ever want something, call up and ask for it.
What does the ability to have uncrackable encryption do to thwart social engineering tactics?
SIGERR: laziness exceeds quota
I'll give you my entangled photons in exchange for chocolate.
"If you think you have things under control, you're not going fast enough." --Mario Andretti
At the University concluded a study which finds quantum cryptography is a lot better than plain cryptography. Please FAX bank account via quantum cryptography to KWEISE MFUME at +34 79 345 8792 for full article.
Looking forward to hearing,
Letter
are only good for small change...
MP3 Search Engine
Thats some damn complicated stuff, there! I hope the technicians who fix the ATM machine know about phuton criptography. I may know how to program with code, but damned if i know how futons work!
http://github.com/gbook/nidb
I'm asking this question again because it came a bit to late to the last discussion I posted it in
.1 photon to reduce the probability of generating a two-photon pulse that could be split and eavesdropped undetectably."
Is quantum crypto provably flawed?
I've seen tons of blurbs stating the the link is "absolutely" secure, but it seems that isn't really the case. (see the bottom of the page.)
What strikes me about all this is the following section:
"each pulse should be attenuated to an average of about
What that says to me is that there is not way to 100% know you're transmitting just one photon.
It sounds like there's no device that is capable of transmitting one and only one photon with 100% reliability. If this is the case, a lot of the arguments about how secure this is are vastly overstated.
In the end QC would be vulnerable to a man-in-the-middle attack by watching for multi-photon emissions.
If this is the case, a lot of the noise surrounding QC could turn out to be hype. (The big plus for quantum crypto is that it's supposedly immune to this.) Is there a quantum physicist in the house?
Life is too short to proofread.
Nah, back to those good ol' electrons.
So then the money has been both transfered and not transfered? That sounds like an argument waiting to happen.
"Have you ever thought about just turning off the TV, sitting down with your kids, and hitting them?"
What I don't understand is why can't you cut the line and put in something like a repeater. When you read a bit, you change that photon, but then you just transmit a clean one with the same value (or maybe even change it to confuse).
-I am an elective eunuch.
Bruce Schneier covered why quantum cryptography doesn't solve any security/secrecy problems in his December 15, 2003 Crypto-Gram.
"It's like defending yourself against an approaching attacker by putting a huge stake in the ground. It's useless to argue about whether the stake should be fifty feet tall or a hundred feet tall, because the attacker is going to go around it. Even quantum cryptography doesn't "solve" all of cryptography: the keys are exchanged with photons, but a conventional mathematical algorithm takes over for the actual encryption."
The reason that the man-in-the-middle attack doesn't work is that by doing so, you introduce two sets of attenuation rather than one. If the message is intercepted and then re-transmitted, the message has now been sent through the attenuation cycle twice. This means that instead of the signal being modified by the original attenuation function, it's modified by the attenuation function squared, which is easy to distinguish.
Craig Steffen
http://www.craigsteffen.net
Yeah, but filling out the slip for "1/sqrt(2) |deposit> - i/sqrt(2) |withdrawal>" is a pain, and thanks to the epoch of inflation my balance is now much smaller than the rest of the universe... luckily, even in an income vacuum my balance randomly jumps up, but only for REEEEAAALLLLYY short lengths of time. I've been hawking radiation for a while but everyone says it's just a two slit operation.
Okay, I'm done now.
[TMB]
Yes and no. (Well, we *are* talking quantum stuff here, aren't we?) Do a google for "bell inequality" and see if you can get anything from the results. Basically, the answer is , yes, it is instantaneous. And no, it doesn't violate the speed-of-light limitation because you cannot get any useful information transmitted that way. You see, there are two photons which are interlocked. The first photn came at the speed of light and it contains the information you are looking for. The second photon, which serves to validate the quantum key is redundant from the information point of view, it doesn't carry the bank account balance, it only serves to detect tampering in the system.
I remember reading a book all about the history of cryptography. It outlined the evolution of cryptograpy from simple albhabet substitutions to the concept of quantum cryptography. It shows all the pros and cons and weighs them against eachother.
Excelent read for anyone interested in the field or just currious about it.
ISBN: 0385495315
As I understand it (according to Bill Bryson's "A Short History of Nearly Everything") entangelment does in fact violate Einsteins theory. It says that two entangled photons at any distance apart from each other will react identically instantaneously. **Notice** Instantaneously! That is faster than the speed of light. Einstein did not believe that this was possible, but experiments have shown this to be true, at least as we understand it. The part that impresses me the most is that someone devised a logic experiment that could determine the results with near certainty without altering the results. An excellent source for more information is the book "Mind at Light Speed", I forget the author's name. "A Short History of Nearly Everything" is also a great book which covers so many topics that it made my head spin.
Why doesn't anything interesting happen when I have mod points?
First, Schneier really loves his stake-in-the-ground idea. He used it to describe cryptography in general in his "Secrets and Lies" book (which, IMHO, doesn't hold a candle to the quality of his applied crypto books. In fact, it feels more like a book-long commercial for his managed security business)
Anyway, sure. QC alone ain't gonna help you. But if it's a stake in a ground that's part of a fence, it damn well matters if it's 100 ft tall vs 1 ft tall, or even 10 ft tall.
Does it 'solve' security problems? No, of course not, because as many many many people have already said, in this post and in many other places, the way to defeat the best crypto in the world is to look under a keyboard and copy down the relevant password/phrase that the user wrote on a sticky-note there. (or other social engineering tricks)
It does make security easier, as it prevents MITM attacks, requires (for now) specialized hardware, and provides really-tough-to-decode crypto. So, if you have the rest of your process working, yes, QC can help by being a more secure technology.
But think of the inverse. OK, so, crypto is like a stake in the ground, it doesn't matter what size or where it is. So, let's all use DES, because it's an established standard!
You are only as secure as your weakest link, obviously. You'd be stupid if crypto turns out to be your weakest link, as even not counting QC, there's lots of good, secure crypto processes available.
Returned Peace Corps IT Volunteer
After spending an hour in the wikepedia I have concluded that this is all just hype. Quantum Cryptography is still only theoretically encrypted. It has not been proven yet because quantum mechanics is not fully understood yet.
Furthermore, this is really just a Quantum Key exchange. So tack on whatever protocol you wish to use once you have the key. Quantum encryption is something that would require quantum computing first.
Also please note, the quantum transmission is not even "secure." Its just that if anyone but you reads it, you are secure in the knowledge that you will know about it.
At least this is what I have understood. Still hype. Notwithstanding, as science this is probably an advancement. Its just not what its being marketed as.
Don't look to closely at your account balances, lest they become more uncertain.
This principle is generally true in classical economic transfers as well: Bill Gates keeps having lots of money, but I only sometimes have money; I know I owe lots of money to my bank for student loans, but I only have a suspicion that my friend owes me 50 cents.
Erik
YOU ARE SAYING IMPUDENCE TO ME! THAT IS IMPUDENCE!
It will be cool one day, imagining that for a brief moment, the photons, being in a superposition of states, *could* be transferring all the known wealth of the universe to my bank account. Sadly, when observed, minus service fees, it's probably only like a buck-fifty.
Anybody want a peanut?
Yes, Quantum Cryptographic Communications (QCC) can help with the requirement that the one-time pad must be transmitted in private. However the one-time pad cannot be reused so your key must be the same size as your text. Thus far, Quantum Cryptographic Communications is not a speedy high bandwidth form of communication. It might be OK to transmit a small key but to date it is not OK for sending, in a reasonable period of time, huge one-time pad keys that are as big as your original message.
Another thing people sometimes gloss over about Vernam one-time pads is that your cipher is only as good as your random number generator! If you generate your one-time pad using the v7 libc rand(3) function your one-time pad is next to useless.
Another important aspect of Quantum Cryptography (Quantum Cryptography is not simply limited to communications) is random number generation. Quantum Cryptographic Random Number Generation (QCRNG) is a useful tool in generating keys (one-time pads, block cypher keys, public/private key pairs, etc.).
The importance of QCRNG goes beyond Vernam one-time pads. You want a cryptographically strong RNG such as a QCRNG when you generate your session keys. Sending predictable keys over a QCC protected link is next to useless!
Now IF you have:
then you will begin to approach the ''unbreakable cypher level'' that some people think you get with Vernam One-Time Pad Ciphers.
chongo (was here)
OK, I am not a believer in quantum cryptography for one big reason -- fiber loss. Someone please enlighten me if I'm wrong.
The loss of standard single-mode fiber is about 0.1-0.2 dB/km. Therefore, unless the distance is short (as in this demonstration), the transmitter must send multiple photons to ensure a decent probability of providing the receiver with one photon.
For example, if the span is 100 km long (20 dB loss), then on average only 1 out of every 100 transmitted photons will reach the receiver.
The situation is worse for autocompensating quantum-crypto systems (e.g., polarization-based encoding), because the photons must survive a round trip through the fiber.
Therefore, the relatively high power at the transmitter implies that an attacker can tap into the fiber near the transmitter, subtract (on average) only 1 photon, and remain undetected by the receiver.
Furthermore, typical optical amplifiers add noise (3 dB noise figure for your standard erbium-doped amplifier). The added noise photons would screw up the link, so amplifiers are out.
In the end, it seems to me that quantum crypto is good for table-top demos, and maybe for short jaunts across a metro area. But it is NOT absolutely perfect, at which point computationally difficult encryption is more attractive.
You're missing the point here... Quantum cryptography _creates_ a set of 1 time pads that both the sender and receiver have. So, a fairly small one-time pad is generated, and then the data is encoded & transmitted over a fast line. This is why it's often referred to as QKD (quantum key distribution). For absolute security, you only send data encrypted directly with your key, which is slow, but can't be decoded by a 3rd party.