Tuesday, November 08, 2005

New Quantum Cryptography Speed Record

This isn't a recent article (it was written in 2004) but it gives an idea of how while QC is only in its early stages, it is rapidly growing in technology.

Physicists from the National Institute of Standards and Technology (NIST) have established a world's speed record for 'unbreakable' encryption with their cryptographic system based on the transmission of single photons. With this kind of method, messages cannot be intercepted without detection, meaning transmission is always safe. The NIST "quantum key distribution" (QKD) system was used between two buildings located 730 meters apart for transmitting a stream of photons at a rate of 1 million bits per second. This might not look very fast, but it's 100 times faster than with previous quantum distribution systems.

Monday, November 07, 2005

QC and Security

After the research we have done, I find the most interesting part of QC is the way it employs these theoretical ideas and applies them in such a practical way. We know from our work at the beginning of the semester about Shrodinger's Cat. This is the idea that the mere observation of an event can change its very characteristics. Quantum Cryptography employs this in a very practical manner. If a party sends a packet of information (photons in this case) to another party, the receiving party will know whether that packet of information has been observed if its characterstics have changed.
This article goes into a bit more detail.

Nature reports that on the 21st of April, Austrian scientists used quantum cryptography to transfer a US$3,500 donation to their laboratory.The article explains."Quantum cryptography uses the odd properties of quantum particles to create secure keys for encoding and decoding messages.The very act of observing these particles changes their nature, making it easy to detect any eavesdroppers.Anton Zeilinger, a quantum physicist at the University of Vienna, and his team carried out their bank transaction by applying a particularly secure technique that uses a pair of entangled photons to create the key.The properties of these photons depend on each other, even when they are separated by long distances. After entangling the pair, one is sent to the recipient. Upon arrival, both photons are measured by their respective owners. This act of measurement determines the state of the photons, and thus the state of the key.Before measurement, neither photon carries any useful information that could be stolen by a snoop. "This makes data transmission more secure," says Zeilinger."

Another Diagram

Found Here

Some Limitations of Current Quantum Devices

An extract on some of the limitations of current devices as well as the problems which need to be solved in the future.

"The technology behind quantum cryptography exists today. In fact, you can purchase your own quantum cryptography system today from a company called MagiQ for a mere $50,000. The current problem that prevents quantum cryptography from being implemented on a large scale is rooted in the same laws of quantum mechanics that make it an unbreakable cryptosystem in the first place. Eve's detectors alter the polarization of the light waves that Alice and Bob are using to communicate. In reality, many factors besides Eve exist that could alter the polarization of the light waves. Even simple physical occurrences like water vapor in the air could alter the polarizations. For this reason, it is very difficult to transmit the light over long distances. A year and a half ago, MagiQ announced that its commercially available quantum cryptosystem could transmit messages "an unprecedented 120 km distance." That's a far cry from the many thousands of miles that would need to be traversed between, say, Washington DC and Moscow. Over distances that long, the curvature of the earth becomes a limiting factor. Currently, a straight path is required to limit unwanted changes in polarization.

An even more severe restriction on the power of quantum cryptography also arises from the need to eliminate unwanted changes in polarization. All of the quantum cryptography systems in existence today require a direct connection between two machines in order to transmit data. This is because there is no currently known way to develop "quantum routers" or "quantum gateways" analogous to the routers and gateways of the Internet. The act of routing a polarized light wave from one line to another would alter its polarization. For this reason, quantum encryption might never come into personal use - there is no way that one person's home computer could be directly connected to every Internet server that the person could ever be interested in. Commerce over the Internet may continue to be based on RSA and similar cryptosystems far into the future, even if or when a quantum computer was built to crack RSA. Quantum cryptography might become a tool solely of governments and large banking institutions."


Commercial Cryptography Developments

The following are links to two companies which are at the forefront of developing quantum cryptography. They already have some very interesting products available.



Compact Long Distance Quantum Cryptography

This is a link to a poster about the implementation of quantum cryptography to provide secure communication between two parties over 23km. It has an excellent graphical explanation.


Another Quantum breakthrough

In may of 2005 scientists managed to create a laser that was capable of firing single photons at a time. This is a significant breakthrough for quantum cryptography as before this scientists simply reduced their lasers intensity to a level that gave a high probability that one one photon was emitted. This still left a finite possibility that two photons may be emitted on of which could be intercepted by a would be hacker without the recipients knowledge. The creation of a laser that can fire only single photons removes this security venerability to quantum cryptography. There is a link to the article below.

Link To Article Here

Successful Key Generation

The following link is to an article showing the progress being made in developing key generation techniques. NEC and it's partners were able to continuously generate quantum keys along a 16km cable for two weeks at 13kbps.


Saturday, November 05, 2005

Importance of Quantum Cryptography

I found an article which i believe gives an idea about how important it is to develop methods of quantum cryptograpghy. In terms of security from the material i have read, quantum computers will be a huge threat. They will be able to easily break traditional codes. The group in this article have recognised to possibilities and risks in these areas and have developed a 'directory' of key players in order to research and implement quantum methods of cryptography.

Behind the scenes, cryptographic technologies underpin a great deal of the security that we take for granted. Yet with ever more powerful computers, the encryption and decryption methods that underpin secure communications are under threat. IST researchers are identifying new ways of shoring up defences through advanced quantum computing.

Since Moore's law predicts the doubling of transistor density every 18 months it will become increasingly easy to break cryptographic keys as computational power doubles. For example, the 512 bit RSA public-key cryptosystem developed in 1977, can be broken by university research groups within a few months. Even though keys of 2048 bits are considered by many to be secure for decades, if the huge processing power of futuristic quantum computers can be implemented, then most public key cryptography will become history.


In-Depth Article

Hey guys,
I've found a really detailed article about Quantum Cryptography here.
It talks about the origin of quantum cryptography, and even goes into some detail about the idea of quantum mechanics itself. It is a change from the other websites because it goes into very specific and highly technical language about how QC actually works. It's interesting to see equations that we've actually used (such as Hamiltonian operators) at work here in a practical application.
It also goes into limitations of QC, these include the fact that QC cannot be used over large distances.
It's a pretty long article but I think reading it gives an appreciation of how the theoretical work we've been doing this semester has been applied in a very practical manner.

Thursday, November 03, 2005

Quantum cryptography network gets wireless link

Below is an extract from an article on the first implementation of a wireless link. It was added into Darpa's network of quantum encrypted networks.

"The world's first quantum encryption computer network has been expanded to include a wireless link that uses quantum communications codes.

The wireless connection was added to the DARPA Quantum Network, a quantum fibre-optic network buried beneath the ground in Massachusetts, US. The network was built by US company BBN Technologies with funding from the US Defense Advanced Research Projects Agency (DARPA). It now links 10 different sites, including BBN's offices, Harvard University and Boston University.

The wireless connection was installed by UK defence research company QinetiQ. Brian Lowans, at QinetiQ says introducing the wireless link represents a "critical first step toward global networks protected by quantum cryptography"".

Extract from Here

Wednesday, November 02, 2005

First quantum cryptography network

The article extract posted below is from new scientist. It is from 04 June 2004 Issue. It is a news article describing the launch of the first computer network secured by quantum cryprography. This is a significant event as it shows the the technology is feasible although it still requires a lot of work before it will be widely used. In the post above a similar article described DARPA's current quantum network.

This article can be found HERE.

"The first computer network in which communication is secured with quantum cryptography is up and running in Cambridge, Massachusetts.

Chip Elliott, leader of the quantum engineering team at BBN Technologies in Cambridge, sent the first packets of data across the Quantum Net (Qnet) on Thursday. The project is funded by the Pentagon's Defense Advanced Research Projects Agency.

Currently the network only consists of six servers, but they can be integrated with regular servers and clients on the internet. Qnet's creators say the implementation of more nodes in banks and credit card companies could make exchanging sensitive data over the internet more secure than it is with current cryptography systems.

The data in Qnet flows through ordinary fibre optic cables and stretches the 10 kilometres from BBN to Harvard University. It is encrypted using keys determined by the exchange of a series of single, polarised photons.

Reference: 4 June 2004, Celeste Biever, New Scientist.

Tuesday, November 01, 2005

What is wrong with classical cryptography

This is a fairly simplistic article on the shortcomings of classical cryptography. Click on this link to read the article.

Monday, October 31, 2005

Cryptography Demo

The following is a link to an interactive demonstration of how a particular quantum cryptography algorithm works. It does not go into much depth about the actual algorithm, however it does allow the user to change the parameters and gives a good general idea about how the process works.


Saturday, October 29, 2005

Conventional Methods - Public and Private Keys

Traditionallly in cryptography, the sender and the reciever of the message know and use the same secret key. The sender uses the key to encrypt the message and the reciever uses the same key to dycrypt the message.

"The main challenge is getting the sender and receiver to agree on the secret key without anyone else finding out. If they are in separate physical locations, they must trust a courier, a phone system, or some other transmission medium to prevent the disclosure of the secret key. Anyone who overhears or intercepts the key in transit can later read, modify, and forge all messages encrypted or authenticated using that key."
The generation, storage and management of these secret keys is reffered to as 'key management'. One of the major problems with this form of cryptography is ensuring the key remains secret, especially in open systems with a large number of users.

In order to solve this problem in 1976 public key encryption was introduced.

"each person gets a pair of keys, one called the public key and the other called the private key. The public key is published, while the private key is kept secret. The need for the sender and receiver to share secret information is eliminated; all communications involve only public keys, and no private key is ever transmitted or shared. In this system, it is no longer necessary to trust the security of some means of communications. The only requirement is that public keys be associated with their users in a trusted (authenticated) manner(for instance, in a trusted directory). Anyone can send a confidential message by just using public information, but the message can only be decrypted with a private key, which is in the sole possession of the intended recipient.Furthermore, public-key cryptography can be used not only for privacy(encryption), but also for authentication (digital signatures) and other various techniques.

In a public-key cryptosystem, the private key is always linked mathematically to the public key. Therefore, it is always possible to attack a public-key system by deriving the private key from the public key. Typically,the defense against this is to make the problem of deriving the private key from the public key as difficult as possible. For instance, some public-key cryptosystems are designed such that deriving the private key from the public key requires the attacker to factor a large number, it this case it is computationally infeasible to perform the derivation. "

From this we can see that the implementation of quantum cryptography would be a major breakthrough! It would slove many of the problems currenttly associated with crytpography by allowing secret keys to be sent between users without the possibility of interception.



Thursday, October 27, 2005

Another Introduction

"Quantum cryptography is an effort to allow two users of a common communication channel to create a body of shared and secret information. This information, which generally takes the form of a random string of bits, can then be used as a conventional secret key for secure communication. It is useful to assume that the communicating parties initially share a small amount of secret information, which is used up and then renewed in the exchange process, but even without this assumption exchanges are possible".
This is just another introduction to go with the others. It is a pretty good article although not too indepth. The full article can be located here.

Wednesday, October 26, 2005

Interesting Graphical Explanation

Quantum Cryptography
  1. Alice needs to generate an encryption key to send Bob a secure e-mail
  2. Her photon generator spits out photons of light, each with a random polarization—horizontal, vertical, or diagonal in one of two directions—representing the key
  3. Alice's and Bob's systems agree on the value of each polarization—either a 1 or a 0
  4. Bob receives the secure e-mail and measures the key's polarizations, changing some of them in the process
  5. Bob sends the results to Alice, whose device tells Bob's system which photons were measured correctly. The others are thrown out
  6. Bob figures out the encryption key and decrypts the e-mail
  7. If Eve tries to eavesdrop, she changes the polarizations of some of the photons but isn't sure which ones she's changed.

see: http://www.pcmag.com/image_popup/0,1735,s=25301&iid=25427,00.asp01&iid=25427,00.asp

An Introduction To Cryptology!

Cryptology is a science that studies everything that has to do with codes and passwords.
Cryptography's primary objective is data protection. Encryption, in simple terms, is converting data into an "unreadable" form.It provides solutions for four different security areas:
  • Privacy/confidentiality: Ensuring that no one can read the message except the intended receiver.
  • Authentication: The process of proving one's identity.
  • Integrity: Assuring the receiver that the received message has not been altered in any way from the original.
  • Control: A mechanism to prove that the sender really sent this message.
In everyday society, we see many forms of data protection. The most obvious include PIN numbers, Social Security numbers and passwords for such things as email. Everyday, people recognise the need for security and the need for data protection.
Cryptography dates as far back as 1900 BC when a scribe in Egypt first used a derivation of the standard hieroglyphics of the day to communicate. A more familiar example of an historical use of cryptography would be the morse code.
However, with the recent explosion of technology (such as the internet), the vulnerability of personal information has increased. In accordance with this, there is a far greater need for better methods of data encryption. Modern cryptography has lead to complex computer algorithms which have been written to allow for far more secure and protected data. Even for everyday passwords, the algorithms can be highly sophisticated, I've included this link which shows what an algorithm looks like: garykessler.net/library/crypto.html#password.

Quantum cryptography is an effort to allow two users of a common communication channel to create a body of shared and secret information. This information, which generally takes the form of a random string of bits, can then be used as a conventional secret key for secure communication.

The advantage of quantum cryptography over traditional key exchange methods is that the exchange of information can be shown to be secure in a very strong sense, without making assumptions about the intractability of certain mathematical problems. Even when assuming hypothetical eavesdroppers with unlimited computing power, the laws of physics guarantee (probabilistically) that the secret key exchange will be secure.

What is quantum cryptography?

"Scientists are examining quantum cryptography (QC) as a possible alternative to traditional encryption technologies. But how practical is QC outside the laboratory?

Physicists investigating the fundamental processes of the universe may have found the key (pardon the pun) to the future of cryptography. By applying the principles of quantum mechanics--the laws governing how the subatomic universe works--to the needs of cryptography, researchers are finding that the manipulation of light may be the strongest form of encryption devised to date."

I found this introduction in the article at the following link. I think it's a good initial description.


What we are doing...

This is our blog about an area in quantum technology called quantum cryptography. Over the next few weeks we will be posting a range of interesting articles, links, pictures and comments relevant to this topic.