## What Is Quantum Cryptography?

Every time you buy something online, you put your faith in math simple math that's easy to do in one direction but difficult to do in reverse. Thats what protects your credit card information from would-be thieves. But the system can be hacked. One popular encryption scheme, for instance, can be undone only by factoring a huge random number, a key unlocking encoded information, into two prime numbers. Its a task that today is extraordinarily difficult, but not impossible. With enough computing power, a spying government could break the key. Or some clever mathematician could find an easy way to factor large numbers and do it tomorrow, in theory. In search of greater security from code breakers, a new generation of code makers has been turning from math to physics. Experts in atoms and other particles, these cryptologists want to exploit the laws of quantum mechanics to send messages that are provably unhackable. They are the architects of a new field called quantum cryptography, which has come of age only in the past few decades. Quantum cryptography draws its strength from the weirdness of reality at small scales. The particles making up our universe are inherently uncertain creatures, able to simultaneously exist in more than one place or more than one state of being. They choose how to behave only when they bump into something else or when we measure their properties. Quantum cryptography draws its strength from the weirdness of reality at small scales. The most popular cryptographic application yet for this strange behavior is quantum key distribution, aka QKD. A quantum key encodes and sends the information needed to decrypt a message in the fuzzy properties of particles, typically light particles. Eavesdroppers trying to steal the key must make measurements of th Continue reading >>

## What Is Quantum Cryptography? - Definition From Whatis.com

This email address doesnt appear to be valid. This email address is already registered. Please login . You have exceeded the maximum character limit. Please provide a Corporate E-mail Address. By submitting my Email address I confirm that I have read and accepted the Terms of Use and Declaration of Consent. By submitting your personal information, you agree that TechTarget and its partners may contact you regarding relevant content, products and special offers. You also agree that your personal information may be transferred and processed in the United States, and that you have read and agree to the Terms of Use and the Privacy Policy . Quantum cryptography is different from traditional cryptographic systems in that it relies more on physics, rather than mathematics, as a key aspect of its security model. Essentially, quantum cryptography is based on the usage of individual particles/waves of light ( photon ) and their intrinsic quantum properties to develop an unbreakable cryptosystem - essentially because it is impossible to measure the quantum state of any system without disturbing that system. It is theoretically possible that other particles could be used, but photons offer all the necessary qualities needed, their behavior is comparatively well-understood, and they are the information carriers in optical fiber cables, the most promising medium for extremely high-bandwidth communications. In theory, quantum cryptography works in the following manner (this view is the "classical" model developed by Bennett and Brassard in 1984 - some other models do exist): Assume that two people wish to exchange a message securely, traditionally named Alice and Bob. Alice initiates the message by sending Bob a key , which will be the mode for encrypting the message data. This is a Continue reading >>

## Can Quantum Cryptography Work In The Real World? -- Gcn

Can quantum cryptography work in the real world? Battelle Memorial Institute has built what it claims is the nations first production system for quantum distribution of cryptographic keys and announced plans to create a 400-mile link enabling quantum-key distribution (QKD) between Columbus, Ohio, and Washington, D.C., by 2015. QKD uses a photon's polarization and spin to verify an unobserved key transmission. Read more . The project links two facilities in central Ohio and is a demonstration of the R&D organizations faith in the ability of the emerging technology to future-proof cryptography threatened by increasingly powerful computers. Practical QKD systems have existed for about 10 years, said Don Hayford, director of research at Battelle. But limitations in the range and scalability of the systems have so far restricted their use in this country primarily to research. Although new in the United States, banks and government agencies in Europe have been using QKD for several years. Battelle is using hardware from the Swiss firm ID Quantique to link its headquarters campus in Columbus with a manufacturing facility about 30 miles away in the suburb of Dublin. New tools will be needed to make the technology feasible for anything larger than a metro area, but Hayford is confident Battelle will be able to offer the technology to its customers, including government, in a few years. We certainly will go for FIPS approval, required for government crypto systems, he said, referring to the Federal Information Processing Standards. Not everyone is so sanguine about the current capabilities of QKD. The National Institute of Standards and Technology, which has been doing research on quantum cryptography for years, does not yet feel it is viable for production systems. Its still a Continue reading >>

## What Is Quantum Cryptography? Its No Silver Bullet, But Could Improve Security

What is quantum cryptography? Its no silver bullet, but could improve security In the arms race between white and black hats, the infosec industry looks to quantum cryptography and quantum key distribution (QKD). That may be just part of the answer, however. Use commas to separate multiple email addresses Quantum cryptography, also called quantum encryption, applies principles of quantum mechanics to encrypt messages in a way that it is never read by anyone outside of the intended recipient. It takes advantage of quantums multiple states, coupled with its "no change theory," which means it cannot be unknowingly interrupted. Encryption has been around since the beginning of time, from the Assyrians protecting their trade secret of manufacturing pottery to Germans safeguarding military secrets with Enigma. Today, its under threat more than ever before. That's why some people are looking to quantum cryptography to protect data in the future. Heres how encryption works on traditional computers: Binary digits (0's and 1's) are systematically sent from one place to another, and then deciphered with a symmetric (private) or asymmetric (public) key. Symmetric key ciphers like Advanced Encryption Standard (AES) use the same key for encrypting a message or file, while asymmetric ciphers like RSA use two linked keys private and public. The public key is shared, but the private key is kept secret to decrypt the information. [ Learn which email encryption product will work for you . | Get the latest from CSO by signing up for our newsletters . ] Yet public-key cryptography protocols like Diffie-Hellman, RSA and elliptic-curve cryptography (ECC), which survive on the basis that they rely on large prime numbers that are hard to factor, are increasingly under threat. Many in industry Continue reading >>

## How Quantum Cryptography Works

The NSA affair has once again catapulted the subjects of data security and, more specifically, data exchange into the focus of the media and the public. How do you prevent data from being intercepted by a third party? The solution to this problem lies in cryptography: The message must be encoded. However, this measure also carries some risks. What if the key exchange is intercepted? This is precisely where quantum cryptography comes into play. The fundamental idea behind so-called quantum key distribution (QKD) is to use single photons instead of entire photon bundles. This way an eavesdropper (referred to as Eve in quantum mechanics) cannot simply divert the photons that are sent from Person A to Person B (referred to as Alice and Bob, respectively, in quantum mechanics). Eve would have to copy and then detect the photons to prevent the interception from being detected by Bob. This is precisely what quantum mechanics renders impossible (the so-called no cloning theorem). Figure 1 depicts what key generation for coding and decoding data can look like. This so-called BB84 protocol (developed by Bennett and Brassard in 1984) uses the polarization of photons as a means of generating a key sequence. Alice selects one of four polarization states H (horizontal), V (vertical), +45, and -45 and sends such a photon to Bob. She must first indicate which bit value the two orthogonally arranged polarization states have: 0 or 1. In our example, H corresponds to 0, V corresponds to 1, 45 correspond to 0, and -45 correspond to 1. If Bob receives such a photon, he decides whether to measure based on H/V or 45/-45 and ultimately makes a note of the polarization state (and thus the bit value) of the photon. Bob communicates with Alice in the classic sense, and they compare their base se Continue reading >>

## Quantum Cryptography And The Future Of Security

Quantum cryptography and the future of security Written by BT on 19 November 2018 in Sponsored Article Quantum computers will soon make some of our strongest encryption useless. And that's where quantum cryptography comes in This article originally appeared in Wired . Quantum computers will soon render some of our strongest encryption useless, cracking high-entropy keys in seconds thanks to their ability to quickly work out the long prime numbers used to generate them. If you're wondering what the tech industry is going to do about it, then research, technology and telecommunications experts BT might have the answer. Photons in a quantum superposition state pulse down a fibre-optic cable at BT's Adastral Park research facility, resolving into binary ones and zeros as they reach their destination, where they're read as a key that can decrypt a parallel stream of data. Thanks to quantum indeterminacy, any attempt to snoop on the transmitted keys is immediately detected. This is quantum key distribution (QKD), and it's one method of securely transmitting data without using traditional public key encryption. So far, the QKD encryption system's security seems robust, but it's still experimental, and its first users outside the research community are likely to be those for whom security is far more important than cost or convenience. BT's head of optical research Andrew Lord predicts that early adopters will include "niche players such as secure government, the financial sector, health, cloud and critical infrastructure." QKD could be used to protect major UK network routes and provide quantum-protected Ethernet connections for companies that need high-security communications, including firms in the energy sector and "anyone with an asset that needs protecting that would cau Continue reading >>

## How Quantum Cryptography Works: And By The Way, It's Breakable

How quantum cryptography works: And by the way, it's breakable Quantum cryptography is not infallible. But before getting to how it can be compromised, Michael Kassner calls on some experts to explain how Quantum Key Distribution works. My editor, Selena Frye called, asking what I knew about quantum cryptography. I remember muttering something about qubits. "Good," she said. "This Phys.org article discusses a problem that has been fixed, I'd like you to write about it?" I didn't even know quantum cryptography was broken. And, they already have a fix. The article didn't go into detail as to what's broken, but mentioned that Dr. Hoi-Kwong Lo (at right) and Dr. Vadim Makarov (pictured below) had independently developed ways to compromise quantum encryption systems. That's where I'll start. I contacted both gentlemen, asking for help. Their enthusiasm caught me off-guard, as did the ten papers they sent on quantum cryptography weaknesses and how to fix them. I didn't get very far reading the papers. "This is complicated stuff," I thought, "I better start at the beginning." I asked Dr. Makarov if he had anything that would bring me up to speed. He suggested: Chapter 5. Quantum Cryptography from the book Multidisciplinary Introduction to Information Security . It turned out to be just what I needed. Dr. Makarov also offered the following advice: "Reading original-research articles on quantum cryptography can indeed be hard. I hope you don't want to become a scientist on this topic." Who says quantum cryptographers don't have a sense of humor? My first question is: "Why quantum cryptography?" Why is it better than what we currently have? Dr Makarov had this to say: Quantum cryptography is the only known method for transmitting a secret key over distance that is secure in prin Continue reading >>

## Using Quantum Cryptology | Howstuffworks

Quantum cryptography uses photons to transmit a key. Once the key is transmitted, coding and encoding using the normal secret-key method can take place. But how does a photon become a key? How do you attach information to a photon's spin? This is where binary code comes into play. Each type of a photon's spin represents one piece of information -- usually a 1 or a 0, for binary code. This code uses strings of 1s and 0s to create a coherent message. For example, 11100100110 could correspond with h-e-l-l-o. So a binary code can be assigned to each photon -- for example, a photon that has a vertical spin ( | ) can be assigned a 1. Alice can send her photons through randomly chosen filters and record the polarization of each photon. She will then know what photon polarizations Bob should receive. When Alice sends Bob her photons using an LED , she'll randomly polarize them through either the X or the + filters, so that each polarized photon has one of four possible states: (|), (--), (/) or ( ) [source: Vittorio ]. As Bob receives these photons, he decides whether to measure each with either his + or X filter -- he can't use both filters together. Keep in mind, Bob has no idea what filter to use for each photon, he's guessing for each one. After the entire transmission, Bob and Alice have a non-encrypted discussion about the transmission. The reason this conversation can be public is because of the way it's carried out. Bob calls Alice and tells her which filter he used for each photon, and she tells him whether it was the correct or incorrect filter to use. Their conversation may sound a little like this: Since Bob isn't saying what his measurements are -- only the type of filter he used -- a third party listening in on their conversation can't determine what the actual p Continue reading >>

## Quantum Cryptography

This introductory section possibly contains original research . Please improve it by verifying the claims made and adding inline citations . Statements consisting only of original research should be removed. ( Learn how and when to remove this template message ) Quantum cryptography is the science of exploiting quantum mechanical properties to perform cryptographic tasks. The best known example of quantum cryptography is quantum key distribution which offers an information-theoretically secure solution to the key exchange problem. Except for post-quantum cryptography (see below), as of 2017, currently used popular public-key encryption and signature schemes (e.g., elliptic-curve cryptography (ECC) and RSA ) can be broken by quantum adversaries.[ citation needed ] The advantage of quantum cryptography lies in the fact that it allows the completion of various cryptographic tasks that are proven or conjectured to be impossible using only classical (i.e. non-quantum) communication (see below for examples). For example, it is impossible to copy data encoded in a quantum state and the very act of reading data encoded in a quantum state changes the state . This is used[ citation needed ] to detect eavesdropping in quantum key distribution. Quantum cryptography uses Heisenberg's uncertainty principle [1] formulated in 1927, and the no-cloning theorem [2] first articulated by Wootters and Zurek and Dieks in 1982. Werner Heisenberg discovered one of the fundamental principles of quantum mechanics: "At the instant at which the position of the electron is known, its momentum therefore can be known only up to magnitudes which correspond to that discontinuous change; thus, the more precisely the position is determined, the less precisely the momentum is known, and conversely [3] (He Continue reading >>

## Understanding Quantum Cryptography

Sign in or register to rate this publication Quantum cryptography uses physics to develop a cryptosystem completely secure against being compromised without knowledge of the sender or the receiver of the messages. The word quantum itself refers to the most fundamental behavior of the smallest particles of matter and energy. Quantum cryptography is different from traditional cryptographic systems in that it relies more on physics, rather than mathematics, as a key aspect of its security model. Essentially, quantum cryptography is based on the usage of individual particles/waves of light (photon) and their intrinsic quantum properties to develop an unbreakable cryptosystem (because it is impossible to measure the quantum state of any system without disturbing that system.) Quantum cryptography uses photons to transmit a key. Once the key is transmitted, coding and encoding using the normal secret-key method can take place. But how does a photon become a key? How do you attach information to a photons spin? This is where binary code comes into play. Each type of a photons spin represents one piece of information -usually a 1 or a 0, for binary code. This code uses strings of ones and zeros to create a coherent message. For example, 11100100110 could correspond with h-e-l-l-o. So a binary code can be assigned to each photon, for example, a photon that has a vertical spin ( | ) can be assigned a 1. If you build it correctly, no hacker can hack the system. The question is what it means to build it correctly Renato Renner, the Institute of Theoretical Physics in Zurich. Regular, non-quantum encryption can work in a variety of ways but generally a message is scrambled and can only be unscrambled using a secret key. The trick is to make sure that whomever youre trying to hide y Continue reading >>

## Laws Of Physics Say Quantum Cryptography Is Unhackable. It's Not

Laws of Physics Say Quantum Cryptography Is Unhackable. It's Not Laws of Physics Say Quantum Cryptography Is Unhackable. It's Not Laws of Physics Say Quantum Cryptography Is Unhackable. It's Not In the never-ending arms race between secret-keepers and code-breakers, the laws of quantum mechanics seemed to have the potential to give secret-keepers the upper hand. A technique called quantum cryptography can, in principle, allow you to encrypt a message in such a way that it would never be read by anyone whose eyes it isnt for. Enter cold, hard reality. In recent years, methods that were once thought to be fundamentally unbreakable have been shown to be anything but. Because of machine errors and other quirks, even quantum cryptography has its limits. If you build it correctly, no hacker can hack the system. The question is what it means to build it correctly, said physicist Renato Renner from the Institute of Theoretical Physics in Zurich, who will present a talk on calculating the failure rate of different quantum cryptography systems at the 2013 Conference on Lasers and Electro-Optics in San Jose, California on June 11. Regular, non-quantum encryption can work in a variety of ways but generally a message is scrambled and can only be unscrambled using a secret key. The trick is to make sure that whomever youre trying to hide your communication from doesnt get their hands on your secret key. Cracking the private key in a modern crypto system would generally require figuring out the factors of a number that is the product of two insanely huge prime numbers . The numbers are chosen to be so large that, with the given processing power of computers, it would take longer than the lifetime of the universe for an algorithm to factor their product. But such encryption techniques Continue reading >>

## Quantum Cryptography And The Future Of Security

Quantum cryptography and the future of security Quantum computers will soon make some of our strongest encryption useless. And that's where quantum cryptography comes in Quantum computers will soon render some of our strongest encryption useless, cracking high-entropy keys in seconds thanks to their ability to quickly work out the long prime numbers used to generate them. If you're wondering what the tech industry is going to do about it, then research, technology and telecommunications experts BT might have the answer. Photons in a quantum superposition state pulse down a fibre-optic cable at BT's Adastral Park research facility, resolving into binary ones and zeros as they reach their destination, where they're read as a key that can decrypt a parallel stream of data. Thanks to quantum indeterminacy, any attempt to snoop on the transmitted keys is immediately detected. This is quantum key distribution (QKD), and it's one method of securely transmitting data without using traditional public key encryption. Corporate innovation? Its pointless without partners So far, the QKD encryption system's security seems robust, but it's still experimental, and its first users outside the research community are likely to be those for whom security is far more important than cost or convenience. BT's head of optical research Andrew Lord predicts that early adopters will include "niche players such as secure government, the financial sector, health, cloud and critical infrastructure." QKD could be used to protect major UK network routes and provide quantum-protected Ethernet connections for companies that need high-security communications, including firms in the energy sector and "anyone with an asset that needs protecting that would cause a lot of damage if it were in the wrong han Continue reading >>

## How Quantum Key Distribution Works -- Gcn

Quantum key distribution (QKD) uses individual photons for the exchange of cryptographic key data between two users, where each photon represents a single bit of data. The value of the bit, a 1 or a 0, is determined by states of the photon such as polarization or spin. Can quantum cryptography work in the real world? Battelle has implemented the first quantum-key distribution system for production use in the United States, but NIST researchers remain skeptical about moving it from the lab to large-scale use. Read more . At the senders end, a laser generates a series of single photons, each in one of two polarizations: horizontal or vertical. The polarization of the photon is measured at the receivers end. If an eavesdropper intercepts the photon to determine its polarization, the photon is destroyed in the process, and the eavesdropper would have to generate a new, duplicate photon to pass on to the receiver. Thats fine, as long as there is only a single property or state being sent, said Don Hayford, director of research at Battelle Memorial Institute, which has implemented a QKD system at its Columbus, Ohio, headquarters. But a second state, such as spin, is also part of the photon. The uncertainty principle of quantum physics makes it impossible for the eavesdropper to determine both properties of the photon, so it would be impossible for him to send along an accurate duplicate. Because of this, the receiver would notice a high error rate in the photons being received, which would indicate someone was intercepting the data. To determine the error rate, the states of a small percentage of photons are compared over a separate channel by the receiver and the sender. Because the comparison process destroys the photons these cannot be used in creating a key. But the erro Continue reading >>

## How Does Quantum Encryption Work?

There has been a lot of buzz about quantum computing especially with D-Wave breaking the limits each month. I have basic knowledge about cryptography with an introductory course in quantum computing. So, how does quantum encryption work? and how is it different in principle from the current practices adopted? This article is from a security conference presentation that covers both QC and QKD. arxiv.org/abs/1609.09157 floorcat Jan 27 '17 at 20:27 This is what you hear all the buzzing about. Specifically there is something called Shor's algorithm , that when used to break modern crypto, can be devastating. If you've encrypted a zipfile and told someone the key you're quite safe. But things like PGP and SSL, where you have to agree to a key online, are vulnerable; quantum algorithms have about an impact of O(n/2) on symmetric crypto decrease the effective key size by half for symmetric crypto. That means AES-256 will be as strong as a pre-quantum AES-128. RSA will be much worse off: Shors Algorithm, which can only be executed on a quantum computer, can factor large numbers in $\log(n)^3$ time, which is drastically better than the best classical attack. [Normally RSA2048] takes about $10^{41}$ units of time ... Using Shors algorithm, the same problem only $10^3$ This is not something D-Wave can do yet. As far as we know. Geordie (chief technology officer of D-Wave) on June 2, 2011 at 3:59 pm said: We do have a factoring algorithm that Im going to do a series of blog posts on (the working title is Better than Shor :-) ). After that they never mentioned this again. Either he was wrong or someone told him to shut up about it. This is what the other answer mentions, and this is something we can do today, and because of that there's some hype about it. What it comes down to is Continue reading >>

## Qkd - How Quantum Cryptography Key Distribution Works

Valter Popeskic Scientific & Academic , Security No Comments QKD Quantum key distribution is the magic part of quantum cryptography. Every other part of this new cryptography mechanism remains thesame as in standard cryptography techniques currently used. By using quantum particles which behave under rules of quantum mechanics, keys can be generated and distributedto receiver side in completely safe way. Quantum mechanics principle, which describes the base rule protecting the exchange of keys, is Heisenbergs Uncertainty Principle. Heisenbergs Uncertainty Principle states that it is impossible to measurebothspeed and current position of quantumparticles atthe same time. It furthermore states that the state of observed particle will change if and when measured. This fairly negative axiom which says that measurement couldnt be done without perturbing the system is used in positive way byquantum key distribution. It a real communication system, if somebody tries to intercept photon-powered communication so that it can get the crypto key which is being generated by this photon transfer, itwill need to squeeze transferred photons through its polarization filter to read information encoded on them. As soon as it tries with wrong filter it will send forward the wrong photon. Sender and receiver will notice the disparity in exchanged data and interpret it as detection of interception. They will then restart the process of new crypto key generation. 1) Photon Smallest particle of light is a photon. It has three types of spins: horizontal, vertical and diagonal which can be imagined as right to left polarization. 2) Polarization Polarization is used to polarize a photon. Polarize the photon means to filter the particle through polarization filter in order to filter out unwanted Continue reading >>