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Cryptography with Quantum key distribution(QKD)

admin — Sun, 05 Sep 2021 14:22:02 +0000

Quantum is touted as more revolutionary technology than even modern day internet. Quantum computers will provide unparalleled processing power and run billion times faster than any supercomputer ever made. The principles of nature and quantum physics will enable quantum computers to bring the expected revolution to the world in a decade or two. However, there are good and not so good uses of any technology and quantum is no different. The same advantages, for instance, can enable breaking of security at any level of cyber infrastructure. Quantum computers bring major challenges to cyber security and need to develop mechanisms to counter the threat. In this article, Quantum Guru touches upon the highly decorated Quantum Key Distribution to help alleviate the risk.

What are the cybersecurity risks to current cryptographic techniques?

Current cybersecurity infrastructure mandates following two functions:

Authentication – Allows distant users to trust their counterpart and validate the content of their exchanges. Public key scheme is used to implement authentication
Confidentiality – Allows (and is required for) exchange of any private information between distant users. It is executed in a two-step process and users have to share a secret key at the start. It uses the public-key protocol, commonly known as the key exchange mechanism. The secret key is used in a symmetric key encryption scheme.

Therefore, both functions depend on similar cryptographic techniques, known as asymmetric or public-key cryptography as shown in Figure 1.

However, cybersecurity is much more than the underlying cryptography. All current hacks and security failures do not come from weak cryptography, but rather from faulty implementation, social engineering, to name a few. Current systems trust the cryptography and fight to get the implementation right.

Unfortunately, things are about to change with the advent of quantum computers. Today the point of cryptographic vulnerability is public-key cryptography that is implemented using algorithms such as RSA. These are used both to authenticate data and to securely exchange data encryption keys.

The processing power of the quantum computer can solve these mathematical problems exponentially faster than classical computers and break public-key cryptography. As a result, the currently used public-key cryptosystems are not appropriate to secure data that require long-term confidentiality. An adversary could indeed record encrypted data and wait until a quantum computer is available to decrypt it, by attacking the public keys.

What is Quantum Key Distribution (QKD)?

The concept of QKD was first proposed in 1970’s. QKD is the only provable secure communication method because it uses physics, not math to encrypt data. QKD also known as Quantum Cryptography is a technology that uses quantum physics aimed to secure the distribution of symmetric encryption keys. QKD is the technology that can address a long-term confidentiality issue of secured data.

How does QKD improve traditional cryptography implementations?

A security solution is as secure as its weakest link and in network encryption, the current weakest link with respect to the quantum computer threat is the secret key distribution based on public key cryptography. As its name suggests, QKD is used to distribute encryption keys whose security is based on quantum physics and is thus guaranteed for the long-term.

How does QKD work?

QKD transmits photons, which are “quantum particles” of light across an optical link. The principles of quantum physics stipulate that observation of a quantum state causes perturbation. The various QKD protocols are designed to ensure that any attempt by an eavesdropper to observe the transmitted photons will indeed perturb or disturb the transmission.This disturbance will lead to transmission errors, which can be detected by the legitimate users. This is used to verify the security of the distributed keys.

QKD implementation requires interactions between the legitimate users. These interactions need to be authenticated that are achieved through various cryptographic means. As a result, QKD can utilize an authenticated communication channel and transform it into a secure communication channel as shown in figure 2.

In theory, QKD should be combined with One-Time Pad (OTP) encryption to achieve provable security. However, an OTP requires keys, which are as long as the data to be encrypted,= and can be used only once. This would impose strong limitations on the available bandwidth as the key distribution rate of QKD is typically 1’000 to 10’000 times lower than conventional optical communications. Therefore, in practice, QKD is often combined with conventional symmetric encryption, such as AES, and used to frequently refresh short encryption keys. This is sufficient to provide quantum-safe security.

What is the need to implement quantum-safe cryptography?

The greatest threat to public cryptography is asymmetric algorithms used for digital signatures and key exchange. There are already quantum algorithms, such as the famous Shor algorithm, which can break RSA and Elliptic Curve algorithms once a universal quantum computer is available. Another famous quantum algorithm, the Grover algorithm, attacks symmetric cryptography. Fortunately, Grover’s risk can be countered by a simple expansion of the key size. For example, AES symmetric encryption scheme with 256 bit keys is considered as quantum-safe. Although certain theory estimates, a quantum computer with 4099 perfectly stable qubits could break the RSA-2048 encryption in 10 seconds (instead of 300 trillion years).

Countering the quantum computer threat will rely on following two pillars:

Post-Quantum algorithms – Development of new classical algorithms, which should resist adverse usage of quantum computer
QKD – Provide quantum-safe key exchange based on very quantum principles. Fortunately, it is available today.

Does Quantum Key Distribution offer absolute security?

For a system to be secured:
1. It must be based on sound principles
2. Its implementation must be full proof and susceptible to vulnerabilities
Contrary to classical key distribution techniques, which rely on unproven assumptions and thus do not fulfil the first criterion, the security of QKD is based on the laws of quantum physics and can be rigorously proven. Having said that, it is imperative that the practical embodiment of a QKD system also fulfils the second criterion and does not have any implementation flaws. All the announcements about QKD having been hacked were related to implementation flaws. The flaws though serious are inherent to any technological system and are rectified as technology matures. In summary, the security of QKD is based on sound principles and, if properly implemented, =guarantees absolute security for key distribution.

The post Cryptography with Quantum key distribution(QKD) appeared first on Welcome to Quantum Guru.

Quantum Cryptography- Now To Be a Reality Soon

admin — Mon, 10 May 2021 10:38:01 +0000

Why Quantum Cryptography is Important?

Users place enormous trust in banks and commercial enterprises to keep sensitive information such as credit card details, social security number etc. information safe while conducting online transactions. What if these enterprises can no longer guarantee the security of the private information, using current encryption methods? Cybercriminals are always trying to gain access to secure data, but when quantum computers come online, that information will be even more at risk of being hacked. In fact, hackers have always had head start as they have been collecting encrypted data, but needs significant computing ability to break the code. While decryption is difficult to do with conventional computing, relatively powerful quantum computer will enable breaking of the existing schemes. However, the twist comes when encryption is done using with quantum encryption, as decryption will not be straightforward.

Quantum Cryptography Definition

Quantum cryptography, also called quantum encryption, applies principles of quantum mechanics to encrypt messages in a way that no one outside of the intended recipient can decipher or read it. It takes advantage of “multiple states” and “no change theory” of quantum.

Performing these tasks requires a quantum computer, which has the immense computing power to encrypt and decrypt data. A quantum computer could quickly crack current cryptography schemes some of which are referred later in the article. Unlike mathematical encryption, quantum cryptography uses the principles of quantum mechanics to encrypt data and make it virtually “unhackable”.

Unlike mathematical encryption, quantum cryptography uses the principles of quantum mechanics to encrypt data and making it virtually unhackable.

How quantum cryptography works?

Quantum cryptography or quantum key distribution (QKD) uses a series of photons (light particles) to transmit data from one location to another over a fiber optic cable. By comparing measurements of the properties of a fraction of these photons, the two endpoints can determine the key value and whether it is safe to use. The steps are as follows:

The sender transmits photons through a filter (or polarizer), which randomly gives them one of four possible polarizations and bit designations: Vertical (One bit), Horizontal (Zero bit), 45 degree right (One bit), or 45 degree left (Zero bit)
The photons travel to a receiver, which uses two beam splitters (horizontal/vertical and diagonal) to “read” the polarization of each photon. The receiver does not know which beam splitter to use for each photon and has to guess which one to use
Once the stream of photons has been sent, the receiver inform the sender about the beam splitter used for each of the photons in the sequence they were sent. The sender then compares that information with the sequence of polarizers used to send the key. The photons that were read using the wrong beam splitter are discarded, and the resulting sequence of bits becomes the key

The photon’s state will change if it is read or copied by an eavesdropper and the endpoints will detect the change. In other words, a photon cannot be read, copied or forwarded without being detected.

Following are the list of commonly used encryption schemes

Triple DES

Triple Data Encryption Standard (DES) is a computerized cryptography where block cipher algorithms are applied three times to each data block. The key size is increased in Triple DES to ensure additional security through encryption capabilities. Each block contains 64 bits of data. Three keys are referred to as bundle keys with 56 bits per key.

RSA

RSA encryption is a public-key encryption technology developed by RSA Data Security. The RSA algorithm is based on the difficulty in factoring very large numbers. The RSA encryption algorithm uses prime factorization as the trap door for encryption. Deducing an RSA key, therefore, takes a huge amount of time and processing power. RSA is the standard encryption method for important data, including those transmitted over the Internet.

Blow Fish

Blowfish encryption is a symmetric block cipher (a method that allows encrypting data in blocks) that can be used in place of Data Encryption Standard (DES) or International Data Encryption Algorithm (IDEA). It takes a key that varies in length from 32 to 448 bits. It works for both domestic and exportable use.

Two Fish

Twofish is related to the earlier block cipher Blowfish, which is a 64-bit clock cipher that uses a key length varying between 32 and 448 bits also developed by Bruce Schneir. Twofish is also related to Advanced Encryption Standard (AES), a 128-bit block cipher that the United States government adopted as it’s specification for the encryption of electronic data by the U.S. National Institute of Standards and Technology In 2001. While Twofish was a finalist to become the industry standard for encryption, it was beaten out by AES because of Twofish’s slower speed.

AES

Advanced Encryption Standard (AES) is a cipher, meaning that it is a method or process used to change raw information (usually human readable) into something that cannot be read. This part of the process is known as encryption. The method uses a known external piece of information called “key” to uniquely change the data.

When will Quantum Cryptography become available?

The bigger question is about the availability of quantum computers and how much more time to realize quantum cryptography? There are significant engineering challenges to develop quantum computers that can take decades to solve. The technology is still in its infancy, Google has developed a machine with about 50 qubits and IBM is talking about 70 qubits.

Cracking today’s standard RSA encryption would take thousands of qubits. Adding those qubits is not easy because they are so fragile. Additionally, quantum computers today have extremely high error rates and require even more qubits for error correction. “I teach a class on quantum computing,” says University of Texas’s Brian R. La Cour. “Last semester, we had access to one of IBM’s 16-qubit machines. I was intending to do some projects with it to show some cool things you could do with a quantum computer.” That didn’t work out, he says. “The device was so noisy that if you did anything complicated enough to require 16 qubits, the result was pure garbage.”

Once that scalability problem is resolved, we will be well on our way to having usable quantum computers, he says, but it is impossible to put a timeframe on it. Brian R. La Cour guesses that we are probably decades away from the point at which quantum computers can be used to break today’s RSA encryption. There is plenty of time to upgrade to newer encryption algorithms.

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