# The Future of Cybersecurity is Quantum

Cryptography today mainly relies on math that is easy to do in one-way, and extremely difficult to do in the opposite way. Turns out, some of that math has to do with factoring very large prime numbers. For instance, it is easier to multiply 73 by 79 to get 5767 than to factor 5767 to get 73 and 79. In reality, way larger prime numbers than 73 and 79 are multiplied to result it in even larger prime numbers that are magnitudes harder for computers to factor.

In fact, it could take computers today billions of years to factor very large prime numbers, and hence, our information online is protected. However, it would hypothetically take quantum computers a “matter of seconds” to do so. [1] As a result, post-quantum cryptography has emerged as a research field to create cryptographic techniques that quantum computers could not crack easily. Cleary then, in the future, quantum mechanics will lie on the code-breaking side.

On the other side, the code-making side, and also an emerging area of research, quantum cryptography takes advantage of quantum principles to ensure the privacy of information. The most referred to technique in quantum cryptography today is quantum key distribution (QKD). Quantum key distribution guarantees, through the laws of physics, two parties to have a key known only to them. It is used only to produce a key, which can be used with traditional encryption algorithms to encrypt and decrypt messages, and not to send information securely. [2]

Quantum key distribution relies on a one-time pad, a technique in which a private key is generated randomly and used only once to first encrypt a message by a sender, and then to decrypt the message by a receiver with an identical one-time key. [3] Assuming both parties have access to the same key, the one-time pad technique makes codes impossible to crack because every key generated is random and has no relation to previously generated keys. The one-time pad is a traditional cryptographic technique that ensures the impossibility of cracking codes, but assumes that the keys are delivered securely –there are no eavesdroppers that copied the key. That’s where quantum cryptography comes into play.

Photons, or any other particles that fall under the laws of quantum mechanics, are used to transmit the key from the sender to the receiver. Because, according to quantum mechanics, it is “always possible” to know that a quantum particle has been observed, if the key-carrying photon has been observed, the key is dropped. [4] Once a key that has not been observed reaches the receiver, the party would have a one-time pad. After the key has been delivered, the parties can communicate over any channel securely.

Quantum encryption has come a long way from theory. The very first “quantum transaction” was conducted by researches in Vienna who deposited three thousand euros into their bank account in 2004. [2] Soon after, notably ID Quantique, who secured the results of a 2007 election in Geneva, helped commercialize quantum encryption technologies. The quantum cryptography industry is mainly targeting governments and businesses that are in need of high-security, but the technology is unlikely to be widespread anytime soon as current security measures are sufficient to tackle today’s attackers. Nonetheless, the technology can be made available, especially with the existing fiber optic networks in many countries.

[1] Adrian Bridgwater, “Five ways quantum computing will change cybersecurity forever” on *Racontuer.*

https://www.raconteur.net/technology/five-ways-quantum-computing-will-change-cybersecurity-forever

[2] Devin Powell, “What is Quantum Cryptography?” on *Popular Science.*

https://www.popsci.com/what-is-quantum-cryptography

[3] One-Time Pad. https://en.wikipedia.org/wiki/One-time_pad

[4] Emerging Technology, “Chinese satellite uses quantum cryptography for secure video conference between continents,” on *MIT Technology Review.*

https://www.technologyreview.com/s/610106/chinese-satellite-uses-quantum-cryptography-for-secure-video-conference-between-continents/

### One comment on “The Future of Cybersecurity is Quantum”

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Interesting post on quantum physics and cryptography. The explanation on quantum key distribution was clear and made a relevant connection to cryptography.