What Are The Differences between Classical, Quantum and Post-Quantum Cryptography?

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In early 2020, there were 4.7 billion Internet users worldwide, a staggering 1,187% growth over just two decades. Furthermore, our increasing reliance on Internet-powered technologies generates massive amounts of data ( – that’s 1 followed by 21 zeros!)

Much of this data contains “sensitive” information that needs to be encrypted. We use specialized encryption systems to ensure that this data can only be accessed by authorized users in possession of encryption keys.

For decades, we’ve been using the same cryptographic systems, like RSA, to protect our data. These cryptographic systems were largely effective – but very soon, they’ll become powerless against the quantum threat. And the only way to prevent a global collapse of our IT infrastructure is to use cryptography that is resistant to quantum attacks.

But what differentiates classical cryptography from the newer quantum cryptography? How is quantum cryptography different from post-quantum cryptography? And how exactly can novel quantum-safe cryptosystems protect us?

Let’s explore the answers to these questions below!

Classical, Quantum, and Post-Quantum Cryptography: The Differences

The purpose of all three types of cryptography is to encrypt data and ensure its security, integrity, and authenticity. However, the three cryptography technologies drastically differ in how they protect data.

Here’s a quick summary of the differences between classical cryptography, post-quantum cryptography, and quantum cryptography:

  • Classical cryptography uses difficult mathematical problems to protect data from non-quantum threats.
  • Post-quantum cryptography also relies on mathematical problems, but they’re much more difficult than in classical cryptography and can withstand quantum attacks.
  • Quantum cryptography exploits the properties of quantum mechanics, rather than difficult math problems, to protect data from quantum threats.

The differences don’t end here though. Let’s take a slightly deeper look into each cryptographic system to get a better idea of their differences.

Classical Cryptography

Classical cryptography encompasses the standard encryption algorithms that pretty much every business or government entity uses today to protect its data. Think systems like AES (Advanced Encryption Standard) or RSA (Rivest-Shamir-Adleman).

Classical cryptography is based on intractable mathematical “puzzles” that would take a classical computer thousands of years to solve. These “puzzles” can be built on math problems like large number factorization and discrete logarithms. Classical computers, no matter how powerful, cannot crack these problems and decrypt protected data in any reasonable time span. So unless hackers somehow get their hands on your encryption keys, your data should be safe.

In classical cryptography, the communicating parties share a secret sequence of random numbers called a “key.” In symmetric encryption, the communicating parties use the same key both to encrypt and decrypt data. In asymmetric (public-key) encryption, the sender uses the recipient’s public key (visible to anyone) to encrypt data, while the recipient uses their secret private key to decrypt data.

The security of classical cryptography depends on the secrecy of the key. If you keep your keys away from prying eyes, it’s practically impossible for your data to be compromised – at least, until powerful quantum computers arrive.

This neatly transitions us into the next cryptographic technology – post-quantum cryptography.

Post-quantum Cryptography

Post-quantum cryptography, or PQC, is an evolution of classical cryptography. Like classical cryptography, PQC is based on math problems. However, PQC extends classical cryptography’s property of intractability to quantum computers. To achieve this, PQC employs much more difficult math problems that are believed to be unsolvable even for quantum machines.

The fact that both classical and post-quantum systems rely on math problems leads to an interesting benefit – PQC solutions can be easily implemented in code and delivered to any device via software updates.

Post-quantum cryptography systems are mainly asymmetric (public-key), though there are symmetric systems in development as well. The reason why PQC systems tend to be asymmetric is that symmetric cryptography is believed to be resistant to quantum computers – at least, for the foreseeable future.

In asymmetric cryptography, the private key is mathematically related to the public key. This means that with enough computing power, hackers could derive the private key from the public key (which is visible to anyone). This is unachievable on classical computers but will become very easy with quantum machines.

Hackers could potentially use your public key as an entry point into your corporate network. Symmetric algorithms don’t have this weakness because they imply that the encryption/decryption key never goes public. And that’s why for now, most PQC algorithms are public-key or asymmetric.

Quantum Cryptography

Just like post-quantum cryptography, quantum cryptography’s aim is the protection of data from quantum threats. But the way it works is very different.

Quantum cryptography (sometimes called quantum encryption) is based on physics and relies on the properties of quantum mechanics for data security. Quantum cryptography harnesses the unpredictable nature of matter at the quantum level to encrypt and decrypt messages and guarantee the security of your communications.

Information in classical and post-quantum cryptography is encoded in bits, while quantum cryptography uses qubits. In this sense, quantum cryptography is just like quantum computers.

The best-known example of quantum computing cryptography today is quantum key distribution, or QKD. QKD makes it possible for two parties to share data in secure, unbreakable, eavesdropper-safe ways.

Unlike the other two methods, QKD can help the communicating parties detect eavesdropping attempts. Because of the properties of quantum mechanics – like the no-cloning theorem – hackers cannot directly measure data transmitted over a QKD connection. And if they tried, they would introduce errors to the qubits, immediately alerting the communicating parties that their connection isn’t secure.

Aside from that, quantum cryptography is theoretically resistant to increases in quantum computing power. No matter how strong the onslaught of quantum computers is on quantum cryptography, it’s believed that it won’t break. Computing power cannot bend the laws of physics, so quantum cryptography is protected by the laws of nature itself.

That being said, remember the stress on “theoretical” when considering the benefits of QKD. If implemented badly, QKD is much less secure than PQC. Setting up a QKD communication channel requires careful configuration and a proper set of hardware.

And speaking of hardware, QKD requires dedicated optical fiber connections and photon emitters to send and receive encrypted data. At enterprise scales, setting up an infrastructure for QKD can be a multi-million-dollar endeavor. You can’t just inject standard QKD into your infrastructure via software updates – specialized hardware channels are a prerequisite for QKD.

However, some quantum cybersecurity vendors are working on digital alternatives to QKD. These alternatives retain the beneficial properties of standard QKD while being much easier to deploy.

Post-Quantum Cryptography: Quantropi Leads The Way With QiSpace™

In the not-too-distant future, quantum computing algorithms will break many of the encryption protocols that today’s networks and information security depend on. This will endanger data and make organizations, governments, and individuals vulnerable to data theft and misuse. To prepare for this new era of quantum computing, many governments are primarily supporting the development of post-quantum cryptography because of its cost-effectiveness compared to quantum cryptography.

But while PQC is promising, most PQC algorithms have some serious disadvantages. We believe that to stay ahead of the fast-approaching quantum threat and to protect their communication networks, customers and users, organizations and governments need to deploy next-generation PQC solutions.

Quantropi’s asymmetric cryptographic solution, MASQ™, offers a proprietary, novel PQC algorithm that is much more efficient than NIST finalists. MASQ™ doesn’t require you to upgrade your infrastructure just to run PQC, and it also can operate on resource-constrained devices like smartphones or laptops.

MASQ™ is part of Quantropi’s flagship quantum-safe platform QiSpace™. To learn more, contact an authorized Quantropi representative today.

Much of this data contains ‘sensitive’ information that needs to be encrypted. Many encryption methods are used to ensure that this data can only be accessed by authorized users in possession of ‘encryption keys’.

But are these ‘traditional’ or ‘classical’ methods truly effective at keeping data encrypted and safe?

What differentiates Classical Cryptography (CC) from newer Quantum Cryptography (QC)?

And finally, do we need Post-Quantum Cryptography (PQC)? Why?

Classical and Quantum Cryptography: The Differences

In general, the purpose of both Classical Cryptography and Quantum Cryptography (also known as quantum security or quantum encryption) is to encrypt data, and ensure its security, integrity and authenticity. But there are several differences between the two approaches.

First, CC is based on intractable mathematical puzzles that are unsolvable on a classical computer for billions of years. These puzzles include large number factorization and discrete logarithms. It is their intractable nature that  prevents unauthorized users from eavesdropping on encrypted messages in a CC-protected system. QC however, is based on Physics and relies on the properties of Quantum Mechanics for data security. Interestingly, PQC (covered in the next section), takes a similar approach as CC by extending the latter’s property of intractability to quantum computers. In other words, it builds on Math puzzles believed to be intractable even by quantum computers to provide secure communications.

In CC, the communicating parties share a secret sequence of random numbers or a ‘key’. So the security of the method depends on the secrecy of the key, leaving it vulnerable to security loopholes. QC harnesses the unpredictable nature of matter at the quantum level (‘qubits’) to encrypt and decrypt messages, and guarantee more secure communication.

Two commonly-used  methods for Advanced CC are Data Encryption Standard (AES) and Public Key Cryptography (PKC). In the former, the key consists of a randomly-chosen, long string of bits which determines the security of the communication channel. With the latter approach, each user has two keys: public and private, each of which does only half of the encryption/decryption process. The numbers created by the combination of the key and the encoding can reach staggering proportions, adding to the system’s complexity and cost. Moreover, with exponential increases in computing power and the encroaching approach of quantum computing, these numerical keys are no longer able to provide truly secure communication. Unlike CC methods, QC provides ways for users to securely establish secret keys and detect eavesdropping if it occurs. Therefore, it can protect data in ways that current encryption methods – some of which have been around for over two decades – can’t.

The best-known example of QC today, Quantum Key Distribution (QKD) makes it possible for parties to share data in secure, unbreakable, eavesdropper-safe ways.

Post-Quantum Cryptography: Quantropi Leads The Way With QEEP™

In the not-too-distant future, QC algorithms will likely break many of the encryption protocols that today’s networks and information security depends on. This will endanger data and make organisations, governments and individuals vulnerable to data theft and misuse. To prepare for this new era of quantum computing, many governments are promoting the development of Post-Quantum Cryptography (PQC).

But the UK’s National Cyber Security Centre (NCSC) has expressed scepticism  about the promised benefits of these technologies, including maths-based PQC algorithms, physics-based Quantum Random Number Generation (QRNG) and even QKD. At Quantropi, we think this scepticism is warranted. We believe that to stay ahead of the fast-approaching QC curve, and to protect their communication networks, customers and users, organisations and governments need to deploy next-generation PQC solutions.

Quantropi’s unique Quantum Entropy Expansion and Propagation (QEEP™) is a secure application of the logical implementation of n-qubit quantum permutation gates. QEEP™ offers quantum-secure random key exchange, making information uninterpretable over unlimited distances. Plus, it works with existing infrastructure and offers scalable security to accommodate growing network bandwidth demands.

Protect your organisation and ensure quantum-safe communication with QEEP™. To know more, contact an authorized Quantropi representative today.

Quantum-secure any application, product, network, or device with the QiSpace™ platform — without having to sacrifice performance or make major investments in new technology or infrastructure. See for yourself how only QiSpace™ offers TrUE quantum security via all three essential cryptographic functions. Leverage asymmetric encryption algorithms (the “Trust” or “Tr” of “TrUE”) via MASQ™, symmetric encryption (“U” for “Uncertainty”) via QEEP™ and strong random numbers (“E” for “Entropy”) via SEQUR™.  Make it TrUE with QiSpace™ — and protect your business, brand, and customer promise. Now and forever. 

To learn more about our quantum-secure solutions, don’t hesitate to get in touch with our experts!

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Timothy Stapko

Timothy Stapko is a senior software engineer at Microsoft with 20+ years of experience in the information technology industry specializing in embedded systems, IoT security, security (SSL/TLS), and 9+ years of experience leading projects and a team of engineers on two commercially successful implementations of TLS for resource-constrained embedded systems (including cryptography, X.509, DTLS, HTTPS, etc.). Tim also has experience with US federal information standards (e.g., FIPS) and other standards and certifications (e.g., Common Criteria/EAL) and specializes in C, C++, FIPS 140-2, Linux, SSL, TLS, TCP/IP

Bond Vo

Bond Vo is the Business Analyst of Quantropi. Along with Quantropi, Bond has been dynamic in accordance with a fast and evolving startup environment and is responsible in a wide range of areas including market research, funding, and more involved in the controller roles to oversee day to day accounting operation as well as build financing models and budget to achieve company’s ultimate goals/objectives. Bond has applied best practices consistently and successfully supports equity, debt, and non-dilutive funding for Quantropi since joint the team. He earned a Bachelor of Commerce concentrated in Finance from Carleton University. Outside of his professional career, Bond also participated in volunteer for the Vietnamese Immigration Student Association (VISA) to help and support students as well as newcomers in Canada.

Dr. Randy Kuang

Randy holds a doctorate in quantum physics. His research findings have been published in top international journals and named “Kuang’s semi-classical formalism” by NASA in 2012. With a career spanning IT, including with Nortel as senior network researcher & developer, he co-founded inBay Technologies in 2009, serving as CTO of the cybersecurity platform. As the first recipient of a patent for two-level authentication (2011), Randy is a prolific inventor, with 30+ U.S. patents in broad technology fields, such as WiMAX, optical networks, multi-factor identity authentication, transaction authorization, as well as concepts, technologies and industrial applications for quantum key distribution.

Cory Michalyshyn

Cory brings a breadth of experience to the Quantropi team, working fractionally with multiple SaaS technology companies as CFO, and as the CFO with Celtic House Venture Partners. Prior to these roles, Cory was CFO and COO at Solink, and played a lead role in the metrics-led pivot to a direct-sales SaaS model, followed by multiple VC-backed funding rounds and their recognition as one of the fastest growing start-ups in Canada. He qualified as a CPA while serving technology, VC & PE-fund clients at Deloitte, and earned his Bachelor of Commerce at Queen’s University.

Ken Dobell

Ken leads marketing strategy at Quantropi. In high demand as a consultant with 25 years’ experience in performance media and an award- winning creative background, he has completed successful transformations, (re)branding and product development mandates with KPMG, Keurig, Fidelity, Eddyfi, Coveo, and more, and provides digital advice to the CMA. Previously, Ken pivoted an offline advertising brokerage to a leading-edge, data-driven performance agency as President of DAC Digital, held a progression of international leadership roles with Monster.com, pioneered a range of multi-channel initiatives as VP Marketing with a global franchisor, and introduced a mobile-first programmatic media offering to Canada within WPP.

Raj Narula, P.Eng.

A seasoned technology executive, business builder and angel investor, Raj has held operational and advisory roles in Recognia (Trading Central), Belair Networks (Ericsson), March Networks (Infinova), Sandvine (Procera), Neurolanguage (ADEC), Bridgewater Systems (Amdocs), Vayyoo (Cafex), TenXc (CCI), 1Mobility (Qualys) and others. Having divided his time among North America, EMEA and Asia-Pac for over 20 years, Raj speaks several languages. He grew up in Asia, Europe, South America and Canada, and holds a B.Eng degree in Mechanical Engineering from the University of Ottawa. He is also a co-founder and Charter Member of the Ottawa chapter of TiE (the Indus Entrepreneur).

Michael Redding

Before joining Quantropi, Mike was Managing Director and co-founder of Accenture Ventures, where he grew a global portfolio of strategic partnerships and 38 equity investments in emerging technology startups.

During his nearly 30 years with Accenture, he incubated and launched technology innovations for enterprises across multiple geographies and industries. Ever-passionate about bold ideas with game-changing results, he speaks frequently on the impact of emerging technology on large organizations.

With a bachelor’s degree in Electrical Engineering and Computer Science from Princeton, and a Master’s in Biomedical Engineering from Northwestern, Mike is a former member of the Board of Directors for the Accenture Foundation and Board Observer for startups Maana and Splice Machine.

Alex He

Alex is a product-oriented project manager who bridges the gaps between the company’s engineering and commercial teams. He has over ten years of experience in the analysis, design and development of enterprise-class applications, with a particular focus on creating optimal user experiences (UX). Ever passionate about cybersecurity solutions that can deliver solid security without unreasonably sacrificing customer convenience, Alex is the lead inventor of a registered patent on user interface security. He is committed to helping ensure that the Agile software engineering team at Quantropi delivers consistently high-quality, high crypto-agility cybersecurity solutions for next-generation communications.

Nick Kuang

As VP Corporate Services, Nick plans, directs and coordinates a wide range of activities aimed at achieving Quantropi’s vision of the Quantum Internet. He has a keen interest in transformative technologies and the possibilities they offer for bettering our everyday lives. A pharmacist by training, Nick nurtures teams with a focus on integrity and collaborative effort, coupled with strong attention to detail. With prior experience in a successful biotech start-up developing point-of-care test kits, he enjoys the fast pace and challenge of the start-up environment.

Tina Wang

Tina develops websites and participates in a range of different projects, using new frameworks for front-end UI, along with Vuejs, Angula, Beego, Ruby on Rails, and Electron. She developed Quantropi’s desktop CipherSpace application by integrating Electron, Webassembly and Go, to ensure a good user experience, as well as perfect operating system compatibility. She is also part of the dynamic and efficient QKD-NODE project team. Tina is always looking for new ways to increase her knowledge, improve her technological proficiency and enhance her strong execution and implementation skills. Prior to Quantropi, Tina served as a full-stack web developer at Sunny Future, where she maintained a WordPress home site and managed the release of new content for the company.

Pauline Arnold

As James Nguyen’s EA, Pauline Arnold brings more than 40 years of experience in complementary customer service and administrative roles. Prior to Quantropi, she served 20 years as Branch Manager and an assistant in investments, and over 20 years at Metropolitan Life Canada in various aspects of the insurance sector – assisting clients, management and colleagues to complete tasks, solve problems, address questions and achieve goals. She also worked part-time for Royal Lepage Performance for 5+ years as a receptionist & admin, and for 5 years was chair of the TKFG’s charity golf tournament.

Renato Pontello

Renato has 30 + years of experience as a trusted legal advisor and strategist. As an executive he has assisted numerous companies and their Boards of Directors to plot out and implement significant growth, diversification and reorganization plans in challenging circumstances. He was lead counsel on the sale of Zarlink Semiconductor’s $680 million dollar business as part of a takeover bid. At Zarlink he negotiated significant development, manufacturing, supply, distribution and IP licensing agreements with leading suppliers (eg Cisco, Nokia, Ericsson, Medtronic, Starkey, TSMC, Global Foundries, etc.). Renato has been involved in M&A, restructuring, financings and commercial contracts for dozens of companies. He also provides legal support in regards to intellectual property, securities, real estate leasing and employment law. He represents clients mostly in the SaaS, wireless, proptech, quantum, renewables, e-commerce, engineering and real estate conversion space.

Dafu Lou

Dafu is Quantropi’s Director of engineering. Prior to Quantropi, he served as a technical leader at Irdeto, a world-leading provider of digital platform security software, where he was responsible for white-box cryptography, cloaked CA secure core, and iOS/android application protection services, among others. Prior to Irdeto, Dafu served as a senior software engineer at SecureNex Systems, where he led the implementation of an SSL-VPN solution and ECC-based secure data storage & PKI. He earned his Ph.D. in electrical engineering from the University of Ottawa in 2009. Dafu is also a part-time professor, teaching VLSI, Cryptography and other subjects at uOttawa.

Christopher McKenzie

With his extensive experience in software development and strong analytical skills, Chris can handle the entire end-to-end software development life cycle. Prior to Quantropi, he served as Director of Product Development at Sphyrna Security, Inc., where he managed the delivery of security compliance automation and data diode appliance products, and as Commercial Software Development Manager at Cord3, Inc., where he managed the development of an advanced data access policy management product. Chris graduated from Computer Science at Algonquin College and the Ottawa School of Arts in 1998. Read less

Eric Chan

Eric Chan a.k.a. EEPMON is a Crypto / Digital Artist with 15 years in the industry – and Quantropi’s Creative Emissary. His hybrid fractal/digital creations have been seen in fashion, comics to museums and has exhibited worldwide. EEPMON’s collaborations include Canada Goose, MARVEL, Snoopy, Microsoft Xbox, Canada Science & Technology Museum and was a TEDx performing artist. In 2018 he represented Canada on its first Creative Industries Trade Mission led by Canada’s Minister of Heritage and serves on the Canadian Museums Association‘s Board of Directors. At the same time, he is currently completing his Master of Information Technology – Digital Media at Carleton University. 

Patricio Mariaca

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Marco Pagani

Marco Pagani began his long and successful career as a senior executive in Ottawa’s high-tech sector in 1985, with Nortel Networks (then Bell-Northern Research). He rose across two decades to become president of several Nortel Business Units, managing more than 2,000 employees and over $1 billion in revenue. Having gone on to advise numerous organizations, as well as guide a range of companies through complex, critically necessary turnarounds, he is particularly respected for placing a strong emphasis on ethics and corporate governance in building the culture of the corporate and not-for-profit organizations he leads and supports.

Lawrence O’Brien

Lawrence O’Brien is a founder of Calian Group and former Mayor of Ottawa. Larry founded Calian Technology Ltd. in 1982 with a $35 investment and built it into a $200M/ year profitable, dividend-paying public company by 2006. As the CEO of Calian, Larry executed an IPO in 1993, completed five significant acquisitions, and managed the overall strategic growth of Calian from 1982 until 2006. After retirement from Calian in 2006, Larry served as the 58th mayor of Ottawa and proceeded to push forward four major economic development projects, including a Light Rail Transit tunnel in the core of the city, a new Convention Centre, now known as the Shaw Centre and a new trade show facility and a major urban renewal project that rebuilt 40 acres of dilapidated downtown Ottawa called Lansdowne Park into a vibrant, destination for citizens and tourist.

Dat Nguyen

Dat Nguyen has executive experience with top global consultancies such as IBM, Accenture, Ernst & Young (EY), and decacorn start-up Grab at C-Level roles.

During 20 years of consulting, Dat has worked with multiple companies across Canada, the USA, the Caribbean, and the Asia Pacific with CEO roles and leadership such as CEO for Accenture Vietnam, CEO of Grab Vietnam, and Partner of EY Consulting leading the technology practice (including Cybersecurity) in Indochina (Vietnam, Laos, Cambodia).

Dat is a tech entrepreneur, a co-founder, and a digital ecosystem builder. He is passionate about new and innovative technologies and is involved in multiple companies across verticals such as AI, Blockchain, Web3, Cybersecurity, InsurTech, and FinTech. Dat is currently a member of the ASIA CEO Club.

Dat earned the Executive Education at Harvard University, John F. Kennedy School, and received the Executive Certificate in Public Leadership in 2018.

Tanya Woods

Tanya Woods brings more than a decade of successful strategic advocacy experience to her role at the Chamber of Digital Commerce Canada. Tanya most recently served as the Interim Executive Director for the Blockchain Association of Canada and is a champion for Canada’s digital innovation ecosystem, domestically and globally. Tanya has held senior-level positions in the industry, representing national and multinational organizations in the telecommunications, technology, and entertainment sectors, including BCE Inc., Microsoft, Hut 8 Mining, and Nintendo. She has also advised and represented the Government of Canada in global trade negotiations and on the growth of the country’s blockchain ecosystem. Tanya is a global public speaker and published author with degrees from the London School of Economics, Ottawa University, and American University Washington College of Law. She was named among the top 10 “Leading TechWomen in Canada” by the Government of Canada, a “Trailblazer” by the Canadian Broadcasting Corporation, and a “Top 40 under 40” in Canada’s Capital by the Ottawa Chamber of Commerce and the Ottawa Business Journal.

James Nguyen

Prior to leading Quantropi, James was Chief Investment Officer & VP Asia Operations for a group of private and public real estate, mining, energy storage, graphene technologies and manufacturing interests, where, in his responsibilities for strategy, banking and global expansions, he secured large-scale investments and partnerships for commercializing graphene applications across multiple industries. A graduate of Carleton in Economics, he previously achieved success managing a mid-market portfolio (professional services, public sector, Asian markets) at RBC for over a decade. James has been on the HKCBA board, held advisory positions with technology start-ups and gives back as volunteer, fundraiser and mentor.