eMudhra Blog Post Quantum Cryptography

Everything You Need to Know About Why You Can Trust PKI in the Post Quantum Cryptography World

By eMudhra Editorial on June 29, 2023
Everything You Need to Know About Why You Can Trust PKI in the Post Quantum Cryptography World


In the ever-evolving landscape of information security, the advent of quantum computing has triggered a significant paradigm shift. This shift particularly influences the Public Key Infrastructure (PKI), a set of roles, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates that provide essential security services. In this article, we delve into the essence of PKI, the looming threat from quantum computing, and why we can still trust PKI in the post-quantum era.

Understanding PKI

PKI is the backbone of digital security. It enables secure electronic transfers of information over networks through the use of digital certificates, ensuring authentication, confidentiality, data integrity, and non-repudiation. In our increasingly digital world, PKI helps maintain secure and private communication, preventing malicious entities from breaching our data privacy.

The Quantum Computing Era and Post-Quantum Cryptography

Quantum computing, still in its infancy but rapidly developing, leverages quantum bits or "qubits" to perform calculations at a speed unachievable by traditional computers. This immense computing power potentially threatens existing cryptographic systems, including PKI.

Post-Quantum Cryptography (PQC) emerges as a response to this threat. PQC comprises cryptographic algorithms thought to be secure against an attack by a quantum computer, thus preparing our defenses for the quantum era.

Quantum Threat to PKI

Traditional PKI relies heavily on algorithms like RSA and ECC, which are predicated on the difficulty of factoring large numbers or solving the elliptic-curve discrete logarithm problem, tasks deemed hard for classical computers. However, with Shor's algorithm, a large-scale quantum computer could break these encryptions, threatening the current security landscape.

Transitioning PKI to Post-Quantum

Given this threat, the PKI community has begun transitioning towards quantum-safe algorithms. Various types of PQC algorithms are currently being researched, such as lattice-based, code-based, multivariate polynomial, and hash-based cryptography. This transition involves not only adopting new algorithms but also managing the lifecycle of existing certificates for a seamless shift to the post-quantum era.

Exploring Post-Quantum Cryptographic Algorithms

As the digital world gears up for the quantum revolution, a major focus lies on developing cryptographic algorithms resilient to the enormous computational power of quantum computers. Enter Post-Quantum Cryptography (PQC) - a field dedicated to cryptographic algorithms, believed to be secure against quantum attacks. In this section, we will delve into some key types of PQC algorithms, highlighting their principles, strengths, and weaknesses. It is crucial to note that these fields are under intensive research, and the quest for the most effective, efficient, and secure algorithms is still underway. Let's demystify some of these pivotal PQC algorithms.

  1. Lattice-Based Cryptography: This type of cryptography is based on the hardness of problems in lattice theory, such as the Shortest Vector Problem (SVP) and the Closest Vector Problem (CVP). These problems are currently believed to be resistant to quantum computing attacks. Lattice-based cryptography includes cryptographic constructions for key exchanges, digital signatures, fully homomorphic encryption, and more. The primary advantage of lattice-based cryptography is that many of these constructions have security proofs, i.e., their security can be reduced to the assumed hardness of the underlying lattice problems.
  2. Code-Based Cryptography: This approach is based on error-correcting codes, particularly the hardness of decoding a general linear code (the decoding problem). The most famous of these is the McEliece cryptosystem, which remains unbroken after more than 40 years. However, the primary downside of these schemes is that the key sizes are typically quite large compared to other cryptographic systems.
  3. Multivariate Cryptography: This type of cryptography is based on the difficulty of solving systems of multivariate polynomial equations over finite fields. These systems can be designed to be computationally hard to solve (the MQ problem), forming the basis for several cryptographic primitives. One of the primary advantages of multivariate cryptography is the efficiency of the resulting cryptographic primitives. However, there have been many broken schemes in this area, and finding a secure and efficient scheme is a significant challenge.
  4. Hash-Based Cryptography: This is the oldest approach to post-quantum cryptography. Hash-based signatures, for instance, are based on cryptographic hash functions, which are believed to be quantum-resistant. One downside of many of these schemes is that they can only be used to sign a limited number of messages with a single key. However, some more recent constructions allow for a virtually unlimited number of signatures.
  5. Isogeny-Based Cryptography: This is a relatively new field of research that is based on the difficulty of certain problems in the arithmetic of elliptic curves. The most famous example of this is probably the Super-singular Isogeny Diffie-Hellman (SIDH) scheme. While this area shows promise, it is still new, and the security of these schemes is less well-understood compared to the others.

Reliability of Post-Quantum PKI

Despite the considerable changes anticipated, experts posit that we can trust PKI in the post-quantum world. Standardization efforts, led by entities like the National Institute of Standards and Technology (NIST), aim to vet and approve robust, quantum-resistant algorithms. These efforts are expected to fortify PKI against quantum threats, reinforcing its reliability.

Implementing Post-Quantum PKI

As organizations prepare for post-quantum PKI, several best practices should guide the transition. These include conscientious vendor selection, rigorous key management, and meticulous certificate lifecycle management. By preparing in advance and following these practices, organizations can ensure a smooth transition to quantum-resistant cryptographic infrastructure.

Shor's Algorithm: Business Implications in the Post-Quantum World

Invented by Peter Shor in 1994, Shor's algorithm is a quantum algorithm capable of factoring large numbers and computing discrete logarithms in significantly reduced time compared to classical algorithms. Given a sufficiently powerful quantum computer, it could break many of the public-key cryptosystems currently in use, such as RSA and ECC, causing substantial disruption to business practices that rely on these cryptosystems for secure communications and transactions.

Here are some ways Shor's algorithm could impact business in the post-quantum world:

  • Data Security: Businesses rely on secure data encryption to protect sensitive information. With Shor's algorithm, quantum computers could potentially decrypt data encrypted with traditional methods, posing a risk to data privacy and security. Companies may need to reassess their data protection strategies and consider implementing quantum-resistant encryption methods.
  • Financial Transactions: Online banking, e-commerce, and digital payments all depend on secure cryptographic systems. The potential for Shor's algorithm to break these systems could have serious implications for financial security and trust in online transactions.
  • Business Continuity: If quantum computers become widely available and can run Shor's algorithm effectively, businesses may face significant disruption as they transition to post-quantum cryptographic systems. Planning for this transition will be a critical aspect of business continuity management.
  • Investment in Quantum-Resistant Technologies: Businesses, especially in the technology and finance sectors, may need to invest in the development or adoption of quantum-resistant technologies to protect their operations in the post-quantum world. Early adoption could provide a competitive advantage.
  • Regulatory Compliance: Laws and regulations concerning data protection are likely to evolve in response to advances in quantum computing. Businesses will need to ensure they remain compliant with these changing regulations, which may require substantial time and resources.

While the development of quantum computers capable of running Shor's algorithm is still underway, the potential impact on businesses worldwide is significant. Consequently, understanding and preparing for the potential risks associated with the post-quantum era is becoming increasingly crucial for businesses across sectors.

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