Post-quantum cryptography explained, risks of quantum attacks, and steps to secure data, systems, and infrastructure for a quantum-resilient future.
Today’s digital systems are fundamentally built on cryptography, which is the field of mathematics dedicated to protecting information. Cryptography safeguards data by verifying identities, maintaining data accuracy, and preventing unauthorised access. Whether it’s a secure web connection, an online payment, or a business communication, cryptographic protocols are essential for keeping sensitive information secure.
Cryptography operates by transforming clear, understandable data (plaintext) into an encrypted
form (ciphertext) using specialized algorithms and keys. Only individuals or systems with the
correct cryptographic key can decrypt the data and access its original content. In the field of
cybersecurity, cryptography is essential for providing four core security properties.
- Non-repudiation: preventing denial of performed actions.
- Confidentiality: preventing unauthorized access to information.
- Integrity: ensuring data cannot be modified without detection.
- Authentication: verifying the identities of users and systems.
In real-world applications, cryptography serves as the foundational trust mechanism for the Internet. It enables secure digital operations. Without it, digital services such as banking, cloud computing, healthcare systems, and industrial automation would be vulnerable to interception and manipulation.
Cryptography in Daily Digital Life
Although often unnoticed, cryptography protects numerous everyday digital activities; demonstrate that cryptography is foundational to global digital trust. For example, HTTPS uses encryption to keep website data safe between your browser and the server. Online payments depend on cryptography to check transactions and prevent fraud. Companies also use VPNs to protect business data when employees connect remotely.
Types of Encryption
Cryptographic systems rely primarily on two types of encryption models: symmetric and
asymmetric encryption.
Symmetric Encryption
Symmetric encryption uses a single shared key for both encryption and decryption. Since only one key is involved, the process is computationally efficient and well-suited for encrypting large volumes of data.
Common symmetric encryption algorithms, which use the same key for encryption and decryption, include AES, DES, 3DES, Blowfish, Twofish, ChaCha20, and RC4. These algorithms are widely used for securing data at rest, VPN traffic, and banking transactions due to their speed and efficiency.
AES (Advanced Encryption Standard): The industry standard AES-256 is widely used in enterprise security systems, disk encryption solutions, and TLS communication. Even in the presence of quantum computing, symmetric encryption remains resilient because the main quantum attack (Grover’s algorithm) only reduces effective key strength rather than completely breaking the algorithm.
Increasing key size can compensate for this effect. For example, once a secure HTTPS session is established between a browser and a server, AES encryption protects all subsequent data exchanged during the session.
Asymmetric Encryption
Asymmetric encryption, or public key cryptography, uses two mathematically related keys:
- Public key – distributed openly.
- Private key – kept secret.
Asymmetric encryption keys (public and private) are derived together using mathematical algorithms that create a linked pair. These algorithms rely on trapdoor functions. Mathematical operations easy to perform in one direction but almost impossible to reverse without a specific key, such as factoring large prime numbers (RSA) or discrete logarithms (Elliptic Curve Cryptography). Data encrypted with the public key can only be decrypted using the corresponding private key.
Common asymmetric (public key) encryption algorithms include RSA, ECC, and DSA, which use key pairs (public/private) for secure communication.
- RSA (Rivest-Shamir-Adleman): The most commonly used algorithm for encryption and digital signatures.
- ECC (Elliptic Curve Cryptography): Offers high security with smaller key sizes, making it more efficient than RSA.
- DSA (Digital Signature Algorithm): Primarily used for generating digital signatures.
- Diffie-Hellman (DH): A widely used key exchange algorithm.
These algorithms enable secure identity verification, digital signatures, and secure key exchange for secure data sharing without exchanging secret keys. Such as when a user connects to a secure website, the server presents a digital certificate containing its public key. The client verifies the certificate through trusted Certificate Authorities (CAs) before establishing a secure, encrypted session. However, asymmetric cryptography is also the primary area vulnerable to future quantum computing attacks.
The Hybrid Approach
Symmetric encryption is commonly paired with asymmetric encryption in a hybrid model to balance security and performance. They Are Combined (Hybrid Encryption) because:
- Asymmetric (Slow/Secure): Used to securely share a secret key over an open network (like the internet) without a prior relationship.
- Symmetric (Fast/Efficient): Used for the rest of the session because it can encrypt large amounts of data without overwhelming the resources.
The Quantum Computing Revolution
Quantum computing represents a fundamentally different computational paradigm compared with traditional computing.
Classical Computing
Traditional computers operate using binary bits, which represent either 0 (Low) or 1 (High). All computing operations are based on manipulating these binary states.
Quantum Computing
Quantum computers use qubits, which exploit principles of quantum mechanics:
- Superposition: a qubit can represent multiple states simultaneously.
- Entanglement: qubits can influence each other even across distances. These properties allow quantum computers to explore several computational possibilities simultaneously, enabling them to solve certain mathematical problems dramatically faster than classical systems.
Quantum Computing vs Supercomputing and Grid Computing
Quantum computing should not be confused with existing high-performance computing technologies, such as supercomputing and grid computing.
Supercomputing
Supercomputers aggregate thousands of classical processors to perform large-scale scientific simulations and computations. They are widely used in weather forecasting, molecular modelling, and financial modelling.
Grid Computing
Grid computing distributes workloads across many connected systems to perform large computations collaboratively.
Quantum Computing
Quantum computing is fundamentally different. Instead of increasing computational speed through parallel processing, it introduces entirely new algorithms capable of solving specific mathematical problems exponentially faster than classical computers.
Large financial institutions and stock exchanges already use supercomputers and grid computing for high-frequency trading and risk modelling. However, these systems do not pose any threat to modern cryptography, because they still rely on classical computing principles. Quantum computing, in contrast, introduces capabilities that may eventually break widely used cryptographic algorithms.
The Quantum Race: Progress and Predictions
Quantum computing is progressing rapidly due to significant investments from governments and technology companies.
IBM has published a roadmap targeting fault-tolerant quantum processors before the end of this decade, with large-scale systems expected to follow shortly thereafter. (Live Science) Google researchers have also demonstrated significant algorithmic improvements, suggesting that quantum systems with fewer than one million qubits could potentially break RSA-2048 encryption in under a week. (The Quantum Insider).
Many cybersecurity analysts estimate that “Q-Day,” the moment when quantum computers can break widely used public-key cryptography, may occur in the early 2030s, though progress in hardware and algorithms could accelerate this timeline. (Palo Alto Networks) Even more aggressive predictions from industry leaders suggest that early cryptographically relevant quantum systems could emerge sooner as quantum hardware matures. (The Economic Times).
These developments indicate that the transition to post-quantum cryptography (PQC) should begin well before such systems become operational.
Quantum Threats to Modern Encryption
The primary threat from quantum computing arises from Shor’s algorithm, which can efficiently solve mathematical problems underlying widely used encryption systems. Algorithms vulnerable to quantum attacks include, but are not limited to, RSA, Diffie-Hellman, Elliptic Curve Cryptography (ECC), etc.
Because current public-key infrastructure (like RSA and ECC) relies on the computational difficulty of these specific problems, quantum computers will be able to derive private keys from publicly available keys. Consequently, algorithms with shorter key lengths are significantly riskier and less secure against future quantum attacks, creating an urgent need for post-quantum cryptography (PQC).
A sufficiently powerful quantum computer could theoretically break RSA-2048 encryption in hours, whereas classical computers would require billions of years to perform the same task. (IBM Research). This vulnerability introduces the concept of “Harvest Now, Decrypt Later,” where attackers collect encrypted data today and decrypt it once quantum capabilities become available.
Immediate Security Actions for Organizations
Organizations can begin preparing for quantum threats today without waiting for quantum computers to become commercially available.
1. Cryptographic Asset Discovery
Security teams should identify all systems that rely on cryptography, including:
- VPN services
- Encrypted storage
- PKI infrastructure
- Authentication systems
- TLS and HTTPS communication.
Understanding cryptographic dependencies is essential for future migration planning.
2. Eliminate Weak Cryptographic Algorithms
Legacy algorithms should be replaced with modern standards, such as:
- AES-256
- SHA-256 or SHA-3
- Strong elliptic curve algorithms
Weak algorithms such as MD5, SHA-1, and short RSA keys should be retired.
3. Improve Key and Certificate Management
Reducing certificate lifetimes and implementing automated certificate management reduces risk exposure. Best practices include:
- Automated certificate rotation
- Strong key storage using HSMs
- Secure PKI governance
- Regular certificate audits
4. Modernize Hardware Infrastructure
Legacy hardware may not support future cryptographic algorithms. Organizations should evaluate:
- VPN gateways
- Firewalls and load balancers
- Hardware security modules
- Cryptographic accelerators
Replacing outdated infrastructure ensures compatibility with emerging PQC standards.
5. Training the Cybersecurity Workforce
Technology alone cannot solve the quantum transition challenge. Organizations must invest in education and workforce readiness. Security teams should receive training in:
- Modern cryptographic architecture
- Post-quantum cryptography concepts
- Cryptographic inventory management
- Quantum risk assessment
Developing internal expertise allows organizations to evaluate new cryptographic technologies and implement secure migration strategies.
AI Accelerating PQC Readiness
Artificial intelligence can help organizations accelerate preparation for post-quantum security without large infrastructure investments. AI-driven cybersecurity platforms can assist with:
Cryptographic Discovery
AI-based scanning tools can automatically identify encryption libraries, certificates, and cryptographic implementations across enterprise environments.
Risk Prioritization
Machine learning analytics can highlight high-risk systems that rely on outdated algorithms.
Automated PKI Management
AI-enabled systems can automate certificate lifecycle management and policy enforcement. Migration Planning.
AI-driven modelling can simulate PQC migration strategies and identify potential compatibility issues. When used responsibly, AI can significantly reduce the operational complexity of cryptographic modernization.
The Emergence of Post-Quantum Cryptography
Recognizing the potential threat of quantum computing, the U.S. National Institute of Standards nd Technology (NIST) launched a global effort to standardize quantum-resistant cryptographic algorithms. The first standardized PQC algorithms include:
- CRYSTALS-Kyber (ML-KEM) – for key encapsulation
- CRYSTALS-Dilithium (ML-DSA) – for digital signatures
- SPHINCS+ – hash-based signature scheme
These algorithms are designed to remain secure against both classical and quantum attacks. (NIST). Organizations should begin planning for the integration of these algorithms into security architectures over time.
Timelines / Maturity
Organizations should align with NIST transition milestones and initiate migration immediately, adopt hybrid cryptography in the near term, deprecate legacy algorithms by 2030, and complete PQC transition by 2035, depending on data sensitivity and system complexity (NIST).
Path Forward: Building a Quantum-Resilient Security Strategy.
Quantum computing represents one of the most transformative technological advancements of the coming decade. While the technology promises breakthroughs in scientific research, artificial intelligence, and materials science, it also introduces significant challenges for modern cryptography.
The potential arrival of cryptographically relevant quantum computers means that organizations must begin preparing for a transition toward quantum-safe security architectures. By strengthening cryptographic governance, adopting modern encryption standards, training cybersecurity teams, leveraging AI-driven security analytics, and monitoring the evolution of post-quantum cryptography, organizations can gradually build resilience against future quantum threats.
With quantum error correction advancing faster than expected, “Q-Day” (the point quantum computers can break modern encryption) is being pulled forward in estimations, driving the immediate, enterprise-wide adoption of post-quantum cryptography (PQC).
As discussed above, quantum resilient cryptographic implementations are still maturing in commercial products. Organizations should adopt a structured, phased transition, starting with crypto discovery, followed by hybrid (classical + PQC) adoption, and ultimately full migration to NIST standardized PQC algorithms such as ML-KEM and ML-DSA (NIST).
The transition to post-quantum security will not occur overnight. However, proactive planning today will ensure that digital systems remain secure even as the next computing revolution unfolds. Early prioritization of quantum-safe key exchange and long-lived data protection will define organizational readiness, as cryptographic agility becomes a critical security capability in the PQC era.
Fayyaz Ahmed
References:
- Live Science, “IBM unveils two new quantum processors, including one that offers a blueprint for fault-tolerant quantum computing by 2029,” 2024. . Available: https://www.livescience.com/technology/computing/ibm-unveils-two-new-quantum-processors including-one-that-offers-a-blueprint-for-fault-tolerant-quantum-computing-by-2029
- The Quantum Insider, “Google researcher lowers quantum bar to crack RSA encryption,” May 24, 2025. . Available: https://thequantuminsider.com/2025/05/24/google researcher-lowers-quantum-bar-to-crack-rsa-encryption/
- Palo Alto Networks, “What is Q-Day?” 2024. . Available: https://www.paloaltonetworks.com/cyberpedia/what-is-q-day
- The Economic Times, “Q-Day may arrive within 3 years, warns IonQ CEO at World Economic Forum Davos,” 2024. . Available: https://economictimes.indiatimes.com/news/international/global-trends/q-day-may-arrive-within 3-years-warns-ionq-ceo-at-world-economic-forum-davos/articleshow/127039283.cms
- IBM Research, “NIST PQC standards and the future of cryptography,” 2024. . Available: https://research.ibm.com/blog/nist-pqc-standards
- National Institute of Standards and Technology (NIST), “NIST releases first 3 finalized post quantum encryption standards,” Aug. 2024. . Available: https://www.nist.gov/news events/news/2024/08/nist-releases-first-3-finalized-post-quantum-encryption-standards
- National Institute of Standards and Technology (NIST), Transition to Post-Quantum Cryptography Standards, NIST IR 8547 (Initial Public Draft), November 2024. Available: https://nvlpubs.nist.gov/nistpubs/ir/2024/NIST.IR.8547.ipd.pdf
- Photo by Vishal Bansal on Unsplash