The dramatic capture of Nicolás Maduro through digital disruption rather than battlefield combat has underlined a stark reality of modern conflict: cyber power can destabilise regimes without firing a shot. Yet this episode may prove modest when compared to the far greater disruption looming on the horizon — “Q-Day”, the moment when quantum computers become powerful enough to break today’s encryption standards and upend the foundations of global digital security.
What is Q-Day and why it matters
Q-Day refers to the point at which quantum computers can reliably crack widely used cryptographic systems such as RSA and Elliptic Curve Cryptography (ECC). These algorithms currently secure banking transactions, military communications, health records, satellites, power grids, and the internet itself. Once broken, the confidentiality and integrity of digital systems collapse simultaneously across sectors.
This threat is not theoretical. Adversaries are already executing “harvest now, decrypt later” strategies — siphoning off encrypted data today with the intention of unlocking it once quantum capability matures. Financial records, defence communications, and sensitive personal data are already at risk, even if Q-Day is still a few years away.
From cyber disruption to systemic collapse
A quantum-enabled breach would not resemble a conventional cyberattack confined to one organisation. Its impact would be systemic. Banking networks could be paralysed as encrypted transactions are altered, accounts drained, and payment systems disrupted. Stock exchanges could face manipulation at scale, triggering market crashes and eroding trust in financial institutions.
In defence and strategic domains, the implications are even more severe. Encrypted command-and-control systems, satellite links, and secure communications could be compromised. Adversaries might spoof military signals, disable radar systems, or hijack unmanned platforms, undermining deterrence and national sovereignty without a declared war.
Critical civilian infrastructure would be equally exposed. Hospitals could lose access to patient records or find them altered, directly endangering lives. Power grids, water systems, and telecom networks could be disrupted simultaneously, plunging cities into chaos. The interlinked nature of modern infrastructure means a quantum-enabled attack could cascade rapidly across sectors.
How close is the quantum threat?
The timeline is unsettlingly short. has publicly suggested that a three-year horizon for serious quantum threats is plausible. A recent study by found that 70% of executives expect quantum-enabled cyberattacks within five years, while the remainder believe the window could be as narrow as three.
Despite these warnings, most organisations remain passive, waiting for regulatory clarity or industry-wide signals. This complacency is risky. Quantum research is accelerating, and breakthroughs often arrive earlier than anticipated. Worse, the “harvest now, decrypt later” approach ensures that damage is already being prepared, regardless of when Q-Day formally arrives.
Post-quantum cryptography as the first line of defence
The most urgent response is migration to post-quantum cryptography (PQC) — encryption algorithms designed to resist quantum attacks. This transition must begin before large-scale quantum computers become operational, since waiting until Q-Day would be too late.
Regulators and organisations need detailed PQC migration roadmaps that identify and replace vulnerable cryptographic methods embedded across systems. A critical tool in this process is the Cryptographic Bill of Materials (CBOM), which inventories cryptographic assets, algorithms, and dependencies. Without CBOMs, institutions may not even know where their vulnerabilities lie.
Beyond algorithms: defence in depth
While PQC relies on mathematical resilience, Quantum Key Distribution (QKD) adds a physics-based layer of security by making interception of encryption keys detectable. Used together, PQC and QKD provide a defence-in-depth approach, particularly important for sectors handling sensitive, long-lived data.
India has already taken early steps in this direction. QNu Labs, working with the Indian Army and the Department of Science and Technology’s National Quantum Mission, has demonstrated a 500-kilometre quantum-safe communication backbone using QKD — a signal of India’s intent to prepare for the post-quantum era.
Sector-wise priorities for quantum readiness
The response to Q-Day must be tailored yet coordinated across sectors.
In finance, regulators should mandate PQC adoption in banks, payment networks, and stock exchanges, including quantum-safe protocols for interbank messaging and settlement systems.
In energy and utilities, PQC must be integrated into SCADA systems and grid controls, with redundancy built in to limit cascading failures.
In healthcare, patient data storage and transmission require quantum-safe encryption, alongside secure, long-term backups.
In defence, quantum-safe communications, satellite encryption, and secure command systems must be prioritised to preserve military readiness and deterrence.
Why training and governance matter
Quantum resilience is not just a technical upgrade; it is a governance challenge. Regulators should require organisations to train leadership and staff on quantum risks and mitigation strategies, ensuring preparedness extends beyond IT teams. Scenario-based exercises simulating quantum-enabled attacks can expose vulnerabilities, test response protocols, and build institutional resilience.
Boards and policymakers must treat Q-Day as a strategic risk, comparable to financial crises or military threats. Decisions delayed today could translate into irreversible damage tomorrow.
What is ultimately at stake
The quantum threat is real, imminent, and systemic. Migration to post-quantum cryptography will not only protect data and infrastructure from future quantum attacks but also secure information already being harvested today. The window for action is narrowing rapidly. Preparing for Q-Day is no longer optional — it is essential to safeguarding economic stability, national security, and public trust for decades to come.
What to note for Prelims?
- Q-Day refers to quantum computers breaking current encryption standards.
- RSA and ECC are vulnerable to quantum algorithms.
- “Harvest now, decrypt later” is an active cyber strategy.
What to note for Mains?
- Quantum computing as a national security and economic challenge.
- Need for post-quantum cryptography and regulatory preparedness.
- Role of defence-in-depth approaches like PQC and QKD.
- Governance and capacity-building for emerging technology risks.
