Quantum computing threatens today's cryptography while quantum communication offers a remedy. Discuss India's preparedness in light of the National Quantum Mission.

Quantum computers could break public-key systems like RSA and ECC, which protect banking, government and defence traffic [3]. The National Quantum Mission (NQM) has ₹6,003.65 crore for 2023–31 and is run by DST [4]. It responds through quantum communication and quantum-safe cryptography. India's preparedness is promising but uneven.

Threat and remedy

• Harvest now, decrypt later: adversaries can store encrypted data today and decrypt it once quantum machines mature. Secrets that must stay hidden for years are already exposed.
• Quantum Key Distribution (QKD): keys travel on single photons. Any eavesdropping raises the error rate (QBER), so it can be detected.
• Post-Quantum Cryptography (PQC): new maths-based algorithms that run as software on existing systems.

Preparedness: strengths

• Mission design: NQM has a Quantum Communication Thematic Hub. It targets satellite QKD over 2,000 km between Indian ground stations [4].
• Fibre networks: a 1,000 km QKD network has been built on QNu Labs' indigenous technology [5].
• Free-space step: QNu Labs, BISAG-N and IIT Gandhinagar ran a 5.56 km free-space link with QBER below 5% [1]. It paired Armos QKD hardware with Vedic Kavach PQC software [1].
• Defence uptake: QNu Labs supplied 25 QKD systems to the Indian Navy [6].
• Policy: MeitY and CERT-In released a quantum-readiness whitepaper [3]. A Task Force guides PQC migration and certification, and C-DOT has built QKD and PQC solutions [2].

Preparedness: gaps

• Scale: 5.56 km is far from 2,000 km, and the trial ran only at night [1]. Its key rate of 230–260 bps means QKD carries keys, not data [1].
• Fragmentation: DST, MeitY, DoT, DRDO and DoS each build separately [2]. This risks systems that cannot work together and money spent twice.
• Advisory, not binding: no ministry has a deadline to migrate its systems.
• Inherent limits: QKD still needs classical authentication and physically guarded trusted nodes.

Way forward

• A cryptographic inventory, then dated sector-wise PQC migration, starting with defence, power and banking.
• The Task Force as the single standards and certification body, with shared test beds under the Communication Hub.
• A joint ISRO–NQM plan for a quantum satellite payload.

India has moved from laboratory demonstrations to field links and long fibre networks. A hybrid model can turn this momentum into secure, sovereign digital infrastructure: PQC for every system, with QKD added on critical links. This would advance Atmanirbhar Bharat and SDG 9 (resilient infrastructure).