On 31 August 2026, the Centre for Development of Telematics (C-DOT) — the telecom R&D centre of the Department of Telecommunications — unveiled 14 indigenous quantum products at its 43rd Foundation Day in New Delhi, spanning Quantum Key Distribution (QKD) and Post-Quantum Cryptography (PQC).
Before the product list, the problem they exist to solve.
The threat, stated precisely
Most encryption securing the internet today rests on mathematical problems that are hard for classical computers — factoring very large numbers, or computing discrete logarithms. RSA and elliptic-curve cryptography are built on that hardness.
A sufficiently large quantum computer breaks both. Shor's algorithm, running on quantum hardware, factors large numbers and solves discrete logarithms efficiently. No such machine exists at the required scale today. But the threat is already live, and the reason is the part candidates miss.
"Harvest now, decrypt later." An adversary can intercept and store encrypted traffic today, and decrypt it years later when a capable quantum computer exists. For information with a long secrecy life — diplomatic cables, defence plans, intelligence, personal medical and financial records — the data being transmitted today is already at risk from a machine that does not yet exist. That is why migration is urgent now rather than when the hardware arrives.
The two answers, which are not the same thing
This distinction is the single most examinable content in the topic, and the two approaches are frequently conflated.
| Quantum Key Distribution (QKD) | Post-Quantum Cryptography (PQC) | |
|---|---|---|
| Security rests on | Laws of physics | Mathematical hardness believed to resist quantum attack |
| Hardware needed | Specialised quantum hardware — photon sources, detectors, dedicated fibre | Ordinary classical computers — it is software |
| Solves | Key exchange only | Encryption, signatures and key exchange |
| Deployment | Point-to-point over limited distance; infrastructure-heavy | Software upgrade, deployable everywhere |
| Eavesdropping | Detectable — measurement disturbs the quantum state | Not detectable; relies on the problem being hard |
QKD's principle is genuinely elegant: quantum states cannot be measured without disturbance, and cannot be copied — the no-cloning theorem. So an eavesdropper on the key exchange necessarily leaves evidence. Security comes from physics rather than from an assumption about what an adversary can compute.
QKD's limitation is equally real: it needs dedicated hardware and fibre, works over limited distances without trusted relays, and secures only the key exchange, not the bulk data.
PQC is the practical mass solution. It is classical cryptography using problem families — lattice-based, hash-based and others — believed hard even for quantum machines. Because it is software, it can be deployed across existing networks. The US National Institute of Standards and Technology (NIST) has standardised PQC algorithms, and the C-DOT products explicitly incorporate them.
A serious national posture uses both, which is exactly what these fourteen products represent.
The product line
On the QKD side:
- Q-AKSHAY CD — a compact 1U fibre-based QKD system using Coherent One Way (COW) and Differential Phase Shift (DPS) protocols.
- Q-AKSHAY MD — a QKD system on the Measurement Device Independent (MDI) protocol, which removes vulnerabilities arising from the detectors themselves. MDI matters because several practical attacks on QKD have targeted the detector, not the physics — closing that class of attack is a genuine advance.
- C-SPD — a Single-Photon Detector, a critical sub-module.
- C-RD — a wideband RF driver for intensity and phase modulators.
On the PQC side, graded by throughput and use:
| Product | Throughput | Layer / role |
|---|---|---|
| Q-SETU | up to 80 Mbps | Layer 3 quantum-safe encryptor |
| Q-VIKRAM | up to 1 Gbps | Defence-grade Layer 2/3 encryptor |
| Q-MAHASETU | up to 40 Gbps | Commercial-grade Layer 2/3 encryptor |
| Q-AMOGH | up to 200 Gbps | Layer 1 optical encryptor |
| Q-DARSHAN | — | Quantum-safe video IP phone |
All incorporate NIST PQC algorithms.
Notice what the range implies. A 200 Gbps optical encryptor and a video IP phone are the two ends of the same problem: quantum-safe security must work on a backbone optical link and on a desk telephone. Building both, plus the sub-modules — a single-photon detector and an RF driver are components, not products — indicates an attempt at a complete indigenous stack rather than a demonstration.
The indigenisation argument is sharper here than in most fields. Cryptographic equipment is the one category where importing is most obviously self-defeating: a device that protects your secrets, designed and built by someone else, is a trust assumption about that someone else. That is the entire case for C-DOT building this domestically, and it connects to the broader security material in the NDA general knowledge syllabus.
The wider national frame: the National Quantum Mission, approved in 2023 under the Department of Science and Technology, covers quantum computing, communication, sensing and materials — the umbrella under which this work sits.
🔑 Revision block
The event. 31 August 2026 — C-DOT, the R&D centre of the Department of Telecommunications, unveiled 14 indigenous quantum products at its 43rd Foundation Day, across QKD and PQC.
The threat. Today's encryption (RSA, elliptic-curve) rests on factoring and discrete logarithms being hard for classical computers. Shor's algorithm on a large enough quantum computer breaks both.
Why it is urgent now — "harvest now, decrypt later". An adversary can store encrypted traffic today and decrypt it years later. Data with a long secrecy life is already at risk from a machine that does not yet exist.
QKD. Security from the laws of physics — measuring a quantum state disturbs it, and the no-cloning theorem forbids copying, so eavesdropping is detectable. Needs specialised hardware and fibre, works over limited distance, and secures the key exchange only.
PQC. Classical software cryptography using problem families (lattice-based, hash-based) believed hard even for quantum computers. Runs on ordinary computers, deployable across existing networks, covers encryption, signatures and key exchange. NIST has standardised PQC algorithms. PQC needs no quantum hardware — the commonest misconception.
QKD products. Q-AKSHAY CD — compact 1U fibre QKD on COW and DPS protocols · Q-AKSHAY MD — Measurement Device Independent (MDI) protocol, closing detector-targeted attacks · C-SPD — single-photon detector · C-RD — wideband RF driver.
PQC products. Q-SETU 80 Mbps (Layer 3) · Q-VIKRAM 1 Gbps (defence-grade, Layer 2/3) · Q-MAHASETU 40 Gbps (commercial, Layer 2/3) · Q-AMOGH 200 Gbps (Layer 1 optical) · Q-DARSHAN — quantum-safe video IP phone. All use NIST PQC algorithms.
What the range shows. From a 200 Gbps optical backbone encryptor to a desk video phone, plus sub-modules — an attempt at a complete indigenous stack, not a demonstration.
Why indigenisation matters most here. A device that protects your secrets, built by someone else, is a trust assumption about that someone else.
The umbrella. National Quantum Mission, approved 2023, under the Department of Science and Technology — computing, communication, sensing, materials.
🎯 Practice MCQs
Q1. Quantum Key Distribution derives its security from: (a) the laws of physics (b) very long keys (c) mathematical hardness (d) network isolation → (a) — measurement disturbs a quantum state.
Q2. Post-Quantum Cryptography requires: (a) ordinary classical computers (b) quantum computers (c) dedicated optical fibre (d) single-photon detectors → (a) — it is software.
Q3. The algorithm that would break RSA on a large quantum computer is: (a) Shor's algorithm (b) Grover's algorithm (c) Dijkstra's algorithm (d) RSA-2048 → (a).
Q4. 'Harvest now, decrypt later' describes: (a) storing encrypted traffic today for decryption when quantum computers mature (b) compressing data before storage (c) key rotation policy (d) delayed message delivery → (a).
Q5. C-DOT functions under which department? (a) Telecommunications (b) Science and Technology (c) Electronics and IT (d) Defence Production → (a).
Q6. The no-cloning theorem states that: (a) an unknown quantum state cannot be copied (b) qubits cannot be measured (c) photons cannot travel in fibre (d) keys cannot be reused → (a).
Q7. Q-AMOGH provides quantum-safe encryption at: (a) up to 200 Gbps at Layer 1 (b) 80 Mbps at Layer 3 (c) 1 Gbps at Layer 2/3 (d) 40 Gbps at Layer 2/3 → (a) — Q-MAHASETU is the 40 Gbps commercial product.
Q8. The Measurement Device Independent protocol in QKD addresses vulnerabilities arising from: (a) the detectors (b) the optical fibre (c) the key length (d) the operating system → (a).
Q9. The defence-grade quantum-safe encryptor among C-DOT's products is: (a) Q-VIKRAM (b) Q-SETU (c) Q-DARSHAN (d) Q-AKSHAY CD → (a), at up to 1 Gbps.
Q10. The body whose Post-Quantum Cryptography algorithms these products incorporate is: (a) NIST (b) ITU (c) IEEE (d) ISO only → (a) — the US National Institute of Standards and Technology.
Q11. A principal practical limitation of QKD is that it: (a) secures only key exchange and needs dedicated hardware over limited distances (b) cannot detect eavesdropping (c) requires quantum computers (d) works only over satellite → (a).
Q12. The National Quantum Mission was approved in: (a) 2023 (b) 2018 (c) 2020 (d) 2026 → (a), under the Department of Science and Technology.
📋 How this gets asked (PYQ pattern)
Quantum-technology questions have settled into four shapes. The QKD-versus-PQC item — which relies on physics and which on mathematics, and which needs quantum hardware; the claim that PQC requires a quantum computer is the standard false statement. The algorithm item — Shor's for factoring against Grover's for search, and what each threatens. The organisation item — C-DOT under the Department of Telecommunications, against the National Quantum Mission under DST and IndiaAI under MeitY. The principle item — the no-cloning theorem and why eavesdropping is detectable.
The fresh 2026 hook is the 14-product line, particularly the throughput ladder from Q-SETU (80 Mbps) to Q-AMOGH (200 Gbps), and the MDI protocol product. As always, we describe the recurring pattern, not any exact past question.
Preparing for the NDA? Quantum security is a topic where one clean distinction — physics-based QKD versus mathematics-based PQC — answers most of what is asked. Build the base with our NDA general knowledge notes, follow the daily NDA current affairs, and train with our ex-officer faculty in the upcoming Cavalier courses in Delhi.
✍️ Written by Col D.N. Sharma — Defence studies & technology faculty at The Cavalier. Reviewed by the Cavalier Faculty Desk. The Cavalier, founded by ex-Army officers, has trained NDA/CDS/SSB aspirants since 2001 (Facebook · YouTube).
Source: PIB / Ministry of Communications, 31 August 2026. Cryptographic concepts cross-verified with independent sources.