The question is no longer whether a quantum computer capable of breaking today’s encryption will exist. Credible estimates from researchers and government agencies now place Q-Day, the moment a cryptographically relevant quantum computer becomes operational as early as 2029. That is three years from now. For most enterprise security teams, three years sounds comfortable. It is not.

Q-Day refers to the point at which a quantum computer will be capable of running Shor’s algorithm at sufficient scale to break RSA and elliptic curve cryptography, the encryption standards that protect the majority of the world’s digital communications, financial transactions, and stored data today. When that moment arrives, the secrecy of every communication ever recorded using current encryption standards becomes retroactively compromised.

The “Harvest Now, Decrypt Later” Threat You Are Already Facing

The most immediate and underappreciated aspect of the quantum threat is that it does not begin at Q-Day. It began years ago.

Nation-state threat actors and there is significant evidence that several are doing this systematically are actively harvesting encrypted communications and data today, storing them in anticipation of the day when they have the computational capacity to decrypt them. Your most sensitive communications from 2024, your proprietary research from 2023, diplomatic cables from 2022: if any of it was intercepted in transit, it will be decryptable on the day a sufficiently powerful quantum computer becomes available.

This means that data with long-term sensitivity national security intelligence, pharmaceutical research, financial trading strategies, personal medical records, legal materials is already effectively compromised for any organisation that has been targeted by a sophisticated state-level adversary. The question is not whether your data will be exposed at Q-Day. It is whether your data has already been collected and is sitting in someone’s storage waiting for Q-Day to arrive.

Where the Timeline Stands in 2026

The 2029 estimate comes from multiple converging sources. IBM, Google, and several government-backed quantum computing programmes have published roadmaps that place fault tolerant, cryptographically relevant quantum computing within a three-to-five year window. China’s publicly announced quantum programmes are tracking a similar timeline. The United States National Security Agency updated its guidance to specifically call out 2030 as the target date by which critical national security systems must have transitioned to post-quantum cryptography.

In practice, this means the enterprise migration window, the time available to assess, plan, and implement post-quantum cryptographic standards across an organisation’s entire technology estate is narrowing rapidly. Most large organisations with complex legacy infrastructure require three to five years to execute a full cryptographic migration. The arithmetic is uncomfortable.

NIST Has Published the Standards, The Migration Has Not Begun

In 2024, the National Institute of Standards and Technology (NIST) finalised the first three post-quantum cryptographic algorithms CRYSTALS-Kyber for key encapsulation, and CRYSTALS Dilithium and SPHINCS+ for digital signatures. These standards are the foundation upon which post quantum migration will be built.

The standards exist. What most organisations have not done is begin the migration. A 2025 survey of Fortune 500 security teams found that fewer than 12% had begun a formal cryptographic inventory the essential first step of identifying where RSA and elliptic curve cryptography is used within their systems. Without knowing where current encryption sits, an organisation cannot plan how to replace it.

What Indian Enterprises Should Do in the Next 12 Months

India’s financial sector, defence infrastructure, and rapidly expanding digital public infrastructure- Aadhaar, UPI, DigiLocker all rely on cryptographic standards that will be vulnerable at Q-Day. The RBI Cybersecurity Framework and the DPDP Act 2023 do not yet explicitly address post-quantum cryptography, but the window for regulatory guidance to emerge ahead of Q-Day is closing.

Pragmatic first steps for Indian enterprise security teams:

• Cryptographic inventory: Identify every system, application, and communication channel that uses RSA or elliptic curve cryptography. This is the prerequisite for everything else and it takes longer than expected.
• Classify data by sensitivity and longevity: Not all data requires immediate post-quantum protection. Data that must remain confidential for more than five years medical records, financial history, proprietary research should be prioritised for early migration.
• Engage your vendors: Cloud providers, networking equipment manufacturers, and software vendors are all on their own post-quantum migration timelines. Understanding their roadmaps is essential before you can set your own.
• Begin piloting NIST-approved algorithms: Several cloud providers and security vendors already support CRYSTALS-Kyber and CRYSTALS-Dilithium in preview. Running a limited pilot now builds organisational familiarity well before the migration becomes urgent.
• Brief your board: Q-Day is a strategic risk, not a technical detail. The board should understand that the three year window is an organisational transformation timeline, not a comfortable horizon.

The organisations that will navigate the quantum transition without crisis are not those that start when Q-Day is announced. They are those that started their cryptographic inventory in 2026.