Q-DAY: Quantum computing could threaten modern encryption

Q-Day is described as the moment advanced quantum computers can break widely used encryption, and experts and firms report developments that may bring that possibility closer.

Q-Day is described as the moment a quantum computer can break widely used digital encryption. The concept was highlighted in a Saxo Bank prediction and discussed by technology experts. Quantum computers use qubits and quantum mechanics to solve some problems very differently from classical machines. Several companies and governments are publicly advancing quantum research and funding national programmes. Key points: - Q-Day is reported as the point when quantum processors could defeat current encryption, with potential impacts on confidentiality and authentication for emails, banking and some cryptographic assets. - Security agencies and experts warn of a ‘harvest now, decrypt later’ approach, and GCHQ reported an operation called Salt Typhoon that collected encrypted data since at least 2021. - Public estimates place roughly 100–200 quantum computers worldwide, with reporting that many are located in China. - Industry developments cited include IBM’s stated target for a fault-tolerant machine by 2029, Microsoft’s comment that breakthroughs are ‘years, not decades’, and Google’s Willow demonstration of a problem solved rapidly. - Analysts and governments are investing in quantum technologies, and McKinsey’s analysis and the UK’s National Quantum Technologies Programme (with about £2.5 billion noted) were referenced. Summary: Experts report that sufficiently powerful quantum computing could weaken widely used encryption and affect data confidentiality and authentication. Development timelines vary across researchers and companies, and the timing of any widely effective decryption capability is undetermined at this time.