Is Quantum Computing a Threat to Today's Encryption? What Everyone Should Know

Important caveats:

• No quantum computer today is anywhere near powerful enough. Breaking widely used encryption would need a machine with vast numbers of reliable qubits, far beyond current devices.
• Nobody can say precisely when, or whether, such a machine will exist. Estimates vary widely.
• Symmetric encryption, the kind that scrambles the data itself once a connection is set up, is much less affected. Larger key sizes are considered enough.

"Harvest now, decrypt later"

Why worry now? Because attackers can record encrypted data today and store it, planning to decrypt it years later when quantum computers are available. For information that must stay secret for decades, such as state secrets, health records or financial data, the danger exists already.

The solution: post-quantum cryptography

Researchers are developing new methods that run on ordinary computers but rely on maths problems believed to be hard even for quantum computers. This is post-quantum cryptography.

After an eight-year international competition, the US standards body NIST published its first three standards on 13 August 2024:

• ML-KEM (FIPS 203) for establishing secure connections;
• ML-DSA (FIPS 204) for digital signatures;
• SLH-DSA (FIPS 205), a hash-based signature scheme designed as a conservative backup.

In March 2025, NIST also selected a further algorithm, HQC, as a backup for key exchange, based on different mathematics. Further standards, such as one for the Falcon signature scheme, are still being developed.

Questions people ask

Is my WhatsApp chat or UPI payment unsafe today? No. No quantum computer can break today's encryption, and the services you use are expected to move to quantum-resistant methods well before that becomes possible.

Should I change my passwords? Not because of quantum computing. Strong, unique passwords and two-factor authentication matter far more right now.

Is Bitcoin or other cryptocurrency at risk? Some cryptocurrencies rely on the kind of signatures that quantum computers could threaten in future, which is why developers are discussing upgrades.

What this means for you

For ordinary users, the switch will be largely invisible:

1. Keep your phone, browser and apps updated. Major browsers and messaging services are already adding post-quantum protection.
2. Don't panic-buy "quantum-proof" products. Be sceptical of marketing that claims more than the standards provide.
3. Banks and governments are doing the heavy lifting. Organisations are being urged to inventory their systems, find where vulnerable encryption is used and plan migration.

India's National Quantum Mission includes work on secure quantum communication, and agencies around the world are drawing up migration timelines.

The quantum threat to encryption is real, but it is also well understood, and the defence is being built before the attack machine exists. That is a rare piece of good news in cybersecurity.