What Is Post-Quantum Cryptography ?

Post-quantum cryptography (PQC) is new cryptography designed to stay secure even when large, powerful quantum computers exist.

Today’s encryption mostly uses:

• RSA
• ECC (Elliptic Curve Cryptography)
• Diffie–Hellman

These are strong against normal computers, but not strong enough against future quantum computers.

Why Current Computers Can’t Break Today’s Encryption

Modern encryption depends on math problems that are extremely hard for regular computers to solve.
Examples:

• RSA relies on the difficulty of factoring huge numbers.
• ECC relies on the difficulty of solving elliptic curve problems.

With today’s computers, breaking these would take thousands to millions of years, making them effectively safe.

Why Quantum Computers Could Break Them

Quantum computers work differently. They use quantum physics to process information in ways normal computers cannot.
One key quantum algorithm is:

• Shor’s Algorithm — can factor large numbers and break RSA/ECC extremely fast once a large quantum computer exists.

This is why future quantum computers could break encryption that is secure today.

How Many Years Until Quantum Computers Can Break Encryption?

There is no exact answer, but most experts estimate:

• 10 to 20 years is a commonly mentioned range
• some believe it could be sooner, others say it might take longer

Even though the timeline is uncertain, the risk is real enough that governments and companies are preparing now.

A major concern is “harvest now, decrypt later”: attackers can store encrypted data today and wait for quantum computers to break it in the future.

Why Post-Quantum Cryptography Matters

Quantum computers are advancing

They are not powerful enough yet, but progress is steady.

Some data must remain secure for decades

Examples:

• medical records
• personal information
• financial data
• government documents

Changing encryption takes a long time

Updating software, hardware, servers, and devices worldwide is a huge task.

How Do We Move to Post-Quantum Cryptography?

Find where encryption is used

List systems such as:

• websites
• apps
• devices
• servers
• cloud services

Adopt the new PQC standards

NIST has selected new quantum-safe algorithms:

• Kyber — secure key exchange
• Dilithium — digital signatures
• FALCON — digital signatures
• SPHINCS+ — digital signatures

These are being built into new browsers, systems, and hardware.

Use hybrid encryption for now

During the transition, systems often combine:

• current algorithms (like ECC), and
• PQC algorithms (like Kyber)

This keeps systems secure today and in the future.

Update systems as vendors add PQC

Over time, PQC support will appear in:

• servers
• operating systems
• VPNs
• cloud platforms
• IoT devices

Stay flexible (cryptographic agility)

Make sure your systems can switch to new algorithms without large rewrites.
Cryptography evolves, and flexibility makes updates easier.

Quantum computers may still be 10–20 years away from breaking today’s encryption, but the transition to new cryptography takes years.
Preparing now protects long-term data and avoids future problems.