The Quantum Computing Time Horizon: When Will AI Break Current Encryption?

Your bank balance is encrypted. Your medical records are encrypted. Every private message you've ever sent sits behind layers of encryption designed to keep it safe from prying eyes. But in the coming years, a new type of computer could render all of that protection obsolete in seconds. This isn't science fiction anymore. It's a calculation experts are making right now, and the timeline is far closer than most people realize.

What Quantum Computing Can Actually Do to Encryption

To understand the threat, imagine a traditional computer trying to crack a lock with a trillion possible combinations. It would check each one methodically, one after another. A quantum computer works differently. Instead of checking combinations sequentially, it exploits the bizarre rules of quantum physics to explore many possibilities simultaneously. This parallelism isn't just faster—it's potentially revolutionary.

The encryption protecting most internet traffic today, called RSA and ECC (elliptic curve cryptography), depends on a mathematical problem that would take conventional computers thousands of years to solve. Quantum computers could crack these same problems in hours or days. Recent breakthroughs have shown that fewer than one million physical qubits could break RSA-2048 encryption in less than a week, a 95% reduction from previous estimates of 20 million qubits.

This capability is called breaking encryption at the cryptographic level. It's different from hacking into a system or guessing a password. It's mathematically defeating the protective algorithm itself.

The Timeline: When Exactly Will This Happen?

Here's where the conversation gets urgent. According to the Global Risk Institute's 2025 report, more than half of quantum and cybersecurity experts surveyed estimate at least a 5% likelihood of a cryptographically relevant quantum computer arriving within 10 years, with almost a third indicating a 50% or higher likelihood.

Breaking it down further: By 2034, estimates suggest between a 17% and 34% chance that a cryptographically relevant quantum computer (CRQC) could exist, with that probability increasing to 79% by 2044. U.S. government agencies including NIST and NSA have issued warnings that Q-Day could arrive as early as 2030, particularly if a breakthrough accelerates hardware development.

These aren't distant projections based on vague assumptions. They reflect measurable progress. Google announced its Willow chip in December 2024, demonstrating that adding more error correction actually reduced errors rather than creating more problems, cracking a key challenge in quantum error correction that the field has pursued for almost 30 years.

IBM has announced plans to achieve 200 reliable logical qubits by 2029, capable of performing over 100 million quantum operations.

The consensus among experts is clear: it's no longer a question of if quantum computers will break current encryption, but when.

The Harvest Now, Decrypt Later Threat

Here's a disturbing reality that keeps security experts awake at night: adversaries don't need to wait for quantum computers to become a threat. Attackers can intercept encrypted traffic today and store it for future decryption. When quantum computers mature, that archived data could be decrypted quickly, creating a delayed risk where sensitive information thought secure for decades may be readable overnight.

This is called "Harvest Now, Decrypt Later" or HNDL attacks. Intelligence agencies have warned that this tactic is already underway. Nation-states and sophisticated threat actors are collecting encrypted communications right now with the explicit intent to unlock them when quantum capability arrives.

Your confidential emails from 2020, your financial records, your health information, government communications—all potentially vulnerable if they were intercepted and stored.

This shifts the deadline. Organizations don't need to wait for quantum computers to break encryption to start feeling the impact. They need to protect sensitive data now if that data needs to remain confidential for decades into the future.

What Quantum Computers Will Break Beyond Encryption

The threat extends beyond simple data protection. Digital signatures, which confirm integrity and authenticity, could be compromised if quantum computers can derive private keys, allowing malicious actors to forge signatures that appear legitimate and impersonate trusted software vendors or users without detection.

Think about what digital signatures protect today: financial transactions, software updates, identity verification, legal documents. A breakdown in digital signature security would undermine the trust infrastructure of the entire internet.

Blockchain and cryptocurrency systems, which depend heavily on elliptic curve cryptography, would face similar vulnerability. The consequences would ripple across banking, healthcare, government, and virtually every digital system we depend on.

The Solution Already Exists: Post-Quantum Cryptography

The good news is that the cybersecurity community didn't wait for quantum computers to become a crisis. In August 2024, NIST released its principal post-quantum cryptography standards, specifying algorithms like Module-Lattice-Based Key-Encapsulation Mechanism (ML-KEM), Module-Lattice-Based Digital Signature Standard (ML-DSA), and Stateless Hash-Based Digital Signature Standard (SLH-DSA) that are designed to withstand attacks from quantum computers.

These aren't theoretical solutions. They're finalized, vetted, and ready for deployment. Major technology companies and government agencies have already begun implementation. But here's the challenge: The process of fully integrating new encryption standards across information systems can take 10 to 20 years, partly because companies have to build these algorithms into products and services we use every day.

This creates a critical window. Organizations need to start migrating to quantum-resistant encryption now, even though the threat might be years away. Any data organizations want to keep confidential beyond 2035 needs protection now.

Preparing for the Quantum Era

What should this look like in practice? Security experts recommend several steps. First, organizations need to identify which systems and data are most vulnerable and which data has long-term sensitivity requirements.

Second, they should begin pilot deployments of post-quantum cryptography standards, testing integration with existing systems. Third, they need to plan for what's called "crypto-agility," the ability to quickly swap out encryption methods if needed.

McKinsey's Quantum Technology Monitor 2025 notes that quantum-tech investment grew by nearly 50% in 2024, reaching about $2 billion, as progress in qubit stability and error correction signaled a shift from scaling qubit counts toward building more practical, reliable systems. This acceleration in development is why the timeline keeps compressing.

The reality is sobering but manageable. Quantum computers capable of breaking encryption aren't arriving tomorrow. But the migration to quantum-resistant systems needs to happen soon.

Organizations that delay until certainty arrives will already be too late. The time to prepare isn't when the threat becomes obvious. It's now, while there's still room to implement solutions methodically and thoroughly.

Fast Facts: Quantum Computing and Encryption Explained

What is a cryptographically relevant quantum computer, and why does it matter?

A cryptographically relevant quantum computer (CRQC) is a quantum system capable of breaking RSA and ECC encryption in reasonable time. It matters because these algorithms protect virtually all sensitive data online. Once a CRQC exists, unprotected encrypted data becomes vulnerable to decryption in hours or days.

How soon could quantum computers actually break current encryption?

Most experts estimate a cryptographically relevant quantum computer could arrive in the 2030s, with government agencies warning it could happen as early as 2030. A 17% to 34% chance exists by 2034, rising to 79% by 2044. However, the real deadline is now, since adversaries are already storing encrypted data for future decryption.

What are post-quantum cryptography standards, and are they ready to deploy?

Post-quantum cryptography standards are encryption algorithms designed to resist quantum computer attacks. NIST finalized three standards (ML-KEM, ML-DSA, and SLH-DSA) in August 2024. They're ready for deployment today, though full implementation across systems will take 10 to 20 years because of integration complexity.