At the recent Fiber Connect 2026 conference, Michio Kaku, a professor at the City University of New York, predicted that quantum computers would be able to break the current encryption on digital telecom networks within three years. Other experts don’t think it will be that soon, but there is almost universal agreement that it will happen sometime in the 2030s.

There are various types of encryption used in broadband networks. Most voice, text, and data transmitted across networks use symmetric encryption, such as the AES (Advanced Encryption Standard). The vast majority of this encryption uses AES-128, which uses a 128-bit encryption key. AES-256 uses a 256-bit encryption key and is mostly used to transmit things like top-secret military data or for long-term data storage of important data.

Carriers use public-key encryption when handing data between carriers on the web. This generally means using the older cryptography method, RSA (Rivest-Shamir-Adleman), or the newer ECC (Elliptic Curve Cryptography).

It’s expected that quantum computers will first be able to crack public-key cryptography like RSA and ECC. Quantum computers will have a bigger challenge cracking symmetrical encryption. It’s all going to depend on the strength of the quantum computers. For example, scientists calculate that a quantum computer with 10,000 qubits could crack ECC encryption, but it would take 1,000 days to do so. But a larger computer with 26,000 qubits could crack ECC encryption in a day. The most intense forms of encryption might only be cracked by a quantum computer with 100,000 qubits.

There are still breakthroughs needed for quantum computers to have the power to reasonably decrypt the most common forms of encryption. Today, there is a high level of errors introduced inside the quantum computer, and scientists are working to lower the error rate. The challenge of operating a quantum computer also increases in complexity as the number of qubits is increased. There are working quantum computers in labs with as many as 6,100 qubits, but none of these is working well enough to be used for widespread decryption.

The good news is that there are ways to defeat decryption by quantum computers. The term post-quantum encryption is being used to describe algorithms and techniques specifically designed to block decryption by quantum computers. Quantum computers function best by being able to simultaneously process large numbers of calculations, which makes them perfect for figuring out encryption techniques. Post-quantum algorithms use complex algebraic structures like lattices and hash functions to confound a quantum computer. The math problems used in the encryption are designed to be too difficult for quantum computers to solve.

The computer world has been working on post-quantum computing and should be able to fend off quantum computers when the time comes. While that is comforting, there is still some bad news. Bad actors have been hacking companies and scraping data off the web to store and wait for the day when quantum computers can decrypt the data. This is being referred to as “harvest now, decrypt later”, and the folks doing that figure there is a lot of encrypted data today that will still be relevant a decade from now. That might mean things like banking and medical records or corporate secrets that can be damaging if ever known by bad actors. This “harvest now” mindset might explain many of the cases where companies have been hacked with no obvious bad results.

The bottom line is that quantum computers are going to get good enough to decrypt current encryption techniques. Most large quantum computers are still in labs and not readily available to the public. Computers and networks are being readied with new post-quantum encryption techniques that should be able to thwart real-time data hacking. The biggest danger from quantum computers might be the ability to decrypt the mountains of stored data that have been encrypted using today’s algorithms.