Quantum Computers: Can They Really Shatter Blockchain?

Understanding the Core Vulnerability

A blockchain is like a digital record. There is a chain of “blocks” that each hold transaction data. To add a block, computers use proof-of-work or other similar methods to solve hard puzzles.

Cryptography is what keeps things safe. Bitcoin, for example, uses the elliptic curve digital signature algorithm (ECDSA). This makes both public and private keys. Private keys sign transactions to show who owns them without giving away the key.

Everything changes with Shor’s algorithm, which was made in 1994. It can quickly break down big numbers on a quantum computer. That’s not good for systems like RSA and ECDSA, which rely on math that is hard to factor.

If a quantum computer can run Shor’s algorithm well, it could get private keys from public ones. That means taking money or making up transactions.

Is the Threat Real and Imminent?

Recent developments show progress, but not a full break yet. A Federal Reserve study from 2025 said that quantum tech could make Bitcoin’s old transactions public, which would expose private information.

A study led by Google cut the number of qubits needed to break ECC crypto to less than 3,000, making it 20 times easier than before. China even used quantum to break 22-bit RSA encryption, which is a small but real step.

Experts say, though, that a full threat to blockchain could take decades. Current quantum computers don’t have the stable qubits they need—thousands or millions for real attacks. River Financial says that Bitcoin is not in any immediate danger for the next ten years.

I think that even though the risk seems far away, it could be expensive to ignore it. One Yahoo Finance article says that panic could hurt the crypto markets before any real break. The tech world needs to get ready now, objectively.

Paths to Quantum-Resistant Blockchains

There is still some hope. Some projects work on “post-quantum” cryptography. These use algorithms like hash-based or lattice-based ones, which are hard for even quantum computers to work with.

For example, Quantum Resistant Ledger (QRL) makes its blockchain strong enough to handle quantum attacks from the very beginning. Quranium wants a Layer 1 with adaptive security that can handle 10,000 transactions per second without any problems.

The communities around Bitcoin and Ethereum talk about updates. Moving to quantum-safe signatures could keep them safe, but it would take time and agreement.

I see this as a chance for growth as an analyst. Because blockchain is decentralized, it can make changes that centralized systems might not be able to. To stay ahead, you need to mix new ideas with caution.