Quantum Threat on Blockchain: Which Cryptocurrencies Are Truly Safe?

The Ticking Clock: When Will Quantum Computing Truly Break Blockchain?

Let’s be honest: blockchain security relies entirely on cryptographic algorithms. Both Bitcoin and Ethereum depend on the Elliptic Curve Digital Signature Algorithm (ECDSA) to protect your private keys and transactions. But quantum computers are changing the game completely.

Algorithms like Shor’s algorithm could theoretically analyze your public key and compute your private key—an task that would take billions of years on today’s normal computers. Experts warn that this scenario could become a reality between 2028 and 2035, with some researchers even citing earlier 2028.

Bitcoin vs. Ethereum: Who is Better Prepared?

Ethereum is in a much stronger position. Thanks to its flexible governance structure, Ethereum can implement upgrades such as EIP-4337, which facilitate a smoother transition to quantum-resistant cryptography (PQC). Its modular design means new cryptographic algorithms—like Kyber, Dilithium, and SPHINCS+—can be integrated relatively easily.

Bitcoin, on the other hand, is more complicated. The network prioritizes decentralization and immutability, making rapid security upgrades more difficult. Any fundamental change would likely require a hard fork—a potential split in the community, as happened previously with Ethereum Classic in 2016. Achieving consensus on such a drastic measure is a significant challenge for Bitcoin.

The “Harvest Now, Decrypt Later” Problem

Here’s something sinister: attackers are already storing encrypted blockchain data today, intending to decrypt it once quantum computers are powerful enough. This scenario—‘harvest now, decrypt later’—emphasizes that we cannot wait until the threat is actually present.

Even more concerning: about 25% of circulating Bitcoin already exposes public keys, making them vulnerable now. Over time, such weak links—especially in older wallets—could lead to systemic risks.

Why Newer Blockchains Are Better Prepared

Some newer networks, like Solana and Sui, have anticipated this problem. They use EdDSA signature schemes instead of ECDSA, which are structurally better suited for future quantum-resistant upgrades. This demonstrates how emerging blockchains can proactively address security risks.

If you’re considering investing in alternative blockchain ecosystems—whether Bitcoin, Ethereum, or other tokens—you want to ensure your future holdings are also secure. This also applies to lesser-known blockchain tokens focusing on post-quantum cryptography; it’s worth examining their technical architecture before investing in encrypted assets.

What is Post-Quantum Cryptography Really?

Post-quantum cryptography (PQC) refers to algorithms specifically designed to withstand attacks from quantum computers. The US NIST and consulting firms like Deloitte are pushing for widespread adoption of PQC by 2030 to protect critical infrastructure and digital assets.

The good news: these algorithms already exist. The bad news: the industry has not implemented them quickly enough.

The Missing Collaboration

The crypto industry and quantum computing experts are not collaborating sufficiently. This communication gap means security solutions are being implemented more slowly than they should be. Coordination is essential: blockchain developers, researchers, and regulators must work together on PQC migration.

How Attacks Would Actually Work

Quantum computers could undermine security via two routes:

1. Shor’s algorithm directly computes private keys from public keys—ECDSA’s weak point
2. Grover’s algorithm accelerates brute-force attacks on hash functions like SHA-256, which secures Bitcoin’s proof-of-work mining

Both forms of attack could render current cryptographic standards potentially obsolete.

In Conclusion: An Industry at a Crossroads

The quantum threat is real and imminent. But it’s not an unavoidable disaster—if the industry acts now. Ethereum’s flexibility, new blockchain architectures’ proactive design, and advances in PQC offer hope.

What’s needed: proactive measures now, rather than reactive ones later. The question is not if quantum computing will impact blockchain, but when—and whether we are prepared when that moment arrives.