Quantum Computing: A Real Threat to Blockchain Security?

Jakarta, July 22, 2025 – The rapid advancement of quantum computing technology has once again raised global concerns about the security of crypto assets. The primary threat emerges as “Q-Day”—the moment when quantum computers become capable of breaking public-key encryption, the very foundation of blockchain security—draws closer.

1. Global Survey: Corporations on High Alert

The latest research from the Capgemini Research Institute shows that 70% of companies are now preparing post-quantum security strategies for the next five years. Two-thirds of respondents expressed concerns about the “harvest-now-decrypt-later” approach, in which data stolen today could be decrypted when quantum technology reaches full maturity.
Even more alarming, one in six companies predicts that Q-Day will arrive within the next five years (WIRED, TechRadar).

2. Quantum Algorithms and Their Impact on Crypto

Shor’s algorithm has the potential to break public-key encryption methods such as RSA and ECC at exponential speed.
Deloitte warns that approximately 25% of Bitcoin is stored in public addresses, which would become highly vulnerable to quantum attacks.
Meanwhile, a Wall Street Journal report estimates that this threat could materialize in less than a decade.
The implications for blockchain? Catastrophic—if countermeasures are not implemented immediately.

3. The “Harvest-Now-Decrypt-Later” Threat

This strategy has become one of the biggest risks: malicious actors collect encrypted data now with the intent to decrypt it later, once quantum computing resources are adequate.
NIST (National Institute of Standards and Technology) has responded by introducing post-quantum security standards since August 2024, including CRYSTALS-Kyber and Dilithium as initial solutions.

4. The Race to Build Post-Quantum Systems

The technology and academic communities are actively developing multiple approaches, including hash-based and lattice-based cryptography, as well as hybrid systems combining Quantum Key Distribution (QKD) with post-quantum cryptographic protocols.
According to Coinbase, crypto systems are not yet directly impacted, but preparation must start now because the quantum threat is only a matter of time.

5. Who Is Most Vulnerable?

The banking and financial sectors show low readiness, scoring only 2.4 out of 5, according to an ISB Institute survey.
More than 57% of BFSI stakeholders believe that quantum computing will become a major threat within three years.
The CEO of Quantum Security warns:

6. The Countdown to Q-Day

Research by Google Quantum AI reveals that the resources needed to break RSA encryption are 20 times lower than previously estimated, accelerating the timeline of this real threat.
Other studies predict that a significant quantum threat could emerge within 10–20 years—or even sooner—turning mitigation efforts into an urgent race.

Key Takeaways and Strategic Actions

• The Threat Is Real: Quantum computing can break fundamental public-key encryption, jeopardizing blockchain and crypto wallets.

• Immediate Action Required: Migration to post-quantum algorithms must start now.

• Global Collaboration Is Essential: Regulators, financial institutions, and the open-source community must work together.

• Time Is Limited: With only 5–10 years estimated until Q-Day, any delay could be catastrophic.

• Solutions Are Emerging: Quantum-resistant cryptography and QKD provide hope, but global adoption remains limited.

Quantum computing is not just a tech buzzword—it is an existential threat to the cryptographic security that underpins blockchain.
The race toward post-quantum solutions must begin immediately—before Q-Day changes everything.