Quantum Computers: Is Bitcoin in Danger?

Quantum computers and Bitcoin

A quantum computers' development regularly raises the question: is Bitcoin in danger? If a quantum computer were to break Bitcoin's cryptography, the entire system would collapse. But how realistic is this threat in 202

How could quantum computers threaten Bitcoin?

1. Breaking ECDSA signatures

Bitcoin's Elliptic Curve Digital Signature Algorithm (ECDSA) cryptography is used. A sufficiently powerful quantum computer could, with Shor's algorithm theoretically extract the private key from the public key:

• This would enable spending other people's Bitcoins
• Particularly vulnerable are addresses whose public key is visible on the blockchain (old P2PK format, reused addresses)
• Satoshi's ~1.1 million BTC is in such an old format

2. SHA-256 hash weakening

A Grover's algorithm speeds up hash search – but this is less critical:

• It would make mining more efficient but wouldn't break it
• The difficulty adjustment would compensate

Where does quantum technology stand?

The current situation

• Google Willow (2024): 105-qubit chip that demonstrated "quantum supremacy" in specific tasks
• IBM Condor: 1,121-qubit processor
• Breaking Bitcoin's ECDSA would require an estimated 4,000-13,000 logical qubits (fault-tolerant qubits)
• Current machines use "noisy" qubits – the number of logical qubits is orders of magnitude lower

Time Estimates

Expert estimates vary:

• Optimistic (concerned): Breaking cryptography may be possible within 10-15 years
• Conservative: 20-30+ years, if it's even possible at the required scale
• NIST (US National Institute of Standards and Technology): The dangerous period could begin around 2035

Bitcoin's Defense

Quantum-Resistant Cryptography

A NIST finalized in 2024 the first quantum-resistant cryptographic standards:

• CRYSTALS-Dilithium: Digital signature (lattice-based)
• CRYSTALS-Kyber: Key exchange
• SPHINCS+: Hash-based signature

The Bitcoin community is planning the transition to post-quantum cryptography :

• Introducing a new quantum-resistant signature scheme via soft fork
• The Taproot upgrade paved the way for such extensions
• The migration will take years – but there's time

Immediate Defense

• Don't reuse addresses: If you only send from an address once, the public key is visible for a shorter time
• P2TR (Taproot) addresses: The latest address format provides better protection
• Cold storage: As long as you don't spend, the public key doesn't appear on the chain

Other Cryptocurrencies and the Quantum Threat

• Ethereum: Vitalik Buterin published a detailed plan for quantum-resistant transition
• QRL (Quantum Resistant Ledger): A blockchain specifically designed to be quantum-resistant
• IOTA: Ternary computing model with quantum-resistant ambitions

The Realistic Assessment

Before panicking, it's important to note:

• Quantum computers don't just threaten Bitcoin – the entire internet security (banks, military, communications) is based on the same cryptography
• If quantum machines reach that level, breaking Bitcoin will be the least of our worries
• Bitcoin developers are working on the solution years ahead of the danger dolgoznak a megoldáson
• The network's consensus mechanism makes it possible to update the cryptography

Summary

Quantum computers don't just threaten real but not immediate threat to Bitcoin. Technology development and the creation of post-quantum cryptography are progressing in parallel. The Bitcoin community has time to prepare – and is actively doing so.

The quantum threat to Bitcoin is like climate change to society: real, long-term, and requires action – but the world isn't collapsing tomorrow.

⚠️ Legal disclaimer: This article is for informational purposes only and does not constitute investment advice. All investment decisions are made at your own risk.