New quantum-safe Bitcoin transactions cost $200 without a soft fork

A StarkWare researcher has introduced a method for quantum-resistant Bitcoin transactions that works on the live network today, but at an estimated cost of up to $200 per transaction.

In a paper published this week, researcher Avihu Levy outlined the "Quantum Safe Bitcoin" (QSB) scheme, which functions entirely within Bitcoin's existing consensus rules without requiring a protocol upgrade.

The system replaces Bitcoin’s standard ECDSA signatures with hash-based proofs. This security shift requires massive off-chain GPU computation, driving costs from $75 to $200, far above the current average transaction fee of around 33 cents, according to data from yCharts.

Levy frames the high-cost scheme as a "last resort measure" to defend against a sudden quantum computing threat, providing an emergency fallback while more permanent solutions like the BIP-360 proposal remain years from potential activation.

How QSB Works

QSB redesigns transaction security around hash-based proofs, which are considered resistant to the types of attacks from quantum computers that could break today's digital signatures. Instead of signing a transaction with a private key, a user generates a unique mathematical "fingerprint" of the data. While this avoids the vulnerabilities of public-key cryptography, it is computationally intensive, requiring a search through billions of candidates to generate a valid transaction. This process would likely be outsourced to specialized GPU hardware.

Practical Limits and Long-Term Solutions

The QSB method comes with significant practical hurdles. Transactions are complex to create and would likely need to be sent directly to miners, bypassing the normal mempool. Furthermore, they are not compatible with layer-2 solutions like the Lightning Network. This contrasts with the proposed BIP-360, which aims to integrate quantum-resistant cryptography at the protocol level via a soft fork. While BIP-360 is seen as the more scalable long-term solution, its activation timeline is uncertain and could take years, similar to the seven-year journey for the Taproot upgrade. QSB offers an immediate, albeit expensive, alternative if the quantum threat materializes sooner than expected.

This article is for informational purposes only and does not constitute investment advice.