StarkWare Executes First Quantum-Safe Bitcoin Transaction on Mainnet

This demonstration marks a significant step in securing Bitcoin against potential quantum computing vulnerabilities without altering existing consensus rules.

• StarkWare executed the first quantum-safe Bitcoin transaction on August 26, 2026, using the Quantum-Safe Bitcoin (QSB) method.
• The transaction involved sending 3.1 BTC using hash-based signatures, making it resistant to forgery by quantum computers.
• No protocol changes were required, as the transaction was mined in block 964,199, addressing concerns about future coin paralysis.

• Bitcoin's security relies on elliptic-curve cryptography, which quantum computers could theoretically break, risking forgery of signatures.
• Prior to this, quantum resistance was thought to require protocol changes, such as a soft fork, to be effective.
• The QSB method was developed as an interim solution, allowing custodians to protect assets without waiting for broader network upgrades.

On August 26, 2026, StarkWare successfully demonstrated the first quantum-safe Bitcoin transaction on the mainnet, a significant milestone in cryptocurrency security. This transaction, executed by StarkWare researcher Avihu Levy, utilized the Quantum-Safe Bitcoin (QSB) construction, which relies on hash-based signatures instead of traditional elliptic-curve cryptography. The choice of hash-based signatures is crucial because they are believed to be resistant to the types of attacks that quantum computers could launch using Shor's algorithm.

The transaction involved sending 3.1 BTC, which was mined in block 964,199. Notably, this was achieved without requiring any changes to Bitcoin's consensus rules, such as a soft fork. This is a critical point because many in the cryptocurrency community had previously assumed that making Bitcoin quantum-resistant would necessitate significant protocol changes. The successful execution of the QSB transaction demonstrates that it is possible to enhance security against quantum threats while maintaining the integrity of the existing Bitcoin network.

The QSB method was developed as a passion project by Levy, who published a whitepaper and open-source implementation in April 2026. The implementation was further refined with contributions from StarkWare engineer Tomer Giladi. The transaction was submitted through MARA's Slipstream mining service due to its nonstandard format, which exceeded typical relay policies. This highlights the innovative approaches being taken to navigate the complexities of Bitcoin's existing infrastructure while introducing new security measures.

StarkWare has positioned QSB as a stopgap solution for Bitcoin custodians, allowing them to protect their assets against potential quantum threats without waiting for a global protocol upgrade. However, it is important to note that while QSB provides immediate protection for newly moved coins, it does not retroactively secure existing holdings. StarkWare CEO Eli Ben-Sasson emphasized that a soft fork remains the optimal long-term solution for achieving comprehensive quantum resistance across the Bitcoin network.

The implications of this development are significant, particularly for Bitcoin custodians and high-net-worth individuals who may be concerned about the future of their assets in a world where quantum computing becomes more prevalent. The QSB method offers a practical interim measure, allowing these stakeholders to take proactive steps in safeguarding their investments.

• Bitcoin custodians: They can implement QSB to protect assets against quantum threats.
• High-net-worth individuals: Those holding significant Bitcoin amounts may seek immediate solutions for asset security.
• Cryptocurrency exchanges: They may need to adapt their security protocols to accommodate quantum-safe transactions.

• Adoption rates of QSB among custodians: Increased adoption could signal a shift in how Bitcoin is secured against quantum threats.
• Discussions around Bitcoin protocol upgrades: Ongoing conversations about soft forks or other upgrades could indicate the community's response to quantum risks.
• Market reactions to quantum computing advancements: Observing how the market reacts to developments in quantum technology will provide insights into future Bitcoin security measures.