First Quantum-Safe Transaction Mined on Bitcoin Mainnet

TEL AVIV — In a breakthrough for post-quantum cryptocurrency security, cryptography firm StarkWare announced that a quantum-safe transaction using its Quantum-Safe Bitcoin (QSB) framework has been successfully mined on the Bitcoin (BTC) mainnet.

The accomplishment marks the first time a quantum-resistant transaction structure has been executed directly on Bitcoin's live production network rather than modeled in academic literature.

Protecting Coins Without Protocol Changes

Bitcoin relies heavily on elliptic curve cryptography for transaction signatures. A sufficiently powerful quantum computer running Shor’s algorithm could theoretically reverse public keys to expose private keys, rendering published public keys vulnerable.

The QSB method, developed by StarkWare General Manager of Applications Avihu Levy, bypasses the need for consensus-level protocol upgrades by attaching a second, hash-based lock alongside the standard signature.

• Signature Grinding: QSB utilizes signature grinding, performing off-chain computational work to find a spending transaction hash that serves as a valid signature without exposing private keys.

• Hash Resistance: Shor’s algorithm does not pose the same structural threat to hash-based functions as it does to elliptic curve functions.

• No Hard Fork Required: Holders can transfer assets into quantum-resistant structures using Bitcoin's existing consensus rules.

"StarkWare’s announcement is significant because it demonstrates something that, until now, many people assumed would require a change to the Bitcoin protocol," said David de Paula Santos Silva, CEO of CyberX. "A Bitcoin holder can now move coins into a quantum-resistant construction using Bitcoin as it exists today."

Current Limitations: Operational Cost and Speed

Despite the technical milestone, industry experts emphasize that QSB represents an optional safety valve rather than an immediate everyday solution.

Because QSB transactions utilize a nonstandard construction, they cannot travel through Bitcoin's standard mempool and must be routed directly to mining pools.

"Think of it as a safety valve, not a cure," stated Katrina Rosseini, visiting fellow at George Mason University's National Security Institute. "The method isn't practical for everyday use yet, but it shows holders have another way to protect certain assets while the ecosystem works toward a broader post-quantum fix."

Network-Level Vulnerabilities Remain

While QSB gives individual holders a path to secure specific outputs, cryptographers caution that it does not resolve systemic risks facing the wider network.

Adam Everspaugh, cryptography expert at Keeper Security, noted that approximately 30% of all issued Bitcoin supply already has public keys exposed on-chain. QSB cannot retroactively protect inactive or abandoned coins from being recovered and dumped by a future quantum adversary.

Additionally, research engineers note that the QSB technique relies on specific legacy quirks within Bitcoin script, meaning the technique cannot easily be ported to other blockchain ecosystems.

Full network resilience will ultimately require decentralized consensus on protocol-level upgrades, defining "Q-day" parameters, and managing legacy unspent transaction outputs. However, QSB dismantles the long-standing assumption that asset holders are completely helpless while awaiting network-wide upgrades.