First quantum-safe Bitcoin transaction happens with no protocol upgrades needed

First quantum-resistant transaction mined on Bitcoin

The first post-quantum secure Bitcoin transaction was successfully mined this week. It was created by the Starknet Foundation and does not require any changes to the core Bitcoin protocol.

Damian Chen, vice president of growth at the Starknet Foundation, announced the milestone at the Bitcoin Asia conference in Hong Kong on Thursday. He stated that the transaction worked without soft forks, hard forks, or core protocol upgrades.

How the transaction works

The method was developed by StarkWare researcher Avihu Levy. Normally, Bitcoin transactions wait in a public queue before being confirmed. During this time, they can expose cryptographic details that a powerful quantum computer could use to steal funds.

Levy's method generates millions of possible signatures until it finds one with a specific structure that hides vulnerable material while waiting in the queue. This process is called "signature grinding." It takes hours to complete for a single transaction, but the heavy computing cost helps protect against quantum attacks.

Official source: Starknet Foundation

Chen described the event as a "monumental moment" for Bitcoin security. He explained that the new method, dubbed "QSB," adds a hash authorization layer. This means that even if an attacker has a user's private key or can derive it from the public key, they still cannot move the funds.

Because regular Bitcoin nodes do not yet recognize this new transaction format, the transaction could not go into the public mempool. Instead, it was sent directly to MARA's Slipstream mining service, which accepted and mined the block.

Why this matters for Bitcoin security

Quantum computers are expected to become powerful enough to break current Bitcoin encryption at some point. While some developers argue that current quantum computers are not yet advanced enough to pose an immediate threat, others warn that the technology could improve quickly, similar to advances in artificial intelligence.

Chen noted that the main question is not when quantum computers will arrive, but how ready the network and its users will be when they do. This transaction shows that existing Bitcoin holdings can be secured without waiting for a network-wide upgrade.

What is still unclear

It remains unclear whether other miners will adopt the Slipstream service or integrate this signature grinding method into standard operations. Additionally, ordinary Bitcoin nodes currently reject this non-standard transaction format, meaning the method relies on willing miners to process these blocks.

Sources

• Bitcoin Magazine