Fidelity Digital Assets: Bitcoin private keys face future quantum risks

According to Bitcoin.com, Fidelity Digital Assets has released an analysis report indicating that future quantum computers may derive Bitcoin private keys from exposed public keys, threatening asset security. Existing Bitcoin transactions rely on elliptic curve digital signature algorithms or Schnorr signatures, and sufficiently powerful quantum computers running Shor's algorithm could break this cryptographic assumption.

The report evaluates the SHRINCS post-quantum signature scheme as a potential upgrade path—providing a compact 48-byte public key, with state signature sizes ranging from 548 to 4,619 bytes, and a 5,777-byte stateless fallback path to address state loss. However, quantum-resistant signatures will significantly increase transaction data size, consume more block space, reduce network throughput, and drive up transaction fees during congestion. Implementing such upgrades will require new consensus rules (possibly through a soft fork) and broad support from wallets, miners, exchanges, and custodians. In July of this year, Fidelity co-funded a $15 million Bitcoin security program with eight other institutions, covering anti-quantum research.