Fidelity Digital Assets published a research report titled “Bitcoin’s Path to Quantum Resistance” that lays out the technical roadmap for making Bitcoin immune to quantum computing attacks. The verdict: the math works, but the politics might not.
The report concludes that quantum-resistant upgrades through soft forks are technically feasible. The catch is that every proposed solution comes with tradeoffs that would reshape how Bitcoin processes transactions, and convincing a famously fractious community to adopt any single approach remains the tallest hurdle of all.
The quantum threat, translated
Bitcoin currently relies on two digital signature algorithms, ECDSA and Schnorr, to secure transactions. These algorithms work because deriving a private key from a public key is computationally impractical for classical computers.
Quantum computers change the equation. A sufficiently powerful quantum machine running something called Shor’s algorithm could reverse that process, effectively extracting private keys from public keys. That would let an attacker spend anyone’s Bitcoin.
The important qualifier: no such machine exists yet. Fidelity’s report emphasizes that no Cryptographically Relevant Quantum Computers, or CRQCs, capable of breaking Bitcoin’s signature cryptography are currently operational.
The fix exists, but it’s bulky
Post-quantum cryptographic alternatives already exist. Hash-based signature schemes, lattice-based approaches, and other quantum-resistant algorithms have been studied for years. The issue isn’t whether replacement signatures can be built. It’s that they’re significantly larger than what Bitcoin uses today.
Larger signatures mean each transaction consumes more block space. Bitcoin blocks are capped at a certain size, so fatter signatures translate directly into fewer transactions per block.
Fidelity’s report highlights one particularly promising approach: Blockstream’s SHRINCS BIP, which was formalized in 2026. SHRINCS combines stateful and stateless hash-based signatures in a hybrid model designed to optimize both efficiency and security. The stateful component offers better performance but requires users to actively manage cryptographic “state,” essentially tracking which signature keys have been used. A stateless fallback option provides a safety net for users who don’t want to deal with that overhead.
Consensus is the real boss fight
Fidelity’s report identifies social consensus within Bitcoin’s decentralized governance structure as the most formidable barrier to implementing quantum-resistant upgrades.
Bitcoin has no CEO, no board of directors, no one who can simply decree a protocol change. Upgrades require broad agreement among developers, miners, and node operators. Even when the technical community agrees on a solution, deploying it as a soft fork demands careful coordination and widespread adoption.
The report suggests that a credible, approaching quantum threat could accelerate consensus.
Institutions aren’t waiting around
The Bitcoin Security Consortium, established in July 2026, counts Fidelity Digital Assets, BlackRock, and Coinbase among its founding members. The consortium directs funding toward post-quantum security research without directly influencing protocol-level decisions.