POST-QUANTUM READINESS
Which blockchains are quantum-ready?
Every major chain relies on signatures a large quantum computer could break. Here is what each one uses, what it plans to switch to, and how far along it is.
| Chain | Signatures today | Post-quantum plan | Status |
|---|---|---|---|
| Bitcoin | ECDSA and Schnorr on secp256k1 | BIP-360 "Pay to Merkle Root" (P2MR, formerly P2QRH): a new output type that hides keys until spent. It adds no post-quantum signatures itself; those are left to a later proposal. Source | Draft BIP |
| Ethereum | ECDSA on secp256k1 (accounts); BLS (validators) | Account abstraction (EIP-8141, considered for the Hegotá upgrade in late 2026) so users can switch signature scheme; hash-based leanXMSS for validators. Core post-quantum work targeted for about 2029. Source | Roadmap |
| Solana | Ed25519 | We found no published protocol-level plan (checked 4 Nov 2026). An opt-in, unaudited Winternitz one-time-signature vault program exists for holding SOL. Source | Opt-in tool only |
| Algorand | Ed25519 (accounts and consensus) | Falcon-1024 (lattice-based, NIST-selected) already signs state proofs. Opt-in Falcon accounts went live on mainnet in November 2025; normal accounts still use Ed25519. Source | Partly live |
| Cardano | Ed25519 | IOG research programme: post-quantum replacements for signatures, key-evolving signatures and the leader-election VRF, plus a published migration strategy. Timelines not final. Source | Research |
| QRL | XMSS (hash-based) | Built post-quantum from the start: XMSS, the IETF-specified hash-based scheme, signs every transaction. Source | Post-quantum by design |
Checked against each project’s own documentation on November 4, 2026.
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Questions
Why are blockchains vulnerable to quantum computers?
Almost every major chain signs transactions with elliptic-curve cryptography (secp256k1 or Ed25519). Shor’s algorithm on a large error-corrected quantum computer could derive a private key from a public key. Hashes and most consensus mechanisms are far less affected.
Is Ed25519 safer than secp256k1 against quantum attacks?
No. Both are elliptic curves of similar size, and both fall to the same quantum algorithm.
What does quantum-ready mean here?
That ordinary users can hold and send funds with a post-quantum signature scheme (such as hash-based XMSS or lattice-based Falcon or ML-DSA), on mainnet. A roadmap or research programme is progress, not readiness.