The Hardy Index Quantum readiness benchmark

Guide · Which chains are ready

Which crypto is quantum proof?

Plenty of projects call themselves quantum proof. Here is the independently checked version, and why the phrase itself is worth handling carefully.

The Hardy Index · Reviewed 12 August 2026 · Every claim below carries a primary source.

The short answer

Very few. Most cryptocurrencies still use signatures a quantum computer could eventually break. As of 12 August 2026, the Hardy Index rates 2 of 23 major chains as post-quantum on mainnet today: Quantum Resistant Ledger and Abelian. Quantum proof is a spectrum rather than a badge.

Which cryptocurrencies are quantum proof today?

Only chains whose post-quantum signatures protect every account on mainnet can reasonably be called quantum proof. As of 12 August 2026, the Hardy Index finds two of them among 23 rated chains.

  • Quantum Resistant LedgerQRLHardy 92.0XMSS (stateful hash-based), mandatory for all accounts
  • AbelianABELHardy 84.5Lattice-based post-quantum signatures, mandatory for all transactions

A second group has post-quantum signatures live on mainnet without them being the default. On those chains a holder can opt in today, which is a meaningfully different position from waiting for a roadmap.

  • Nervos CKBCKBHardy 75.5secp256k1 by default; SPHINCS+ available via an on-chain lock script
  • AlgorandALGOHardy 74.5Ed25519 for standard accounts; Falcon for State Proofs and post-quantum transactions
  • SolanaSOLHardy 54.5Ed25519 for all standard accounts

Everything else is still on quantum-vulnerable signatures, including Bitcoin at 17.0 out of 100 and Ethereum at 40.0. The full ranking shows where each one sits and what it is working on.

Why is quantum proof a spectrum rather than a badge?

Because a chain can be post-quantum in one part of its design and vulnerable in another, and the label hides which. The Hardy Index scores six dimensions separately for exactly this reason.

Some real examples of the distinction. Algorand has signed its State Proofs with Falcon since 2022 while ordinary accounts still use Ed25519. Zcash is a privacy chain whose spend authorisation is elliptic-curve, so private is not the same as quantum-safe. Ethereum runs hash-based validator signatures in devnets while mainnet accounts remain on ECDSA.

Then there is history. IOTA is still widely described as quantum-resistant on the strength of the Winternitz signatures it used at launch. It replaced them with Ed25519 in the Chrysalis upgrade in 2021. It rates in Tier 4 on this index, and that correction is logged in the changelog.

The useful question is therefore never "is this coin quantum proof". It is "what signs a transaction on this chain today, and what happens to the coins already sitting at exposed addresses".

What about coins that market themselves as quantum proof?

A claim is not evidence, and the Hardy Index does not award a rung on the strength of a project's own marketing. Where a deployed scheme cannot be confirmed against a primary source, the chain is held back rather than published with an unverified score.

Three chains sit in that category today. Cellframe lists post-quantum algorithms as available without confirming which scheme secures ordinary transactions by default. QANplatform names a NIST-standardised algorithm and has real component audits, but has no public mainnet to inspect. Quranium describes a live SPHINCS+ mainnet, but its developer documentation was not reachable.

None of that says those projects are wrong. It says the Hardy Index could not check, and publishing an unverified high score would damage this index as much as publishing an unfair low one. The about page lists each case and what would resolve it.

What should you do with this?

Start by checking what you already hold rather than shopping for a replacement. Most readers of this page own something on a chain with a funded migration plan. The useful action is to reduce exposure now, and take that migration when it ships.

The Hardy Index does not tell anyone what to buy, sell or hold. A high score is a statement about cryptography rather than about an asset. How to protect your crypto from quantum computers covers the steps that work wherever you hold. Moving to a quantum-ready chain covers the bigger decision, including when it is the wrong one.

Check any chain on the Index

The Hardy Index rates 23 major chains from 0 to 100 on quantum readiness, as of 12 August 2026, with a primary source behind every figure.

Check any chain on the Index

Questions people also ask

Is there a quantum-proof cryptocurrency?

A small number of chains run post-quantum signatures for every account on mainnet today. As of 12 August 2026, the Hardy Index rates 2 of 23 major chains that way: Quantum Resistant Ledger and Abelian. Even on those chains, quantum proof describes the signature scheme in use rather than a permanent guarantee.

Is Bitcoin quantum proof?

No. Bitcoin uses ECDSA and Schnorr signatures on the secp256k1 curve, both broken by Shor's algorithm on a large enough quantum computer. It scores 17.0 out of 100 on the Hardy Index. Two proposals, BIP-360 and BIP-361, are documented as drafts, and neither is activated and neither introduces a post-quantum signature scheme.

Is XRP or Cardano quantum proof?

Neither is quantum proof today. Both are rated in Tier 3: Committed on the Hardy Index. That means a funded roadmap with public dates and active research, but no post-quantum signature live on mainnet. Their profiles show the roadmap dates and the primary source behind each one.

Are privacy coins quantum proof?

Not automatically, and the two properties are often confused. Zcash spend authorisation uses RedDSA and RedPallas, which are elliptic-curve schemes, and its Halo 2 proof system rests on the same mathematics. Privacy protects who you are from other users. Quantum resistance protects your keys from a future computer.

How can I check a quantum-proof claim myself?

Look for the signature scheme that secures ordinary transactions on mainnet, in the chain's own documentation, rather than in an announcement. If the documentation lists post-quantum algorithms as available without saying they are mandatory, the claim usually describes an option rather than a default. The Hardy Index publishes the primary source it used for every chain it rates.

Where to go next

Sources

  1. The Hardy Score methodology The Hardy Index · primary · checked 12 August 2026
  2. IOTA Ed25519 signature scheme (TIP-9) IOTA Foundation · primary · checked 12 August 2026
  3. Algorand post-quantum technology Algorand Foundation · primary · checked 12 August 2026
  4. Zcash protocol specification Electric Coin Company · primary · checked 12 August 2026

This is a security-readiness assessment, not investment advice.