Chain profile
Mainnet signs with Ed25519, secp256k1, P-256 and BLS, while an ML-DSA-44 account type sits in the live protocol switched off by a feature flag and runs on the experimental Quantumnet test network.
No, not today. Tezos accounts sign with Ed25519 (tz1), ECDSA on secp256k1 (tz2), ECDSA on P-256 (tz3) or BLS on BLS12-381 (tz4), and a sufficiently large quantum computer breaks all four. Tezos is further along than an announcement, though. A post-quantum account type, tz5, using ML-DSA-44 from the final FIPS 204 standard, was merged into Octez by Nomadic Labs and Trilitech engineers and shipped inside Ushuaia, the protocol amendment that activated on mainnet on 30 June 2026. It is switched off there: the protocol constant tz5_account_enable reads false on mainnet, which any reader can check through a public node. In September 2026 the core developers published a plan to make Tezos fully post-quantum through successive protocol amendments and launched Quantumnet, an experimental public test network where tz5 accounts are enabled and consensus attestations use hash-based XMSS signatures. No mainnet date has been published, and turning tz5 on still needs a future amendment that bakers vote to adopt.
Where we are making a judgement call Two judgement calls carry this profile. One is the tier. We read the September 2026 piece by Arthur Breitman, published by Trilitech on behalf of the core developers, together with tz5 code already shipped inside the adopted Ushuaia amendment, as a published plan naming the scheme, which is Tier 3. A reader who treats that piece as a statement of direction, given that Quantumnet is called an experiment and mainnet activation still needs a future baker vote, would place Tezos in Tier 4, with a deployment score of 2 and a Hardy Score of 30.0 instead of 37.5. The other is the signature score of 0, which treats Quantumnet as short of a persistent test network: Tezos Commons calls it an engineering playground not intended for production use, and teztnets.com does not list it. A reader who treats Quantumnet as a persistent public testnet a user can hold keys on would score signature 1, for a Hardy Score of 40.5.
Ed25519 (tz1, the default), ECDSA on secp256k1 (tz2), ECDSA on P-256 (tz3) and BLS on BLS12-381 (tz4), chosen per account; a baker's consensus key may be any of the four
ML-DSA-44 tz5 accounts, in the active protocol but disabled on mainnet by the tz5_account_enable flag, and enabled on the experimental Quantumnet. Quantumnet also uses hash-based XMSS with STARK aggregation for consensus attestations.
FIPS 204 (ML-DSA), finalised August 2024. The XMSS variant used for Quantumnet consensus is not covered by a NIST standard.
Tier 3: Committed. The chain’s own authority, meaning its foundation, its core team or an adopted improvement proposal, has published a plan to replace its fund-protecting signatures with post-quantum ones, naming the scheme or a funded programme to select one, but no post-quantum signature is live on mainnet. A draft proposal is not a plan.
A role not listed is not evidenced either way. Every scheme, and which other chains share it, is in the cryptography registry.
| No. | Dimension | Score | Weight | Contribution |
|---|---|---|---|---|
| 1 | Signature scheme | 0 | 30% | 0.0 |
| 2 | Deployment stage | 5 | 25% | 12.5 |
| 3 | NIST alignment | 8 | 15% | 12.0 |
| 4 | Migration path | 6 | 15% | 9.0 |
| 5 | Exposure | 2 | 10% | 2.0 |
| 6 | Verification | 4 | 5% | 2.0 |
| Hardy Score | 37.5 | |||
Band 0: Classical signatures only on mainnet, with nothing post-quantum protecting live funds. Short-lived devnets and one-off benchmarks sit here: they demonstrate research rather than something a user can hold keys on.
Every account type usable on Tezos mainnet is classical: tz1 Ed25519, tz2 secp256k1, tz3 P-256 and tz4 BLS12-381. The ML-DSA-44 tz5 account type is present in the active protocol, but the constant tz5_account_enable reads false on mainnet, so nothing post-quantum protects XTZ. tz5 accounts are enabled on Quantumnet, but Tezos Commons describes it as an engineering playground not intended for production use, and it is not listed among the Tezos test networks at teztnets.com, so it is not the persistent test network a higher score needs. source
Band 5: Tier 3: Committed.
Tier 3: Committed. Tezos core developers, in a piece by co-founder Arthur Breitman published by Trilitech, set out a plan for Tezos to become fully post-quantum through protocol amendments, naming ML-DSA-44 for tz5 accounts, and the tz5 code already sits in the adopted Ushuaia amendment. Nothing post-quantum is live on mainnet. source
Band 6 to 8: The scheme is NIST-selected but the standard is not yet final, or a NIST-approved scheme is named but not yet deployed.
The account scheme implemented and tested is ML-DSA-44, a parameter set of ML-DSA under the final FIPS 204 standard, carried in Octez as a new tz5 address type rather than named as a candidate. It is built into the active protocol but disabled on mainnet, so it is a NIST-approved scheme named and not yet deployed. source
Placement in the band The top of the band rather than a 9: ML-DSA-44 is under a final standard and is already in the active protocol, but tz5_account_enable is false on mainnet, so the scheme is not in use, and the consensus side of the plan uses a LeanEthereum variant of XMSS with STARK aggregation that no NIST standard covers.
Band 6 to 8: A credible published plan exists with a mechanism identified, but key parts are unbuilt or undated.
The route off a vulnerable key is built: a holder would move funds to a tz5 account once an amendment enables it, and Tezos has adopted every protocol change since 2019 by on-chain self-amendment, so governance can plausibly deliver it. The published plan also sketches a fencepost date after which a post-quantum zero-knowledge proof of the seed words may be required. source
Placement in the band A 6 rather than a 7 or 8: tz5 is a new address, so migration means a transfer rather than keeping an address, the fencepost and seed-proof idea is stated as something the protocol may do rather than designed, and nothing is dated.
Band 0 to 2: Public keys are exposed for effectively all accounts, or a large, measured share of total supply sits in exposed addresses.
Tezos addresses are hashes of public keys, and an account stays unrevealed until it transacts. Once it sends a transaction or a reveal operation its classical key is on-chain, and bakers' consensus keys are public by design, so effectively all active XTZ sits behind an exposed key. source
Placement in the band At the top of the band rather than a 0 or a 1: the hashed address keeps the key of a never-used account private, a structural protection the floor of this band lacks, though almost no active supply benefits from it.
Band 3 to 5: A post-quantum component exists, on mainnet, on a persistent testnet or as a merged implementation, but is unreviewed.
The tz5 component is open source and merged into Octez, built on bindings to the libcrux ML-DSA library, and it runs on Quantumnet. Its merge requests, 20236, 20257 and 20680, were approved by engineers who are themselves among the feature's authors, Albin Coquereau, Victor Dumitrescu and Marina Polubelova, and by their colleagues, so the review is from inside the authoring team, and no audit of the component has been published. source
Placement in the band A 4 rather than a 3 or a 5: the code is merged and ships, switched off, inside the protocol mainnet runs, which is more than a branch, but the network where it is switched on is an engineering playground rather than a persistent test network. Review of the upstream libcrux library does not count here.
The deployment dimension is not a separate judgement. It is Tier 3 expressed as a number. See the tier mapping.
The 9 chains Tezos sits among, out of 80 rated. The last column is the gap in Hardy points from Tezos.
| Rank | Chain | Tier | Hardy | vs XTZ |
|---|---|---|---|---|
| 17 | Aptos | 3: Committed | 39.0 | +1.5 |
| 18 | Stellar | 3: Committed | 39.0 | +1.5 |
| 19 | Ethereum | 3: Committed | 38.5 | +1.0 |
| 20 | Zcash | 3: Committed | 38.0 | +0.5 |
| 21 | Tezos this chain | 3: Committed | 37.5 | |
| 22 | Polkadot | 3: Committed | 36.5 | -1.0 |
| 23 | Tron | 4: Debating | 34.5 | -3.0 |
| 24 | Cardano | 3: Committed | 34.0 | -3.5 |
| 25 | Sei | 4: Debating | 24.5 | -13.0 |
ML-DSA-44 support is merged into Octez: bindings to the libcrux ML-DSA library, ML-DSA keys and signatures in the crypto library, and the tz5_account_enable feature flag in the protocol, all by Nomadic Labs and Trilitech engineers. source
Ushuaia, adopted by baker vote, activates on mainnet carrying tz5 ML-DSA-44 accounts behind a feature flag intended for test networks. The flag reads false on mainnet. source
Tezos core developers publish their post-quantum plan: the pieces for a fully post-quantum Tezos will be submitted over time as protocol amendments, with moving users to post-quantum keys named as the priority. source
Quantumnet launches as an experimental public test network with tz5 accounts enabled, XMSS attestations with STARK aggregation, a round-robin baker selection replacing the VDF, and ZODA in the data availability layer. source
Enabling tz5 accounts on mainnet, which needs a protocol amendment adopted by baker vote. No such proposal was in the voting period that opened on 21 October 2026, and no date has been published. source
Proposed: recover with a post-quantum proof
The core developers' plan says that if users have not moved to a post-quantum key by a fencepost date, the protocol may still require a post-quantum zero-knowledge proof of knowledge of the seed words. It is stated as a possibility, not a design.
As of 22 October 2026. source Published beside the score, not in it. Every chain's stance is compared on the commitments page.
Exposure measures how much of the chain's value already sits behind a public key that an attacker can record today and break later. This is the part of the threat that a future upgrade cannot undo.
Tezos derives an address from a hash of the public key, so an account that has been funded but has never acted has not published its key. An account is unrevealed until it transacts, and the reveal puts its classical public key on-chain, where it stays. Bakers sign blocks and attestations continuously, so their keys are public by design, and ordinary holders who delegate or transact have revealed theirs. In practice effectively all economically active XTZ sits behind a key that can be recorded today against a future quantum computer. The tz5 account type does not change this for existing balances: it is a new address, so protection comes from moving funds to it once it is enabled.
What this rating means for you
Tezos has a funded roadmap but no post-quantum signature protecting funds on mainnet yet. Until it ships, your exposure is the ordinary one, and the steps that reduce it cost nothing.
Editorial guidance from the Hardy Index.
We will email you the day this rating moves, with the changelog note that explains why. Nothing else, and nothing in between.
Not today. Every account type usable on mainnet, tz1, tz2, tz3 and tz4, rests on elliptic-curve or pairing cryptography that a sufficiently large quantum computer would break. A post-quantum tz5 account type exists in the protocol but is switched off on mainnet.
A Tezos account type that signs with ML-DSA-44, a parameter set of the ML-DSA standard NIST finalised as FIPS 204. It was merged into Octez in early 2026 and shipped inside the Ushuaia protocol behind the feature flag tz5_account_enable, which reads false on mainnet and is enabled on the experimental Quantumnet test network.
Read the protocol constants from any public Tezos node, for example through the TzKT RPC at /chains/main/blocks/head/context/constants. The constant tz5_account_enable reads false on mainnet as of 22 October 2026. A change would arrive with a protocol amendment, which is public and voted on before it activates.
An experimental public test network launched in September 2026 by engineers at Nomadic Labs, Trilitech and other contributors. It enables tz5 accounts and replaces other quantum-vulnerable parts of Tezos, including BLS attestations, which become hash-based XMSS signatures with STARK aggregation. It is not intended for production use.
On the current design, yes. A tz5 account is a new address, so a holder protects funds by transferring them to one once an amendment enables it. The core developers have said further experiments will look at adding a post-quantum key to an existing account, and that after a fencepost date the protocol may require a zero-knowledge proof of the seed words.
A rating is only true as of the day an editor last reviewed it, so both forms below carry that date and the methodology version, with the date its cited sources were last checked. If you are quoting the score, quote those too.
The Hardy Index (2026). Tezos: quantum readiness assessment. Hardy Score 37.5 of 100, Tier 3: Committed. Methodology v1.8. Last reviewed 22 October 2026; sources checked 13 November 2026. https://hardyindex.com/chains/tezos
@misc{hardyindex_tezos_2026,
author = {{The Hardy Index}},
title = {Tezos: quantum readiness assessment},
year = {2026},
howpublished = {\url{https://hardyindex.com/chains/tezos}},
note = {Hardy Score 37.5 of 100, Tier 3: Committed. Methodology v1.8},
urldate = {2026-11-13}
} The whole dataset is reusable under the terms on the about page. A machine-readable version of this page is at /chains/tezos.md.
This is a security-readiness assessment, not investment advice.