Chain profile
Mainnet signs with ECDSA on secp256k1, and Sei Labs has filed SIP-5, a Draft proposal to bind ML-DSA-44 keys to existing accounts and then end classical signing at a governance-set height.
No. Sei accounts are secured by ECDSA on the secp256k1 curve, the same key behind both an account's 0x and sei1 addresses, and validators sign consensus with Ed25519. A sufficiently large quantum computer would break both. Sei Labs has put a detailed answer on the table. SIP-5, Post-Quantum Authorization for EVM Accounts, was opened in Sei's own improvement-proposal repository on 27 July 2026 with status Draft. It lets an existing account bind an ML-DSA-44 key, from the finalised FIPS 204 standard, without changing its address or balance, and then sets out a governance-chosen cutoff height after which accounts that have not bound a post-quantum key can still receive funds but can no longer send. Sei Labs' own announcement says it is not proposing SIP-5 for immediate implementation and that a cutoff would follow if and when the plan is adopted. No code, testnet or date exists, which is why Sei sits in Tier 4 rather than Tier 3.
Where we are making a judgement call The tier is a judgement call. Sei Labs is Sei's core team, and two of its publications name ML-DSA: Draft SIP-5, and the Sei Giga whitepaper, which says Giga intends to use ML-DSA in the short term. A reader who takes the whitepaper as a core-team plan naming a scheme would place Sei in Tier 3, which raises the deployment score from 2 to 5 and the Hardy Score from 24.5 to 32.0. We read both as the same proposal, because the whitepaper describes the SIP-5 design and Sei Labs' own announcement calls it a proposal it is not putting forward for immediate implementation. A second, smaller call: SIP-5 is scored as proposed, and nothing in it binds Sei's validators, whose Ed25519 consensus keys it does not address.
ECDSA on secp256k1 for accounts (0x and sei1 addresses from the same key); Ed25519 for validator consensus
ML-DSA-44 specified for EVM accounts in Draft SIP-5, bound to existing addresses, with a governance-set cutoff for classical signing. Not implemented or deployed.
FIPS 204 (ML-DSA), finalised August 2024
Tier 4: Debating. Post-quantum work on the chain’s own signatures is documented by people with authority over it, in a formal improvement proposal or a public research programme, but no scheme is agreed and no timeline is published.
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 | 2 | 25% | 5.0 |
| 3 | NIST alignment | 6 | 15% | 9.0 |
| 4 | Migration path | 5 | 15% | 7.5 |
| 5 | Exposure | 2 | 10% | 2.0 |
| 6 | Verification | 2 | 5% | 1.0 |
| Hardy Score | 24.5 | |||
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.
Sei signs with ECDSA on secp256k1, with 0x and sei1 addresses both derived from the same public key, and nothing post-quantum protects SEI or any token on mainnet. SIP-5 is a document: no implementation of it runs on mainnet or on any public test network. source
Band 2: Tier 4: Debating.
Tier 4: Debating. SIP-5 is a formal proposal in Sei's own improvement process, written by Sei Labs authors, with Philip Su of Sei Labs named as its reviewer, and announced on the Sei blog. It is not Tier 3 because SIP-5 is a Draft, and Sei Labs says in the announcement that it is not proposing the change for immediate implementation and that a cutoff would be set if and when the plan is adopted. A draft proposal is not a plan. 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.
SIP-5 names a single parameter set, ML-DSA-44 from the final FIPS 204, and fixes its key and signature encodings, the pure signing mode and a domain-separation context. The Sei Giga whitepaper, by Sei Labs authors, separately states that Giga intends to use ML-DSA in the short term. source
Placement in the band A 6 rather than a 7: ML-DSA-44 is named but not deployed anywhere, and Sei Labs describes it as an emergency path while it researches a faster scheme whose standard is unknown. Not a 5, because this is a specified parameter set of a final standard, not a candidate reference.
Band 3 to 5: Migration is acknowledged as a problem with no agreed mechanism, or the mechanism is contested.
SIP-5 sets out a complete mechanism: an existing account binds a post-quantum key at its current address, a third party can pay for the binding, an account can switch itself to post-quantum-only signing ahead of the network, and a governance-set cutoff height then stops classical signing for everyone, with a minimum notice period enforced in consensus. source
Placement in the band The top of the 3 to 5 band rather than a 6: the mechanism covers accounts whose keys are already public and enforces a notice period in consensus, which lifts it above a bare acknowledgement, but SIP-5 is a Draft that Sei Labs itself is not proposing for immediate implementation, with no implementation, no registration height and no notice-period value, and a draft proposal is not a plan.
Band 0 to 2: Public keys are exposed for effectively all accounts, or a large, measured share of total supply sits in exposed addresses.
Both Sei address formats are hashes of the public key, so an account that has never signed keeps its key private. The key is recorded on-chain once an account sends a transaction or associates its two addresses, and accounts holding meaningful value have almost all done one or the other. source
Placement in the band At the top of the band rather than a 0 or a 1: the hashed address genuinely protects accounts that have never signed or associated, though on a chain built for high-frequency trading that covers little of the value.
Band 0 to 2: No post-quantum component exists, or the claims rest on marketing.
No post-quantum component exists to verify. SIP-5 is an unmerged design with no reference implementation, and its discussion thread on GitHub has no replies, so it has had no outside review either. Under v1.8 a proposal is not a component. source
Placement in the band The top of the band rather than a 0 or a 1: there is nothing to verify, but Sei is not marketed as quantum-safe. Its announcement calls SIP-5 a proposal, so its position does not rest on marketing.
The deployment dimension is not a separate judgement. It is Tier 4 expressed as a number. See the tier mapping.
The 9 chains Sei sits among, out of 80 rated. The last column is the gap in Hardy points from Sei.
| Rank | Chain | Tier | Hardy | vs SEI |
|---|---|---|---|---|
| 21 | Tezos | 3: Committed | 37.5 | +13.0 |
| 22 | Polkadot | 3: Committed | 36.5 | +12.0 |
| 23 | Tron | 4: Debating | 34.5 | +10.0 |
| 24 | Cardano | 3: Committed | 34.0 | +9.5 |
| 25 | Sei this chain | 4: Debating | 24.5 | |
| 26 | Cosmos Hub | 4: Debating | 23.5 | -1.0 |
| 27 | Kaspa | 4: Debating | 20.5 | -4.0 |
| 28 | BNB Chain | 4: Debating | 20.0 | -4.5 |
| 29 | Monad | 4: Debating | 20.0 | -4.5 |
Version 3 of the Sei Giga whitepaper, by Sei Labs authors, adds a post-quantum section: bind a post-quantum key to each existing account before a governance-set cutoff, with ML-DSA as the short-term scheme, described as a temporary path not fast enough for Giga's throughput. source
SIP-5, Post-Quantum Authorization for EVM Accounts, is opened in Sei's improvement-proposal repository with status Draft. It specifies ML-DSA-44 key binding, new transaction types, sponsored registration and a governance-set cutoff for classical signatures. source
Sei Labs announces SIP-5 as a proposal for the ecosystem to decide on, not for immediate implementation, and says it is beginning work on new, high-performance post-quantum cryptography. source
Implementation of SIP-5, a registration height on mainnet, and any classical-signature cutoff. SIP-5 leaves every activation height and the notice period to be fixed before it can become Final. source
Proposed: sunset legacy signatures
Draft SIP-5 proposes a governance-set cutoff height after which accounts with no post-quantum key can still receive funds and be called, but can no longer originate transactions. It provides no recovery path and leaves any recovery to a separate SIP.
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.
Sei derives two addresses from one secp256k1 key: a 0x address from the Keccak hash of the uncompressed key, as on Ethereum, and a sei1 address from a SHA-256 and RIPEMD-160 hash of the compressed key. Neither reveals the key until the account signs. The chain records the public key as soon as an account sends a transaction or links its two addresses, and linking is needed for many cross-format token transfers, so an account in active use has almost always published its key. SIP-5 would keep the 20-byte address format, so the exposure question it answers is not which keys are public but whether a public key can still authorise a spend after the cutoff.
What this rating means for you
Sei has acknowledged the threat without agreeing a plan, so nothing is going to change for holders in the near term. That makes address hygiene the part worth attending to.
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.
No. Sei accounts sign with ECDSA on the secp256k1 curve and validators sign consensus with Ed25519, and a sufficiently large quantum computer would break both. Sei Labs has filed a Draft proposal, SIP-5, for post-quantum account keys, but nothing post-quantum protects SEI on mainnet or on a test network.
SIP-5, Post-Quantum Authorization for EVM Accounts, is a Draft proposal opened on 27 July 2026 in Sei's improvement-proposal repository. It lets an existing account bind an ML-DSA-44 key while keeping its address and balance, adds transaction types that sign with that key, and proposes a governance-set height after which classical signatures stop authorising transactions. It carries no dates and no implementation.
Under the draft, after the cutoff they would keep their balances and could still receive funds, but could not send. SIP-5 offers no recovery path for them and says one would need a separate proposal. The cutoff height itself would be set by governance, with a minimum notice period enforced by the chain.
Both come from the same secp256k1 key, so they share one exposure. SIP-5 covers EVM accounts, and SIP-3, which is moving Sei to EVM-only transactions, would leave the 0x path as the way a holder initiates a transaction, so a binding on the EVM account is the one that would matter.
Because Tier 3 needs a plan the chain's authority has adopted or published as a plan, and Sei Labs presents SIP-5 as a proposal for the ecosystem to decide on, not as something to implement now. The profile flags this as a judgement call, since Sei Labs is the core team and its whitepaper also names ML-DSA.
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). Sei: quantum readiness assessment. Hardy Score 24.5 of 100, Tier 4: Debating. Methodology v1.8. Last reviewed 22 October 2026; sources checked 13 November 2026. https://hardyindex.com/chains/sei
@misc{hardyindex_sei_2026,
author = {{The Hardy Index}},
title = {Sei: quantum readiness assessment},
year = {2026},
howpublished = {\url{https://hardyindex.com/chains/sei}},
note = {Hardy Score 24.5 of 100, Tier 4: Debating. 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/sei.md.
This is a security-readiness assessment, not investment advice.