--- title: Is Sei quantum-safe? chain: Sei ticker: SEI hardy_score: 24.5 rank: 25 of 80 tier: "4: Debating" url: "https://hardyindex.com/chains/sei" updated: 2026-10-22 reviewed: 2026-11-13 methodology_version: 1.8 --- # Is Sei quantum-safe? **Hardy Score 24.5 / 100. Rank 25 of 80. Tier 4: Debating. Last editorial review 22 October 2026; sources checked 13 November 2026.** 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. > This is a security-readiness assessment, not investment advice. ## Summary 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. ## 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. ## Score breakdown | # | Dimension | Score | Weight | Contribution | |---:|---|---:|---:|---:| | 1 | Signature scheme | 0/10 | 30% | 0.0 | | 2 | Deployment stage | 2/10 | 25% | 5.0 | | 3 | NIST alignment | 6/10 | 15% | 9.0 | | 4 | Migration path | 5/10 | 15% | 7.5 | | 5 | Exposure | 2/10 | 10% | 2.0 | | 6 | Verification | 2/10 | 5% | 1.0 | | | **Hardy Score** | | | **24.5** | ### 1. Signature scheme: 0/10 Anchor 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: https://docs.sei.io/learn/accounts ### 2. Deployment stage: 2/10 Anchor 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: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md ### 3. NIST alignment: 6/10 Anchor 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. 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. Source: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md ### 4. Migration path: 5/10 Anchor 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. 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. Source: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md ### 5. Exposure: 2/10 Anchor 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. 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. Source: https://docs.sei.io/learn/accounts ### 6. Verification: 2/10 Anchor 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. 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. Source: https://github.com/sei-protocol/sips/discussions/15 ## Nearest chains in the ranking The 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](https://hardyindex.com/chains/tezos) | 3: Committed | 37.5 | +13.0 | | 22 | [Polkadot](https://hardyindex.com/chains/polkadot) | 3: Committed | 36.5 | +12.0 | | 23 | [Tron](https://hardyindex.com/chains/tron) | 4: Debating | 34.5 | +10.0 | | 24 | [Cardano](https://hardyindex.com/chains/cardano) | 3: Committed | 34.0 | +9.5 | | 25 | **Sei** | 4: Debating | 24.5 | this chain | | 26 | [Cosmos Hub](https://hardyindex.com/chains/cosmos-hub) | 4: Debating | 23.5 | -1.0 | | 27 | [Kaspa](https://hardyindex.com/chains/kaspa) | 4: Debating | 20.5 | -4.0 | | 28 | [BNB Chain](https://hardyindex.com/chains/bnb-chain) | 4: Debating | 20.0 | -4.5 | | 29 | [Monad](https://hardyindex.com/chains/monad) | 4: Debating | 20.0 | -4.5 | ## Signature scheme - **On mainnet today:** ECDSA on secp256k1 for accounts (0x and sei1 addresses from the same key); Ed25519 for validator consensus - **Post-quantum scheme:** 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. - **NIST standard:** FIPS 204 (ML-DSA), finalised August 2024 - **Readiness tier:** 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. ## Cryptography in use - **Account signatures:** [ECDSA on secp256k1](https://hardyindex.com/algorithms/ecdsa-secp256k1.md). Mainnet, default. One key derives both the 0x and the sei1 address. Source (specification or proposal): https://docs.sei.io/learn/accounts - **Validator consensus:** [Ed25519](https://hardyindex.com/algorithms/ed25519.md). Mainnet, mandatory. All 40 active validators' consensus keys read tendermint/PubKeyEd25519 on mainnet. Source (read on-chain): https://rpc.sei-apis.com/validators?per_page=100 - **Account signatures:** [ML-DSA](https://hardyindex.com/algorithms/ml-dsa.md) (ML-DSA-44). Specified, not deployed. Specified in Draft SIP-5; no implementation exists. Source (specification or proposal): https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md A role not listed here is not evidenced either way. See https://hardyindex.com/algorithms.md. ## Roadmap - **29 June 2026** (shipped): 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: https://arxiv.org/html/2505.14914v3 - **27 July 2026** (shipped): 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: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md - **28 July 2026** (in-progress): 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: https://blog.sei.io/keeping-the-sei-network-safe-from-quantum-computers/ - **No date published** (proposed): 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: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md ## If holders never migrate **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: https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md ## Exposure 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. ## Frequently asked questions ### Is Sei quantum-safe? 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. ### Is Sei quantum-safe? 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. ### What is SIP-5? 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. ### What would happen to Sei accounts that never add a post-quantum key? 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. ### Do Sei's 0x and sei1 addresses need separate migrations? 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. ### Why is Sei in Tier 4 if Sei Labs wrote the proposal? 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. ## What this rating means if you hold Sei Plain-language guidance from the same publication, with no product recommendation attached. - [Is my crypto safe from quantum computers?](https://hardyindex.com/guides/is-my-crypto-safe-from-quantum-computers.md) - [How to protect your crypto from quantum computers](https://hardyindex.com/guides/how-to-protect-crypto-from-quantum-computers.md) - [All guides](https://hardyindex.com/guides.md) ## Sources 1. [SIP-5: Post-Quantum Authorization for EVM Accounts](https://github.com/sei-protocol/sips/blob/main/sips/sip-5.md): Sei Protocol (GitHub) (primary, checked 22 October 2026) 2. [SIP-5 discussion](https://github.com/sei-protocol/sips/discussions/15): Sei Protocol (GitHub) (primary, checked 22 October 2026) 3. [SIP-1: SIP purpose and guidelines](https://github.com/sei-protocol/sips/blob/main/sips/sip-1.md): Sei Protocol (GitHub) (primary, checked 22 October 2026) 4. [Keeping the Sei Network safe from quantum computers](https://blog.sei.io/keeping-the-sei-network-safe-from-quantum-computers/): Sei Blog (primary, checked 22 October 2026) 5. [Sei Giga (whitepaper, version 3)](https://arxiv.org/html/2505.14914v3): Sei Labs (arXiv) (primary, checked 22 October 2026) 6. [Accounts](https://docs.sei.io/learn/accounts): Sei documentation (primary, checked 22 October 2026) 7. [SIP-3: Deprecating CosmWasm and Cosmos](https://github.com/sei-protocol/sips/blob/main/sips/sip-3.md): Sei Protocol (GitHub) (primary, checked 22 October 2026) 8. [Sei mainnet validator set](https://rpc.sei-apis.com/validators?per_page=100): Sei mainnet RPC (primary, checked 22 October 2026) 9. [FIPS 204: Module-Lattice-Based Digital Signature Standard (ML-DSA)](https://csrc.nist.gov/pubs/fips/204/final): NIST (primary, checked 22 October 2026) ## How to cite this rating A rating is only true as of the day it was reviewed, so both forms carry the review date and the methodology version. 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 ```bibtex @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} } ``` --- Methodology: https://hardyindex.com/methodology (v1.8). Cite as: The Hardy Index, "Sei", https://hardyindex.com/chains/sei, as of 13 November 2026.