The proposal does not force an immediate change. Users can migrate at their own pace, keeping the same wallet address, token balances, and smart contract approvals throughout. Sei Labs framed the effort as deliberate early preparation, noting in the SIP-5 text that the goal is to act well before any real threat exists. The proposal is open for ecosystem deliberation and has not yet been ratified or scheduled for implementation.

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Why Quantum Computing Is a Problem for Every EVM Chain

Every wallet on Ethereum, Sei, and compatible blockchains currently relies on ECDSA (Elliptic Curve Digital Signature Algorithm), a mathematical system that is effectively unbreakable for today's computers. A sufficiently powerful quantum computer running Shor's algorithm could reverse that math in minutes, recovering a private key from a publicly exposed public key and enabling theft or forgery.

In March 2026, Google Quantum AI published updated calculations suggesting the attack would require roughly 500,000 physical qubits, a figure about 20 times lower than previous estimates. The paper also estimated the operation would require approximately 1,200 to 1,450 logical qubits and could complete in as little as 9 to 23 minutes. That lower bound falls within the time needed to confirm a single Bitcoin block. The paper's conclusion was direct: "the safest course of action for the cryptocurrency community is to begin preparing itself against quantum attacks immediately."

Current quantum hardware sits in the hundreds to low-thousands of qubits range, orders of magnitude below the attack threshold, but the engineering consensus puts the realistic risk window in the early-to-mid 2030s.

Responding to that timeline, the U.S. National Institute of Standards and Technology finalized three post-quantum cryptographic standards in August 2024. NIST's guidance designates ML-DSA (formerly known as CRYSTALS-Dilithium) as the default choice for post-quantum digital signatures. Two companion standards cover key encapsulation (ML-KEM/FIPS 203) and hash-based signatures (SLH-DSA/FIPS 205). NIST also sets a formal deprecation schedule: ECDSA deprecated by 2030 and disallowed entirely by 2035.

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The Performance Trade-Off Sei Cannot Ignore

Switching signature schemes is not a straightforward substitution. An ECDSA signature is roughly 72 bytes. The minimum-security version of ML-DSA produces signatures of approximately 2,420 bytes. SLH-DSA (formerly SPHINCS+), a hash-based algorithm with stronger long-term security assumptions, can reach nearly 50,000 bytes per signature.

A naive swap would increase transaction sizes by roughly 20 times, compressing block capacity and driving up fees.

Sei Labs acknowledged this directly in SIP-5, noting the network is simultaneously researching higher-performance post-quantum alternatives. The tension is acute for Sei specifically because the network's Giga upgrade targets 200,000 transactions per second and sub-400 millisecond finality. Adding kilobytes to every transaction cuts directly against that goal.

Ethereum faces the same problem. The Ethereum Foundation formed a dedicated post-quantum security team in January 2026 and launched pq.ethereum.org as a coordination hub in March 2026. More than 10 client teams are running weekly post-quantum interoperability devnets. The Ethereum roadmap targets full post-quantum infrastructure by 2029, anchored by EIP-8141, a native account abstraction proposal that enables signature-scheme agility, expected in the Hegotá hard fork later this year. That roadmap also incorporates leanXMSS, a hash-based signature scheme for consensus, and STARK-based commitments replacing KZG.

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What This Means for South Asian and African Users

The fee and wallet-update questions carry the most weight for users in South Asia and Africa, where crypto adoption is structurally mobile-first and transaction sizes directly determine accessibility.

India ranked first across all sub-indices in the 2025 Chainalysis Global Crypto Adoption Index, with most on-chain activity originating from smartphones, particularly mid-range Android devices. Across Sub-Saharan Africa, mobile money platforms like M-Pesa and MTN Mobile Money have served as the primary on-ramp to crypto adoption.

For users in those markets transacting in small amounts, a significant gas fee increase from larger post-quantum signatures is not a marginal concern. It directly undercuts the value proposition of decentralized finance for users making low-value transactions.

A threat known as "Store Now, Decrypt Later" (SNDL) makes the case for early migration more urgent than the current state of quantum hardware might suggest. Adversaries may already be harvesting public blockchain data with the intention of decrypting it once quantum hardware matures. High-value remittance corridors, including the India-Gulf flow and African diaspora transfers, are particularly attractive targets because the transaction records are public and permanent. A wallet address that is active and valuable today will still be on-chain when quantum decryption becomes viable. Migrating to a quantum-resistant key before any enforcement deadline seals that address against future retroactive attack.

SIP-5 also depends on wallets, block explorers, and developer tooling catching up before any enforcement cutoff takes effect. Third-party non-custodial wallets common in emerging markets often update more slowly than flagship apps. A user who does not update, or does not understand the migration requirement, risks losing the ability to send transactions without warning. No regulatory body in India, Nigeria, or most of Sub-Saharan Africa currently oversees crypto wallet providers or could compel them to inform users of the change. The burden of communication falls entirely on exchanges, DApp developers, and community educators.

EVM developers building in India, Nigeria, and East Africa also face a near-term review task. Smart contract integrations that reference user keys directly, or that handle token approvals, will need to be audited and updated once PQC key registration becomes active on the network. Developers who build that review into their roadmaps now will avoid a harder forced migration later.

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Sei's Current Network Context

Sei's on-chain metrics provide honest backdrop for evaluating this proposal. Total value locked on the network fell from roughly $626 million in July 2025 to approximately $41.6 million by April 2026, according to DefiLlama data. Daily active addresses dropped from near 2 million in March 2026 to fewer than 5,000 by late June. The SEI token trades in a range of approximately $0.0453 to $0.077 as of mid-2026, with a market cap of approximately $478 million as of May 2026 per CoinMarketCap; this figure should be verified against live CoinGecko data before publication.

Roughly one-third of the token supply remains locked, with monthly unlocks of 112 to 132 million tokens continuing through mid-2027.

SIP-5 follows SIP-3 and SIP-4 in Sei's governance series. SIP-3 completed Sei's transition to a fully EVM-only chain by deprecating its original CosmWasm and Cosmos transaction types. The quantum-resistance proposal represents a longer-horizon planning layer on top of that infrastructure work.

If ratified, SIP-5 would establish a formal, on-chain quantum migration path for Sei users, positioning the network to meet future cryptographic standards ahead of the NIST 2035 enforcement deadline.