Sei has put forward a proposal that would allow every account on its blockchain to adopt quantum-resistant cryptography while keeping existing addresses and balances intact. The draft measure, called SIP-5, lets users attach quantum-safe keys to their current accounts at their own pace, without forced migration or address changes.
The quantum threat to blockchains remains theoretical but has begun to structure protocol roadmaps. A sufficiently large quantum computer could theoretically break the elliptic-curve cryptography that secures most blockchain addresses today. Sei's approach differs from full address migration: rather than requiring users to move funds to new quantum-resistant addresses, SIP-5 appends quantum-safe key material to existing accounts, preserving transaction history and on-chain identity.
Sei laid out the proposal in a draft on GitHub. The mechanics allow users to register quantum-resistant public keys alongside their current cryptographic material. Once registered, an account can be signed with either the original key or the quantum-safe key, giving users optionality on adoption timing. The proposal does not define a mandatory migration deadline or specify which quantum-resistant algorithm Sei will standardize, leaving those decisions to governance and future implementation phases.
Other blockchains have taken different approaches. Ethereum has long acknowledged the quantum risk but has not prioritized protocol-level quantum migration in its roadmap. Bitcoin developers have discussed address format upgrades that could accommodate post-quantum signatures, though no formal proposal has advanced. Cosmos-based chains, which share some infrastructure with Sei, have begun preliminary work on quantum-resistant key types in their SDK.
Sei's move comes as the broader crypto industry watches quantum computing development. Last year, Google announced a quantum chip it said achieved "quantum advantage" on certain computational problems, though not on the elliptic-curve discrete-log problem that secures blockchain keys. The timeline for a cryptographically relevant quantum computer remains uncertain, with most estimates placing it 10 to 15 years away.
SIP-5 is currently a draft proposal in Sei's governance process and does not represent a live network change. Adoption would depend on community vote, then gradual user implementation. The proposal's lack of a mandatory timeline or migration deadline means quantum-safe key adoption on Sei could remain partial for years, with some accounts retaining only classical keys.
The measure is one of the first concrete post-quantum migration paths any major blockchain has published for user-facing implementation. If approved and adopted, it establishes a model where quantum safety becomes an account-level choice rather than a network-wide fork, preserving the addresses and balances of users who do not upgrade.
