Stellar Unveils Three-Stage Plan for Quantum-Safe Cryptography Migration

In brief

Stellar developers have unveiled a three-stage migration plan to quantum-safe cryptography ahead of the looming "Q-Day" threat.

Enterprise wallets can begin migrating in 2026, with all accounts able to upgrade by end of 2027 without changing their addresses.

The biggest open question is what to do with dormant accounts whose holders can no longer be reached.

The Stellar Development Foundation on Tuesday unveiled a sweeping three-stage roadmap to protect its blockchain network from the coming threat of quantum computing. The move underscores growing alarm about a technological shift that experts warn could eventually unravel the cryptographic foundations securing trillions of dollars in digital assets.

Stellar faces two distinct threats: attackers forging validator signatures to compromise the network's consensus mechanism, and the ability to derive private keys from public ones, enabling account takeover. The latter is the harder problem and the primary focus of the Quantum Preparedness Plan.

Stellar holds a structural advantage over blockchains like Bitcoin and Ethereum, the foundation said: its account identity is separated from its signing keys, meaning users can swap in quantum-safe cryptography without changing their address or migrating their balance. This makes the transition significantly less disruptive.

The proposed roadmap would unfold in three stages. In 2026, post-quantum signature verification will be added to Stellar's smart contract layer, allowing enterprise wallets to begin migrating immediately. In 2027, a protocol-level upgrade will enable every Stellar account to add a quantum-safe signer while keeping the same address. The third stage—fully deprecating the current cryptography—will be timed based on quantum computing progress and community readiness.

One unresolved challenge involves dormant accounts whose holders are unreachable. Any hard cutoff would effectively freeze those accounts, and the Foundation says that decision will require open community discussion rather than a top-down resolution.

Experts say that quantum computers will eventually break the elliptic curve cryptography that secures most major blockchain networks, including Bitcoin, Ethereum, and Stellar. While the quantum threat will impact many kinds of cryptography, such networks face a particularly acute vulnerability because their ledgers are public and permanent—meaning encrypted data harvested today could be decrypted the moment quantum hardware becomes powerful enough.

When a powerful enough quantum computer will come online is still a moving target, but the estimates are getting tighter. The National Institute of Standards and Technology, which had previously placed the danger zone at 2030 and beyond, has updated its guidance to 2029. Google has set 2029 as its internal deadline for post-quantum readiness, while crypto researchers recently proposed a “Q-Day” target as early as 2030.

Bitcoin developers are considering multiple proposals—both official and otherwise—to mitigate the threat to the leading crypto network, while Ethereum developers have formed a post-quantum team to devise a path forward for that network. Stellar’s plan is the latest in a broader industry push to reckon with a seemingly inevitable post-quantum world.