Ethereum Foundation Targets Quantum-Resistant L1 Overhaul by December 2029

Quantum-Proof by December 2029

The risk that a large-scale quantum computer could one day forge the elliptic curve signatures protecting every Ethereum (ETH) account has moved from theory to roadmap: the Ethereum Foundation aims to convert the network's execution, consensus and data layers to post-quantum cryptography by December 2029. The target sits inside Lean Ethereum, a long-term effort to simplify the base protocol while strengthening security and scalability together. Discussion of the plan lands while the Ethereum (ETH) price debate dominates short-term attention, but the Foundation's stated work is cryptographic rather than market-facing. Post-quantum here means schemes that withstand attacks from both classical and quantum machines, with hash-based signatures the approach NIST has standardized first. Ethereum's core decision is a bet on that approach. In August, the Foundation moved away from Poseidon, a hash function it had studied for eight years as a core layer-1 primitive, in favor of the long-established SHA and BLAKE families. The reversal followed advances in SNARK proving, which now let standard hash functions run efficiently inside zero-knowledge proofs where bespoke designs were once the only workable option. On that foundation, the network plans hash-based post-quantum signing, a compression technique that folds many signatures into one compact proof, and the replacement of BLS, the scheme that currently binds the validator set together. The stakes are structural: staking deposits, withdrawal credentials and every historical address rest on signatures a quantum machine could reproduce, which is why the Foundation treats the work as a full L1 rebuild rather than an incremental patch. Researchers have also sketched an emergency-recovery hard fork as a contingency should a quantum attack arrive sooner than expected. The Foundation frames December 2029 as an objective; no upgrade has been scheduled against it, and the target places the redesign at the center of the broader Ethereum roadmap.

Rivals Move Faster, Experts Split

Sui holds the most concrete execution milestone among altcoin networks. Mysten Labs reported on October 13 that it processed the first native Devnet transaction signed with ML-DSA-65, an algorithm the US National Institute of Standards and Technology (NIST) has standardized, and it targets mainnet adoption for standard accounts in the first quarter of 2027, pending external security audits. The project pairs that scheme with hash-based SLH-DSA for smart-contract vaults holding high-value assets, and built a migration path that reuses existing recovery phrases. Stellar is close behind on protocol plumbing: the Stellar Development Foundation embedded NIST-standard ML-DSA verification in core software version 30, published October 16, so the Soroban platform can verify quantum-resistant signatures, and the Bell upgrade faces a testnet rollout on November 3 before a mainnet validator vote on November 23. Approval would not flip every signature at once; converting standard accounts and retiring the legacy scheme come later. Tron took the additive route: draft proposal TIP-899, written in late June, would introduce Falcon and Dilithium signatures across transactions, block production, node communication and its virtual machine, with each scheme activated through on-chain governance. Aptos favors the conservative choice, advancing AIP-137 and the SLH-DSA-SHA2-128s standard, which rests on SHA-256. Expert judgment on urgency splits. Quantum-security analyst Marin Ivezic argued in an October 5 report that retiring legacy algorithms is harder than adding new ones, and that assets left on old cryptography would keep a network exposed even after quantum-resistant signatures ship. Starkware co-founder Eli Ben-Sasson has warned the threat could arrive sooner than expected and doubts Ethereum's transition will land on time; his company has weighed building its own mainnet outside layer-2 scaling. Coinbase cryptographer Yehuda Lindell rejects the alarm, saying decades of elliptic curve cryptography show no evidence of weakening and that collapse claims without proof can stoke fear. Sizing is the shared cost problem, since larger signatures raise the processing load that flows into gas fee levels.

COINOTAG's reading: December 2029 functions as a scope statement, not a schedule, and the August pivot away from Poseidon is the more consequential fact in the file. Reusing audited SHA and BLAKE standards shortens the audit and tooling path a bespoke function would have demanded. The binding constraint is decommissioning rather than invention: BLS and elliptic curve signatures would have to be retired across staking deposits, withdrawal credentials and older wallets, and assets left on legacy keys would keep the network exposed however fast new signing ships. The mitigation on record is thin. An emergency-recovery hard fork remains a studied concept with no activation plan, and the nearest concrete milestone on Ethereum's calendar, the Glamsterdam Hoodi testnet activation on October 26, carries unrelated changes.