Garand from Stellar protocol team presents State Archival, a novel solution to state bloat that assigns TTL values to ledger entries, archives expired data off-chain in Merkle tries, and defends against double restore, malicious archival, and double nonce attacks. Implementation launched on mainnet in February 2025.
Stellar protocol engineer Garand discusses State Archival, a protocol solution addressing state bloat where all blockchain state must be maintained indefinitely despite one-time transaction fees. The system assigns TTL values to ledger entries with rent payments to extend them. Expired entries are archived off-chain in immutable Merkle tries while validators maintain only Merkle roots, freeing resources. The presentation covers three attack vectors: double restore attacks prevented by requiring proofs of non-inclusion for newer tries, malicious archival prevented by allowing anyone to extend TTLs or restore entries without authorization, and double nonce attacks prevented using binary fuse filters to check archived keys. The full proof system with entry deletion is code complete and expected to reach mainnet later in 2025.
