Ethereum’s Fusaka upgrade will activate on December 3, rolling out a suite of changes designed to increase stacking throughput, tighten gas markets, and add native support for password-style signatures.
The fork introduces PeerDAS data availability sampling, doubles the default block gas limit, and prepares the network for blob-only parameter expansions planned for later this month and into January.
Fusaka is named after the star Fulu (âauxiliary roadâ) and the city of Osaka (âslope or hillâ), continuing Ethereum’s convention of associating a star and a city.
Editor’s note: “Sloping side road” is a playful nod to the Fulu + Osaka mash-up, and not an official translation.
Data availability benefits from a scaling layer
The central technical change is PeerDAS, formalized in EIP-7694. The protocol allows nodes to verify that blob data exists by sampling small chunks rather than downloading entire blobs.
This removes a scaling bottleneck introduced by EIP-4844 and creates a way to increase blob throughput by approximately an order of magnitude over time.
Higher blob capacity directly translates into cheaper layer two transaction fees because rollups compress user transactions into blobs and publish them to Ethereum’s base layer.
Fusaka is also increasing the default gas limit per block to 60 million gas, up from the 30 million configuration set after the merge.
This increase doubles the gas budget of the L1 block, providing more room for standard transactions and blob processing.
Two âBlob Parameter Onlyâ follow-up forks, BPO1 on December 9 and BPO2 on January 7, will adjust blob parameters without additional code changes, increasing capacity.
The Blob Fee Market Reimagined
EIP-7918 ties the blob’s minimum base fee to execution gas, preventing blob prices from collapsing to near zero while L1 gas remains expensive.
This change keeps the data availability market economically rational as usage fluctuates. Previously, blob fees could deviate significantly from execution costs, creating arbitrage opportunities and distorting the economics of stacking.
A set of related Ethereum Improvement Proposals (EIPs) strengthens several heavy opcodes and transaction limits. The EIPs are 7823, 7825, 7883 and 7934.
The proposals cap ModExp’s precompilation entry sizes, increase its gas cost, introduce a transaction gas limit cap, and impose an RLP block size limit. These constraints reduce the denial of service attack surface and make worst-case client workloads more predictable.
Developer tools and cryptographic hooks
EIP-7939 introduces a leading zero counting opcode that makes bit manipulation, integer logarithms, and random logic cheaper and simpler on-chain.
This addition benefits DeFi protocols and crypto contracts that rely on efficient bit-level operations.
Deterministic anticipation of proposers, specified in EIP-7917, gives validators a fixed schedule of who will propose blocks.
MEV relays and staking operators can use a more precise schedule to coordinate more safely and efficiently, reducing uncertainty in block production flows.
EIP-7951 adds native precompilation for the secp256r1 curve, the same cryptographic standard used by Apple Secure Enclave, Android Keystore, and WebAuthn.
Smart wallets and account systems can now verify password-like signatures directly on Ethereum, enabling FaceID and TouchID authentication flows without bridges or custom circuits.
Precompilation removes a major point of friction for consumer applications that rely on biometric hardware.
Immediate and progressive deployment
Fusaka activates at the height of the block on December 3, with the first adjustment of the blob parameters being made six days later. BPO2 lands on January 7, completing the initial capacity expansion.
Phased deployment allows node operators and rollup teams to monitor blob usage and client performance before the next parameter increase.
The upgrade does not introduce consensus-level changes to staking or validator incentives. All changes target runtime layer throughput, gas mechanics, and developer primitives.
Validators running updated clients will process the new opcodes and blob logic without changing their staking configuration.
Fusaka represents the most throughput-focused Ethereum upgrade since EIP-4844 introduced blobs in March 2024. The fork doubles gas block capacity, adapts data availability sampling, and adds cryptographic hooks for consumer authentication hardware.
The combination allows Ethereum to absorb higher stacking activity without a commensurate increase in fees, while providing developers with new primitives for on-chain computing and user onboarding.
