Ethereum’s Fusaka upgrade will activate on December 3 and implement a series of changes designed to increase rollup 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 scheduled for later this month and January.
Fusaka is named after the star Fulu (“auxiliary road”) and the city of Osaka (“slope or hill”), continuing Ethereum’s convention of linking a star and a city.
Editor’s note: Inclined Side Road is a playful nod to the Fulu + Osaka mash-up, not an official translation.
Data availability gets a layer of scale
The central technical shift is PeerDAS, formalized in EIP-7694. The protocol allows nodes to verify that blob data exists by sampling small chunks instead of downloading entire blobs.
That removes a scaling bottleneck introduced by EIP-4844 and creates a path to increase blob throughput by about an order of magnitude over time.
Higher blob capacity directly translates into cheaper transaction fees for layer two, because rollups compress user transactions into blobs and post them to Ethereum’s base layer.
Fusaka also increases the default gas limit per block to 60 million gas, compared to the 30 million configuration set after the merger.
The increase doubles the L1 block gas budget, creating more room for both standard transactions and blob processing.
Two follow-up “Blob Parameter Only” forks, BPO1 on December 9 and BPO2 on January 7, will adjust blob parameters without additional code changes, further expanding capacity.
The blob fee market has been rewired
EIP-7918 ties the minimum blob base fee to execution gas, preventing blob prices from falling to near zero while L1 gas remains expensive.
The change keeps the data availability market economically rational as usage fluctuates. Previously, blob fees could differ widely from execution costs, creating arbitrage opportunities and distorting the overall economy.
A series of related Ethereum Improvement Proposals (EIPs) tighten several heavy opcodes and transaction limits. The EIPs are 7823, 7825, 7883 and 7934.
The proposals limit ModExp precompilation input sizes, increase gas costs, introduce a cap on transaction gas limits, and enforce a limit on the size of RLP blocks. These limitations reduce the surface area of denial-of-service attacks and make client workloads more predictable in the worst-case scenario.
Developer tools and cryptographic hooks
EIP-7939 introduces a leading zero opcode that makes bit manipulation, integer logarithms, and randomness logic cheaper and easier on-chain.
The addition will benefit DeFi protocols and cryptographic contracts that rely on efficient bitwise operations.
Deterministic proposer lookahead, specified in EIP-7917, gives validators a fixed schedule of who will propose blocks.
MEV relay and stakeout operators can use the more accurate timeline to coordinate more safely and efficiently, reducing uncertainty in block production workflows.
EIP-7951 adds a native precompile for the secp256r1 curve, the same cryptographic standard used by Apple Secure Enclave, Android Keystore, and WebAuthn.
Wallets and smart account systems can now verify password-style signatures directly on Ethereum, enabling FaceID and TouchID authentication flows without custom bridges or circuits.
The precompile removes a major bottleneck for consumer-facing applications that rely on biometric hardware.
Immediate and phased rollout
Fusaka will activate at block height on December 3, with the first blob parameter adjusted six days later. BPO2 lands on January 7, completing the initial capacity expansion.
The phased deployment allows node operators and rollup teams to monitor blob usage and client performance before incrementing the next parameter.
The upgrade does not introduce any changes to the consensus layer in staking or validator incentives. All adjustments focus on execution layer throughput, gas mechanics, and developer primitives.
Validators running updated clients will handle the new opcodes and blog logic without changes to their staking settings.
Fusaka represents Ethereum’s most throughput-oriented upgrade since EIP-4844 introduced blobs in March 2024. The fork doubles block gas capacity, scales data availability sampling, and adds cryptographic hooks for mainstream authentication hardware.
The combination positions Ethereum to absorb higher rollup activity without commensurate rate increases, while giving developers new primitives for on-chain computation and user onboarding.
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