Ethereum privacy proposal faces gas limit challenge

A September 5 proposal to modify Ethereum’s Frames transaction design (EIP‑8141) would allow certain nodes to accept privacy‑focused transactions that exceed a shared validation gas allowance. The change aims to let capable nodes process heavier transactions locally while still propagating qualifying ones within a 100,000‑gas floor.

Proposed validation floor

The draft caps signature checks and execution during the initial validation phase at 100,000 gas. This limit is intended to limit node workload and mitigate denial‑of‑service risk.

Benchmark reveals higher costs

A benchmark released on September 2 by mmjahanara measured an optimized Groth16 proof verifier at 190,628 gas, with the cryptographic pairing check alone consuming about 181,000 gas—already above the proposed allowance. The benchmark’s modeled minimums are 211,828 gas for a single‑note spend and 351,828 gas for an eight‑note spend, after adding overhead and a 20,000‑gas execution charge per nullifier.

Accounting differences

The benchmark’s accounting differs from the current EIP‑8250 companion draft, which charges fresh nonce keys to a separate state‑gas budget. While the accounting method varies, the gap between verifier execution cost and the 100,000‑gas limit remains.

Recommendations and pending adoption

The benchmark author recommends a minimum of 250,000 gas for typical optimized privacy transactions, but this recommendation has not been adopted. Even if adopted, it would still fall short of the eight‑note model total.

Implications for privacy designs

For designs such as Tornado Cash and RAILGUN, replacing off‑chain relayers with public submission would require proofs that nodes accept and forward. Allowing only some nodes to process heavier transactions does not guarantee network‑wide support. Additional proposals (EIP‑8250, EIP‑8369) address related constraints like public‑mempool limits and transaction inclusion rules.

Conclusion

The proposal offers optional flexibility at the node level, but guaranteeing public access for studied privacy designs would still require accommodating proof costs that exceed the current shared gas allowance.