EIP-7883 — ModExp Gas Cost Increase

EIP-7883ModExp Gas Cost Increase

Runnable

Live on the hosted MCP — free on Fusaka (mainnet today) and Amsterdam.

Fusaka (mainnet) · AmsterdamRuns withrun_bytecode

Website twin: exploration on feelyourprotocol.org

What became possible

How are ModExp gas costs changing with Fusaka?

EIP-7883 recalibrates the ModExp precompile (0x05) gas formula so cost better reflects real work — especially for larger exponents. EIP-7823 (same fork) tightens input bounds. The new formula is live on Fusaka (current mainnet EL).

The MCP server runs caller-supplied bytecode that invokes ModExp (typically a CALL to 0x05 with the standard ABI: three 32-byte length headers plus B, E, M bodies). Run on Fusaka to price today’s mainnet; compare Pectra vs Fusaka to see the repricing — or sweep input sizes on Fusaka alone to understand the curve.

Try asking your agent

The hosted MCP is live (Connect). Copy a prompt into your agent — each quote is self-contained.

Job

Fusaka

On Fusaka, CALL ModExp at 0x05 with base, exponent, and modulus each 32 bytes of 0x02 — how much gas does the CALL use?

Look forgasUsed for the CALL to 0x05

Agent will likely call run_bytecode

Lesson

Pectra vs Fusaka

On Pectra then Fusaka, run the same 32-byte ModExp CALL (base, exponent, and modulus each 32 bytes of 0x02) — how much did gas increase?

Look forthe same payload costing more on Fusaka

Agent will likely call run_bytecode

Check

Fusaka

On Fusaka, CALL ModExp at 0x05 with a 4096-byte modulus — does EIP-7823 reject the input?

Agent will likely call run_bytecode

What the server does

1. 1

   Discover support

   Confirm the 7883 catalog entry; read the ModExp input layout.

2. 2

   Run bytecode

   Execute CALL bytecode on fusaka (or pectra then fusaka for a compare).

Fork caveat

EIP-7883 introduced at Fusaka (current mainnet). For before/after, run the same bytecode on pectra (predecessor), then fusaka, and diff gasUsed. The probe derives this pair from eipIntroductions. A Fusaka-only run is enough when you only need today’s ModExp cost.

Twins and spec

Website exploration

EIP-7883 on feelyourprotocol.org

Canonical spec

EIP-7883

Fork page

Current mainnet — Fusaka

EIP catalogue

Coverage

EIP-7883 MCP Catalogue Changelog

EIP-7883 MCP Catalogue Changelog

1. v0.32026-09-17Live on Fusaka; Fusaka-only pricing plus Pectra compare; dropped duplicate fork name.
2. v0.22026-09-02Status is public-launch ready — no local / self-host framing.
3. v0.12026-08-31Initial catalogue page — ModExp gas repricing, Pectra/Fusaka compare, twin link.