ModExp Gas Cost

The five-minute read

One action, walked through

1. Open EIP 2565 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: Defines the gas cost of the ModExp (0x00..05) precompile.
3. Name the object that changes: FORK_BLOCK_NUMBER, calculate_multiplication_complexity, base_length.
4. Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

The argument, unpacked

What has to be true

• You are implementing EIP 2565 at the status the text itself states: Final.
• The object that has to change is FORK_BLOCK_NUMBER, calculate_multiplication_complexity, base_length. A neighbouring document with a similar name is not this one.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.

What happened after the paper

The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• What does ModExp Gas Cost charge, reject, or redefine on the first touch versus a later one?
• Does a reverted subcall roll the change back?
• Can you point at the object in a client: FORK_BLOCK_NUMBER, calculate_multiplication_complexity, base_length?

Terms

EIP 2565

The public text titled ModExp Gas Cost.

Final

The document's own label for how finished the text is. It is not a market fact.

The problem the paper names

An underpriced or ambiguous EVM rule is not a feature. It is a block that takes longer than the gas limit claimed, or a client that disagrees about the result.

What the design proposes

• Defines the gas cost of the ModExp (0x00..05) precompile.
• To accurately reflect the real world operational cost of the ModExp precompile, this EIP specifies an algorithm for calculating the gas cost.
• This algorithm approximates the multiplication complexity cost and multiplies that by an approximation of the iterations required to execute the exponentiation.

How the mechanism is specified

• Taken from the specification, the next constraint is: To accurately reflect the real world operational cost of the ModExp precompile, this EIP specifies an algorithm for calculating the gas cost.
• Locate FORK_BLOCK_NUMBER, calculate_multiplication_complexity, base_length in EIP 2565 and apply it to one transaction or call.
• Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

• A gas or opcode change is not a throughput benchmark. It is a relative price and a validity rule.
• Constants in the text can be superseded by a later fork. Cite the EIP number and the fork you mean.
• The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it.

Why a venture studio still reads it

Use EIP 2565 when a pitch says 'ModExp Gas Cost' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.