Set upper bounds for MODEXP

The five-minute read

One action, walked through

1. Open EIP 7823 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: Introduce an upper bound on the inputs of the MODEXP precompile.
3. Name the object that changes: MODEXP, EVMMAX, EVM.
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 7823 at the status the text itself states: Final.
• The object that has to change is MODEXP, EVMMAX, EVM. 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• Constants in the text can be superseded by a later fork.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 Set upper bounds for MODEXP 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: MODEXP, EVMMAX, EVM?

Terms

EIP 7823

The public text titled Set upper bounds for MODEXP.

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

• Introduce an upper bound on the inputs of the MODEXP precompile.
• This can reduce the number of potential bugs, because the testing surface is not infinite anymore, and makes it easier to be replaced using EVMMAX.
• The MODEXP precompile has been a source of numerous consensus bugs.

How the mechanism is specified

• Taken from the specification, the next constraint is: This can reduce the number of potential bugs, because the testing surface is not infinite anymore, and makes it easier to be replaced using EVMMAX.
• Locate MODEXP, EVMMAX, EVM in EIP 7823 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 7823 when a pitch says 'Set upper bounds for MODEXP' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.