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Standard Interface Detection
ERC 165. Christian Reitwießner , Nick Johnson , Fabian Vogelsteller , Jordi Baylina , Konrad Feldmeier , William Entriken.
ERC 165, Standard Interface Detection. Creates a standard method to publish and detect what interfaces a smart contract implements.
Status in the source: Final. A reading of the public specification, not a copy of it and not a certification.
Standard Interface Detection is worth reading for the rule it actually adds: Creates a standard method to publish and detect what interfaces a smart contract implements.
The five-minute read
The rule
Creates a standard method to publish and detect what interfaces a smart contract implements.
What was already failing
A signature that does not commit to what the user saw can be replayed into a different spend, a different chain, or a different message.
What the number does not mean
The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it.
What a builder should be able to point at
An implementation either constrains ABI, XOR or it is a different design.
One action, walked through
- Open ERC 165 and read the status line before the examples.
- Write down the rule in one sentence. A fair version of that sentence is: Creates a standard method to publish and detect what interfaces a smart contract implements.
- Name the object that changes: ABI, XOR.
- 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 the text is allowed to settle
Ethereum Request for Comment 165 can settle the shape of Standard Interface Detection. It cannot settle whether a later client, a later fork, or a later wallet still does this.
What this page will not pretend
There is no benchmark, no adoption number, and no claim that the mechanism is safe outside the assumptions written in the source.
What has to be true
- You are implementing ERC 165 at the status the text itself states: Final.
- The object that has to change is ABI, XOR. A neighbouring document with a similar name is not this one.
- Wallet support is not the same as consensus validity.
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 is covered by the signed bytes in Standard Interface Detection?
- Can the same signature be replayed on another chain, account, or message?
- Which primitive does the text require: ABI, XOR?
Terms
- ERC 165
- The public text titled Standard Interface Detection.
- Final
- The document's own label for how finished the text is. It is not a market fact.
The problem the paper names
A signature that does not commit to what the user saw can be replayed into a different spend, a different chain, or a different message.
What the design proposes
- Creates a standard method to publish and detect what interfaces a smart contract implements.
- How a contract will publish the interfaces it implements 3.
- How to detect if a contract implements any given interface For some "standard interfaces" like the ERC-20 token interface, it is sometimes useful to query whether a contract supports the interface and if yes, which version of the interface, in order to adapt the way in which the contract is to be interacted with.
How the mechanism is specified
- Taken from the specification, the next constraint is: How a contract will publish the interfaces it implements 3.
- Locate ABI, XOR in ERC 165 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 signature scheme is not a privacy system. It hides the signer only if the protocol says so.
- Wallet support is not the same as consensus validity.
- 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 ERC 165 when a pitch says 'Standard Interface Detection' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.
This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.
Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.
