LibraryPrivacy2023Design paperCorpus record
Non-Fungible Key Bound Token
ERC 6809. Mihai Onila , Nick Zeman , Narcis Cotaie.
ERC 6809, Non-Fungible Key Bound Token. A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
Status in the source: Final. A reading of the public specification, not a copy of it and not a certification.
Non-Fungible Key Bound Token is worth reading for the rule it actually adds: A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 3
- Records linked
- 4
Code
Source, repository, and what is actually hosted
- ERC 6809https://eips.ethereum.org/EIPS/eip-6809
- The source URL is not a GitHub repository. No code remote is invented.
- Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
- Add to a reading list
01 Claim ledger
What the paper is allowed to say
Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.
Claim 01 · Paper model
The rule
A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
Claim 02 · Paper model
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.
Claim 03 · Paper model
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.
Claim 04 · Paper model
What a builder should be able to point at
An implementation either constrains NFKBT, KBT, API or it is a different design.
02 Three cuts
Observation, model, falsifier
A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.
01 The rule
Observation
What the study says
A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
Model
What has to hold
The object that has to change is NFKBT, KBT, API. A neighbouring document with a similar name is not this one.
Falsifier
What would retire it
What is covered by the signed bytes in Non-Fungible Key Bound Token?
02 What was already failing
Observation
What the study says
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.
Model
What has to hold
The object that has to change is NFKBT, KBT, API. A neighbouring document with a similar name is not this one.
Falsifier
What would retire it
Can the same signature be replayed on another chain, account, or message?
03 What the number does not mean
Observation
What the study says
The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it.
Model
What has to hold
You are implementing ERC 6809 at the status the text itself states: Final.
Falsifier
What would retire it
Which primitive does the text require: NFKBT, KBT, API?
04 What a builder should be able to point at
Observation
What the study says
An implementation either constrains NFKBT, KBT, API or it is a different design.
Model
What has to hold
The object that has to change is NFKBT, KBT, API. A neighbouring document with a similar name is not this one.
Falsifier
What would retire it
Which primitive does the text require: NFKBT, KBT, API?
03 Sequence
One action, as an operating tape
- 01Open ERC 6809 and read the status line before the examples.
- 02Write down the rule in one sentence. A fair version of that sentence is: A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
- 03Name the object that changes: NFKBT, KBT, API.
- 04Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.
04 Load-bearing
The argument, and where a pitch drops it
What the text is allowed to settle
The cut
Ethereum Request for Comment 6809 can settle the shape of Non-Fungible Key Bound Token. It cannot settle whether a later client, a later fork, or a later wallet still does this.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
What this page will not pretend
The cut
There is no benchmark, no adoption number, and no claim that the mechanism is safe outside the assumptions written in the source.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
The source marks this final. That is a statement about the text, not a promise that every wallet or node has shipped it.
05 Register
What has to be true
Model · Not re-measured
You are implementing ERC 6809 at the status the text itself states: Final.
Model · Not re-measured
The object that has to change is NFKBT, KBT, API. A neighbouring document with a similar name is not this one.
Model · Not re-measured
06 Divergence
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.
A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.
07 Pre-mortem
What to check before you use the idea
- 0 of 3 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.
08 Anatomy
The paper, in the order a builder needs
The problem it 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
- A standard interface for Non-Fungible Key Bound Tokens (NFKBT/s), a subset of the more general Key Bound Tokens (KBT/s).
- The following standardizes an API for tokens within smart contracts and provides basic functionality to the addBindings function.
- This function designates Key Wallets[^1], which are responsible for conducting a Safe Transfer[^2].
How the mechanism is specified
- Taken from the specification, the next constraint is: The following standardizes an API for tokens within smart contracts and provides basic functionality to the addBindings function.
- Locate NFKBT, KBT, API in ERC 6809 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
Why the desk still reads it
Use ERC 6809 when a pitch says 'Non-Fungible Key Bound Token' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.
09 Lexicon
Terms, opened into the record
- ERC 6809
- The public text titled Non-Fungible Key Bound Token.
- Final
- The document's own label for how finished the text is. It is not a market fact.
10 Repository
Every linked record on this page
Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.
Concepts
Protocols
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.