Chain Code Delegation

The five-minute read

One action, walked through

1. Open BIP 89 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: Chain Code Delegation (CCD) is a method for multi-signature wallets in which a privileged participant withholds BIP32 chain codes from one or more non-privileged participants, and supplies per-input scalar tweaks at signing time.
3. Name the object that changes: CCD, BIP32.
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 BIP 89 at the status the text itself states: Deployed.
• The object that has to change is CCD, BIP32. 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 deployed. 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 Chain Code Delegation?
• Can the same signature be replayed on another chain, account, or message?
• Which primitive does the text require: CCD, BIP32?

Terms

BIP 89

The public text titled Chain Code Delegation.

Deployed

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

• Chain Code Delegation (CCD) is a method for multi-signature wallets in which a privileged participant withholds BIP32 chain codes from one or more non-privileged participants, and supplies per-input scalar tweaks at signing time.
• This allows non-privileged participants to co-sign transactions without learning wallet-wide derivations, balances, or signing activity from other spending combinations.
• CCD defines the tweak exchange needed for verification and signing behavior when the signer does not possess a chain code.

How the mechanism is specified

• Taken from the specification, the next constraint is: This allows non-privileged participants to co-sign transactions without learning wallet-wide derivations, balances, or signing activity from other spending combinations.
• Locate CCD, BIP32 in BIP 89 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 deployed. 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 BIP 89 when a pitch says 'Chain Code Delegation' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.