Fast Merkle Trees

The five-minute read

One action, walked through

1. Open BIP 98 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: In many applications it is useful to prove membership of a data element in a set without having to reveal the entire contents of that set.
3. Name the object that changes: CVE.
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 98 at the status the text itself states: Draft.
• The object that has to change is CVE. A neighbouring document with a similar name is not this one.
• Activation is a separate mechanism from the opcode or the sighash. This page does not pick a height.

What happened after the paper

The source marks this draft. It is not a live consensus rule just because it has a number. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• Which bytes become invalid under Fast Merkle Trees, and which old transactions stay valid?
• Is enforcement in consensus, or only in the mempool policy of one client?
• Which of these objects does the text actually define: CVE?

Terms

BIP 98

The public text titled Fast Merkle Trees.

Draft

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

The problem the paper names

Bitcoin script and block validity only change when a soft fork says an old pattern is now invalid. Without that rule, every node is free to accept what this document wants to reject.

What the design proposes

• In many applications it is useful to prove membership of a data element in a set without having to reveal the entire contents of that set.
• The Merkle hash-tree, where inner/non-leaf nodes are labeled with the hash of the labels or values of its children, is a cryptographic tool that achieves this goal.
• Bitcoin uses a Merkle hash-tree construct for committing the transactions of a block into the block header.

How the mechanism is specified

• Taken from the specification, the next constraint is: The Merkle hash-tree, where inner/non-leaf nodes are labeled with the hash of the labels or values of its children, is a cryptographic tool that achieves this goal.
• Locate CVE in BIP 98 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 soft fork does not bind a node that never upgrades. It binds the nodes that enforce the new rejection.
• Activation is a separate mechanism from the opcode or the sighash. This page does not pick a height.
• The source marks this draft. It is not a live consensus rule just because it has a number.

Why a venture studio still reads it

Use BIP 98 when a pitch says 'Fast Merkle Trees' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.