Chainweb: A Proof-of-Work Parallel-Chain Architecture for Massive Throughput

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.

1. Claim 01 · Paper model

   One chain's hash rate is a ceiling

   Kadena's paper does not abandon proof of work. It runs many chains, each with its own blocks, so work happens in parallel.

2. Claim 02 · Paper model

   Cross-links are the braid

   A block on one chain includes hashes of recent blocks on neighbouring chains. To rewrite one chain deeply, an attacker has to keep those neighbours consistent too.

3. Claim 03 · Paper model

   The graph is fixed at a layer

   The paper describes a topology, often thought of as a Petersen graph in the public explanation, of which chains reference which. The topology is a parameter with a security meaning.

4. Claim 04 · Paper model

   Pact is the language beside the braid

   Human-readable contracts sit on this chain web. The consensus paper and the language paper answer different questions. Throughput does not make a contract correct.

5. Claim 05 · Paper model

   Confirmation is a braid depth

   A transaction is not confirmed because its own chain buried it. Neighbouring chains have to have had a chance to cite that height. Wallets that only watch one chain are under-confirming.

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.

1. 01 One chain's hash rate is a ceiling

   Observation

   What the study says

   Kadena's paper does not abandon proof of work. It runs many chains, each with its own blocks, so work happens in parallel.

   Model

   What has to hold

   Hash rate is distributed across chains roughly as the security argument expects. An idle chain is a weak link in the braid.

   Falsifier

   What would retire it

   Which chains cite which, and how deep must a citation be before a wallet accepts it?

2. 02 Cross-links are the braid

   Observation

   What the study says

   A block on one chain includes hashes of recent blocks on neighbouring chains. To rewrite one chain deeply, an attacker has to keep those neighbours consistent too.

   Model

   What has to hold

   Hash rate is distributed across chains roughly as the security argument expects. An idle chain is a weak link in the braid.

   Falsifier

   What would retire it

   Is hash rate actually present on every chain in the braid?

3. 03 The graph is fixed at a layer

   Observation

   What the study says

   The paper describes a topology, often thought of as a Petersen graph in the public explanation, of which chains reference which. The topology is a parameter with a security meaning.

   Model

   What has to hold

   Hash rate is distributed across chains roughly as the security argument expects. An idle chain is a weak link in the braid.

   Falsifier

   What would retire it

   Which chains cite which, and how deep must a citation be before a wallet accepts it?

4. 04 Pact is the language beside the braid

   Observation

   What the study says

   Human-readable contracts sit on this chain web. The consensus paper and the language paper answer different questions. Throughput does not make a contract correct.

   Model

   What has to hold

   Hash rate is distributed across chains roughly as the security argument expects. An idle chain is a weak link in the braid.

   Falsifier

   What would retire it

   Is Pact's contract model being cited, or the consensus braid? They are not the same document.

5. 05 Confirmation is a braid depth

   Observation

   What the study says

   A transaction is not confirmed because its own chain buried it. Neighbouring chains have to have had a chance to cite that height. Wallets that only watch one chain are under-confirming.

   Model

   What has to hold

   Confirmation logic in wallets waits for braid depth, not for one chain's depth alone.

   Falsifier

   What would retire it

   Is hash rate actually present on every chain in the braid?

03 Sequence

One action, as an operating tape

1. 01Miners on each chain attempt proof of work for the next block, including peer-chain hashes in the header they are hashing.
2. 02A valid block advances one chain and freezes a view of its neighbours at the cited heights.
3. 03A transaction is included on the chain that holds the relevant accounts.
4. 04As neighbouring chains cite that block and are themselves cited, the cost of reversing it grows with the whole braid, not with one chain's subsequent blocks.
5. 05A cross-chain call, if the product uses one, waits until the cited height is what the protocol treats as settled.

04 Load-bearing

The argument, and where a pitch drops it

1. Parallel proof of work is still proof of work

   The cut

   Energy is not removed. It is spread. The paper's argument is about how much hash rate an attacker needs to unwind the braid compared with a single chain. It is not an argument that hashing became cheap or green.

   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

   A fixed chain graph is a parameter. Changing it is a migration, which the paper does not do for you.

2. The topology decides the security multiplier

   The cut

   If chains only cite one neighbour, a local rewrite is easier than if each chain is tied to many. Quoting 'twenty chains means twenty times safer' without the graph is bad arithmetic. The paper's claim follows the cross-link structure.

   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

   A fixed chain graph is a parameter. Changing it is a migration, which the paper does not do for you.

3. Load does not balance itself

   The cut

   A hot contract on one chain does not automatically spill onto the others. Sharding of state has to be designed in the accounts. A single-chain traffic jam inside a braid is still a jam.

   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 historic PDF Kadena-ConsensusWhitePaper-Aug2016.pdf is the earlier private-chain note. Do not mix the citations.

05 Register

What has to be true

• Cryptography · Not re-measured

  Hash rate is distributed across chains roughly as the security argument expects. An idle chain is a weak link in the braid.

• Data · Not re-measured

  Peers' headers are available. A cross-link to a header nobody can fetch is not a commitment.

• Model · Not re-measured

  Miners include the cross-links the protocol requires. A client that ignores missing links is not following the paper.

• Model · Not re-measured

  Confirmation logic in wallets waits for braid depth, not for one chain's depth alone.

06 Divergence

What happened after the paper

Kadena ran a public Chainweb with Pact contracts. The number of chains and the exact topology are parameters of the deployed network. The 2018 paper is the braiding argument. Measured throughput and miner distribution are facts about the deployment, and they move.

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

1. Kill test 1Which chains cite which, and how deep must a citation be before a wallet accepts it?
2. Kill test 2Is hash rate actually present on every chain in the braid?
3. Kill test 3What does a user do when one chain is congested and the others are idle?
4. Kill test 4Is Pact's contract model being cited, or the consensus braid? They are not the same document.
5. 0 of 4 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

09 Lexicon

Terms, opened into the record

Braid

The structure formed when parallel chains commit to each other's recent headers.

Cross-link

A hash of a peer chain's block, placed in this chain's header, so the two histories constrain each other.

Braid depth

How far neighbouring chains have advanced since a block, which is the paper's notion of confirmation.

Pact

Kadena's contract language. It runs on the braid. It is not the consensus proof.

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.

11 Related

The next papers, as theses

• Solana · 2018

  Solana: A new architecture for a high performance blockchain

  Yakovenko's design note for a ledger that encodes the passage of time as a verifiable hash chain, called Proof of History, so that validators spend less effort agreeing on order.

• Polkadot · 2016

  Polkadot: Vision for a heterogeneous multi-chain framework

  Wood's 2016 vision paper: a relay chain that provides shared security and a queue of cross-chain messages, with parachains that keep their own state transition. It is a vision paper. The live protocol has a specification of its own.