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All You Need is DAG

DAG-Rider. Idit Keidar, Eleftherios Kokoris-Kogias, Oded Naor and Alexander Spiegelman.

Replicas reliably broadcast proposals into a round-structured DAG. Once the DAG is local, each replica can read a total order off it without another round of consensus messages. The paper is the asynchronous, optimally resilient version of that idea.

DAG-Rider has two layers. Reliable broadcast builds a round-by-round DAG of proposals. Each replica then reads a total order off its local DAG and sends no further consensus messages. The setting is asynchronous. The committee is known. Fewer than one third may be faulty.
Evidence
Primary paper
Re-measured
No
Assumptions
4
Records linked
4

Code

Source, repository, and what is actually hosted

  • arXiv:2102.08325https://arxiv.org/abs/2102.08325
  • 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.

  1. Claim 01 · Paper model

    The DAG is the memory

    A vertex names a quorum of vertices from the previous round. That quotation is how a replica proves it saw a causal history. There is no separate block header doing this job.

  2. Claim 02 · Paper model

    Order is local

    Once the DAG contains the right vertices, every honest replica computes the same total order without another vote. If a protocol still runs a BFT instance per vertex, it is a different design.

  3. Claim 03 · Paper model

    Asynchrony is the point

    The paper does not assume a known message-delay bound for safety or for its liveness claim. That is why the commit rule is more patient than a partially synchronous protocol.

  4. Claim 04 · Paper model

    Fairness means inclusion

    Proposals from correct replicas are eventually ordered. The word is about censorship by the commit rule, not about equal fees.

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 The DAG is the memory

    Observation

    What the study says

    A vertex names a quorum of vertices from the previous round. That quotation is how a replica proves it saw a causal history. There is no separate block header doing this job.

    Model

    What has to hold

    A known set of replicas, with reliable authenticated channels in the model.

    Falsifier

    What would retire it

    What happens to a slow honest replica's proposal?

  2. 02 Order is local

    Observation

    What the study says

    Once the DAG contains the right vertices, every honest replica computes the same total order without another vote. If a protocol still runs a BFT instance per vertex, it is a different design.

    Model

    What has to hold

    Replicas store the DAG they need. The paper is not a garbage-collection design.

    Falsifier

    What would retire it

    What happens to a slow honest replica's proposal?

  3. 03 Asynchrony is the point

    Observation

    What the study says

    The paper does not assume a known message-delay bound for safety or for its liveness claim. That is why the commit rule is more patient than a partially synchronous protocol.

    Model

    What has to hold

    A known set of replicas, with reliable authenticated channels in the model.

    Falsifier

    What would retire it

    Is the committee fixed in the paper's sense?

  4. 04 Fairness means inclusion

    Observation

    What the study says

    Proposals from correct replicas are eventually ordered. The word is about censorship by the commit rule, not about equal fees.

    Model

    What has to hold

    A known set of replicas, with reliable authenticated channels in the model.

    Falsifier

    What would retire it

    Is the committee fixed in the paper's sense?

03 Sequence

One action, as an operating tape

  1. 01A replica reliably broadcasts a vertex that points at a quorum of the prior round.
  2. 02Honest replicas eventually hold those vertices and the history they point at.
  3. 03The commit rule selects a wave of the DAG once enough structure is visible.
  4. 04The causal history of the committed vertex is ordered deterministically.
  5. 05A slow but correct replica is still included, which is the fairness claim.

04 Load-bearing

The argument, and where a pitch drops it

  1. Zero extra messages is the claim to test

    The cut

    The abstract's 'all you need is DAG' means the ordering layer adds no communication. A system diagram with a DAG plus a HotStuff box has not implemented the paper.

    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 DAG in a diagram is not this protocol unless the commit rule is the one the paper defines.

  2. Optimal is asymptotic

    The cut

    Optimal resilience, amortised communication and time are complexity claims. They are not a transactions-per-second figure. Bullshark is what you read for the common-case complaint against this paper.

    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 known committee is assumed. Open membership is outside the paper.

05 Register

What has to be true

  • Model · Not re-measured

    A known set of replicas, with reliable authenticated channels in the model.

  • Stake and threshold · Not re-measured

    Fewer than one third Byzantine.

  • Model · Not re-measured

    Reliable broadcast actually delivers the properties the commit rule uses.

  • Model · Not re-measured

    Replicas store the DAG they need. The paper is not a garbage-collection design.

06 Divergence

What happened after the paper

DAG-Rider is the citation for asynchronous DAG consensus with a local commit rule. Narwhal, Tusk and Bullshark are the follow-ons. A chain that says 'we use a DAG' still owes the commit rule and the fault assumption.

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

  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

The problem it names

Classical BFT spends messages both to disseminate a proposal and to agree on its place. DAG-Rider separates those. Dissemination builds the DAG. Ordering is a local interpretation of the DAG.

What the design proposes

  • Each round, a replica broadcasts a vertex that points at a quorum of vertices from the previous round.
  • Reliable broadcast keeps the DAG consistent enough that honest replicas eventually share a causal history.
  • A commit rule walks that history. No extra votes are sent to decide the order.

How the mechanism is specified

  • Asynchrony is the network assumption. The protocol does not wait for a known bound on delay in order to stay safe.
  • The resilience claim is the usual one third. Optimal amortised communication is a complexity claim in the paper, not a throughput number for a product.
  • Fairness here means a correct replica's proposals are eventually ordered, not that users pay the same fee.

What this page does not treat as proven

  • A known committee is assumed. Open membership is outside the paper.
  • Practical garbage collection and the happy path under synchrony are what later papers, including Bullshark, add.
  • A DAG in a diagram is not this protocol unless the commit rule is the one the paper defines.

Why the desk still reads it

Ask whether ordering needs any messages beyond building the DAG. If the design still runs a separate PBFT on every vertex, it is not DAG-Rider.

09 Lexicon

Terms, opened into the record

Structured DAG
A round-by-round graph in which each vertex cites a quorum of the previous round.
Local commit
A total order computed from the DAG alone, with no extra consensus round.

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

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.