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Majority Is Not Enough: Bitcoin Mining Is Vulnerable

Selfish Mining. Ittay Eyal and Emin Gün Sirer.

A miner who withholds blocks and releases them to waste honest work can earn more than their share, even below 50 percent, under the paper's propagation assumptions.

A reading of the public document. Not a copy of it, and not a claim about a later network that reused the name.

A mining-pool pitch that ignores block propagation is ignoring the variable this attack turns on.
Evidence
Primary paper
Re-measured
No
Assumptions
3
Records linked
3

Code

Source, repository, and what is actually hosted

  • arXiv:1311.0243https://arxiv.org/pdf/1311.0243
  • 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 defect

    The informal claim was that a miner below half the hash power does best by publishing every block at once.

  2. Claim 02 · Paper model

    The rule

    A miner who withholds blocks and releases them to waste honest work can earn more than their share, even below 50 percent, under the paper's propagation assumptions.

  3. Claim 03 · Paper model

    How it is put together

    The attacker keeps a private chain. They publish when the public chain threatens to overtake. Honest miners split across the two tips and waste work.

  4. Claim 04 · Paper model

    Where the claim stops

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

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 defect

    Observation

    What the study says

    The informal claim was that a miner below half the hash power does best by publishing every block at once.

    Model

    What has to hold

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

    Falsifier

    What would retire it

    What share of hash power is assumed?

  2. 02 The rule

    Observation

    What the study says

    A miner who withholds blocks and releases them to waste honest work can earn more than their share, even below 50 percent, under the paper's propagation assumptions.

    Model

    What has to hold

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

    Falsifier

    What would retire it

    What share of hash power is assumed?

  3. 03 How it is put together

    Observation

    What the study says

    The attacker keeps a private chain. They publish when the public chain threatens to overtake. Honest miners split across the two tips and waste work.

    Model

    What has to hold

    It does not say a 51 percent attack is cheap.

    Falsifier

    What would retire it

    Does the deployment's relay network change gamma?

  4. 04 Where the claim stops

    Observation

    What the study says

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

    Model

    What has to hold

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

    Falsifier

    What would retire it

    Does the deployment's relay network change gamma?

03 Sequence

One action, as an operating tape

  1. 01Model miners as a share of hash power.
  2. 02Compare revenue under honest publication and under the withholding policy.
  3. 03The threshold depends on how quickly the attacker's block reaches the network.
  4. 04What share of hash power is assumed?

04 Load-bearing

The argument, and where a pitch drops it

  1. Why it is still on the desk

    The cut

    A mining-pool pitch that ignores block propagation is ignoring the variable this attack turns on.

    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 threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

  2. After the text

    The cut

    Later work studied stubborn mining and published the gamma parameter more carefully. Pools still matter because they concentrate the decision to withhold.

    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 threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

05 Register

What has to be true

  • Stake and threshold · Not re-measured

    The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.

  • Cryptography · Not re-measured

    It is not a proof that bitcoin failed.

  • Model · Not re-measured

    It does not say a 51 percent attack is cheap.

06 Divergence

What happened after the paper

Later work studied stubborn mining and published the gamma parameter more carefully. Pools still matter because they concentrate the decision to withhold.

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

  4. 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

The informal claim was that a miner below half the hash power does best by publishing every block at once.

What the design proposes

  • The attacker keeps a private chain.
  • They publish when the public chain threatens to overtake.
  • Honest miners split across the two tips and waste work.

How the mechanism is specified

  • Model miners as a share of hash power.
  • Compare revenue under honest publication and under the withholding policy.
  • The threshold depends on how quickly the attacker's block reaches the network.

What this page does not treat as proven

  • The threshold in the paper is not a universal constant. Gamma, the propagation parameter, moves it.
  • It is not a proof that bitcoin failed.
  • It does not say a 51 percent attack is cheap.

Why the desk still reads it

A mining-pool pitch that ignores block propagation is ignoring the variable this attack turns on.

09 Lexicon

Terms, opened into the record

Private chain
Blocks the attacker has mined and not yet shown.
Gamma
How the rest of the network splits when two blocks race.

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.