LibraryConsensus2016Design paperCorpus record
FruitChains: A Fair Blockchain
FruitChains. Rafael Pass and Elaine Shi.
Nakamoto consensus can pay a minority coalition more than its share of hash power, which is the selfish-mining observation. FruitChains records transactions in 'fruit' that hang off the chain, and pays out over a window so honest hash power gets roughly honest rewards.
FruitChains keeps Nakamoto's honest-majority security and changes the reward. Transactions sit in fruit that are easier to find than blocks. Rewards are averaged over a window so a minority of hash power cannot systematically earn more than its share by withholding.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 4
- Records linked
- 4
Code
Source, repository, and what is actually hosted
- ePrint 2016/916https://eprint.iacr.org/2016/916
- 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.
Claim 01 · Paper model
Selfish mining is the defect
The paper starts from the fact that a coalition can do better than its hash-power fraction by strategic withholding. Fairness is defined against that, not against a feeling about pools.
Claim 02 · Paper model
Fruit versus blocks
Fruit carry transactions and are mined at a lower difficulty. Blocks form the chain that decides which fruit are stable. The two objects are not interchangeable.
Claim 03 · Paper model
Approximate, over a window
The guarantee is that a long enough segment pays an honest coalition nearly its fraction. It is not a promise about the next block, and it is not exact.
Claim 04 · Paper model
Pools are a consequence, not the goal
Lower variance makes solo mining less painful. The paper says this lessens the need for pools. It does not abolish coordination among miners who want to reorder transactions.
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.
01 Selfish mining is the defect
Observation
What the study says
The paper starts from the fact that a coalition can do better than its hash-power fraction by strategic withholding. Fairness is defined against that, not against a feeling about pools.
Falsifier
What would retire it
Over what window is fairness claimed?
02 Fruit versus blocks
Observation
What the study says
Fruit carry transactions and are mined at a lower difficulty. Blocks form the chain that decides which fruit are stable. The two objects are not interchangeable.
Falsifier
What would retire it
What is the fruit, and what is the block?
03 Approximate, over a window
Observation
What the study says
The guarantee is that a long enough segment pays an honest coalition nearly its fraction. It is not a promise about the next block, and it is not exact.
Falsifier
What would retire it
What is the fruit, and what is the block?
04 Pools are a consequence, not the goal
Observation
What the study says
Lower variance makes solo mining less painful. The paper says this lessens the need for pools. It does not abolish coordination among miners who want to reorder transactions.
Model
What has to hold
Parameters, including the window, set as the paper requires for the approximation.
Falsifier
What would retire it
Is the citation used to justify a fee or a yield? It should not be.
03 Sequence
One action, as an operating tape
- 01Miners search for fruit and for blocks, at different difficulties.
- 02A fruit hangs off a recent block and carries transactions.
- 03A later block stabilises which fruit count.
- 04Rewards over a segment of length tied to the security parameter are shared so that honest hash power is paid approximately in proportion.
- 05A coalition below half the hash power cannot, in the theorem, gain more than a small factor by deviating.
04 Load-bearing
The argument, and where a pitch drops it
Fair is a defined word
The cut
Outside the paper, fair often means 'I should have been paid'. Inside the paper it means a fraction of hash power receives about that fraction of block rewards in a long window, with high probability. Do not import the wider word.
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
Fairness in the paper is about block rewards, not about transaction ordering or MEV.
MEV is a later problem
The cut
The 2016 argument is about withholding and reward variance. A miner who includes the block honestly and still reorders the fruit's transactions for private gain is not the attacker this theorem bounds.
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
Fairness in the paper is about block rewards, not about transaction ordering or MEV.
05 Register
What has to be true
Stake and threshold · Not re-measured
Honest majority of hash power for the Nakamoto-style safety claims.
Model · Not re-measured
Parameters, including the window, set as the paper requires for the approximation.
Cryptography · Not re-measured
Rewards and fees are actually distributed the way the fairness proof assumes.
Network · Not re-measured
The hash function and the network model match a longest-chain argument.
06 Divergence
What happened after the paper
FruitChains is the standard citation when a design claims to have fixed miner fairness. Check whether the design pays over a window and separates fruit from blocks. A new name for the longest chain does not inherit the theorem.
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
- 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
If a miner can earn more by withholding blocks than by publishing them, the incentive story of the longest chain is incomplete. The paper wants approximate fairness: a fraction of the hash power should get about that fraction of the rewards.
What the design proposes
- Fruit are easier to mine than blocks and carry the transactions.
- Blocks still form a chain and also stabilise which fruit count.
- Rewards are spread across a window of the chain rather than paid only to the block finder.
How the mechanism is specified
- The fairness claim is approximate, over a long enough segment, and assumes an honest majority of hash power.
- The paper also argues that lower reward variance reduces the need to join a pool. That is a consequence it states, not a measurement of later pools.
- Consistency and liveness are meant to match Nakamoto under honest majority.
What this page does not treat as proven
Why the desk still reads it
When someone says miners are paid 'fairly', ask fair against which deviation. FruitChains answers selfish withholding. It does not answer a builder who reorders transactions inside an honest block.
09 Lexicon
Terms, opened into the record
- Fruit
- A lower-difficulty record that carries transactions and is later stabilised by the chain.
- Approximate fairness
- An honest coalition's reward share stays close to its hash-power share over a long segment.
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.
Papers
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.