FruitChains - ETH ZReferences •Bitcoin / Blockchain •Nakamoto, Bitcoin: A peer-to-peer...
Transcript of FruitChains - ETH ZReferences •Bitcoin / Blockchain •Nakamoto, Bitcoin: A peer-to-peer...
FruitChainsA Fair Blockchain
A single Block
Data: B
nonce
Blockchain
Genesisblock
…Data: A
nonce
Data: B
nonce
Add a block
Data: A
nonce
Data: B
nonce
Data: C
nonce
Data: C
nonce
Data: C
nonce
Data: C
noncePointer, Nonce and Data: C
solves the crypto puzzle
Distributed Setting
Genesisblock …
Data: A
nonce
Data: B
nonce
Genesisblock …
Data: A
nonce
Data: B
nonce
Genesisblock …
Data: A
nonce
Data: B
nonce
Alice
Bob Carol
Branches
B C
Branches
B C
D
F
Branches
B C
D
F G
Rewards (Bitcoin)
• Block Reward
• Transaction Fees
Mining Pools
Source: https://btc.com/stats/pool
Security Properties
Chain Consistency
Alice
Bob
A B C D E
A B C F G
k
Chain Growth
A B
A B C D
Time 𝑇0
Time 𝑇1, 𝑇1 > 𝑇0
Chain Quality
A B C D E F
Selfish Mining Attack
Selfish Mining Attack
Public Chain
Private Chain
B C
D
Selfish Mining Attack
Public Chain
Private Chain
B C
D E
Selfish Mining Attack
Public Chain
Private Chain
B C
D E
F
Selfish Mining Attack
Public Chain
Private Chain
B C ED
Selfish Mining Attack (Case 2)
Public Chain
Private Chain
B C
D
Selfish Mining Attack (Case 2)
Public Chain
Private Chain
B C
D
F
𝛾: fraction of honest players that mine on block D
Expected Revenue
• Optimal Selfish mining strategies in bitcoin (2016)• By Sapirshtein, Sompolinsky, Zohar
Expected revenue
𝛾 = 0 𝛾 = 1
«Quick Fix» for Selfish Mining
𝛾 = 0.5
FruitChains: A Fair blockchain
rewardComputational Power
High-level view
B contains contains Data: A
Structure
B C ED
Structure
B C ED
Mining a Fruit/Block
Hash• Pointer to last block
• Pointer to a block far “enough” away
• Random nonce
• Hash of the set of recent fruits
• Data
JunkB
Fruit
• Verifies data
• Pointer to last block
• Pointer to a block far “enough” away
• Random nonce
• Hash of the set of recent fruits
• Data
Data
nonce
Block
• Verifies fruits
• Pointer to last block
• Pointer to a block far “enough” away
• Random nonce
• Hash of the set of recent fruits
• Data
nonce
Hash of fruits
New Reward System
B C ED
k
Security Properties
Fruit “Freshness”
B C ED
Fruit Consistency
Alice
Bob
A B C D
A B C F
E
G
Fruit Growth
A B C
A B C D
Fruit Fairness
A B C D
Why does this work?
• Selfish Mining Attack
• Fruit Flooding
Disincentivise Mining Pools
Mining Pools
Partial Solutions
FruitChains
Reward mining fruits
Conclusion
References
• Bitcoin / Blockchain• Nakamoto, Bitcoin: A peer-to-peer electronic cash system (2008)
• Pass, Seeman, Shelat, Analysis of the blockchain protocol in asynchronous networks (2017)
• Selfish Mining Attack• Eyal, Sirer, Majority is not enough: Bitcoin mining is vulnerable (2014)
• Sapirshtein, Sompolinsky, Zohar, Optimal Selfish mining strategies in bitcoin (2016)
• FruitChains• Pass, Shi, FruitChains: A Fair Blockchain (2017)