Bitcoin Selfish Mining Marie Vasek Secure Electric Commerce (some - - PowerPoint PPT Presentation

Bitcoin Selfish Mining

Marie Vasek Secure Electric Commerce

(some slides heavily inspired by Dr. Moore)

Marie Vasek Secure Electric Commerce

B i t c

• i

n T e m p

• r

a r y b l

• c

k ‐ w i t h h

• l

d i n g a t t a c k s

Bitcoin Selfish Mining

Blockchain

Blockchain

Blockchain

Orphaned Blocks

• But, what happens when two blocks are found

around the same time?

• https://blockchain.info/charts/n-orphaned-blocks

51% attack

• Steal coins from existing addresses?
• Suppress some transactions?
• from the blockchain?
• from the p2p network?
• Change the block reward?
• Destroy confidence in Bitcoin?
• https://blockchain.info/pools

51% Attack IRL

• CoiledCoin — killed by a 51% attack in Jan 2012.
• Eligius Mining Pool refused any transactions
• GHash.io — reached over 50% of Bitcoin mining

power in 2014. Committed to never again.

Key point

With selfish mining, X% of mining power can gain more than X% of the power/revenue/etc if X ≥1/3.

Only then, announce chain to network.

BYOBlockchain?

BYOBlockchain?

Detecting Selfish Mining

• Detect lots of orphaned blocks
• Detect lots of abnormally close blocks timing

But, can we do better?

• Stubborn mining: refines selfish mining to earn

more $$

• Refined selfish mining: refines exactly when to

release the new chain

Sources

• Bitcoin and Cryptocurrency Technologies Ch. 5
• Eyal, Ittay, and Emin Gün Sirer. "Majority is not enough:

Bitcoin mining is vulnerable." Financial Cryptography and Data Security. Springer, 2014. 436-454.

• Sapirshtein, Ayelet, Yonatan Sompolinsky, and Aviv Zohar.

"Optimal selfish mining strategies in Bitcoin.” Financial Cryptography and Data Security. Springer, 2016.

• Nayak, Kartik, Srijan Kumar, Andrew Miller, and Elaine Shi.

“Stubborn Mining: Generalizing Selfish Mining and Combining with an Eclipse Attack.” IEEE Euro S&P. 2016.