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)

s k c a t t a g n i d l o h h t i w ‐ k c o l b y r a r o p m e T n i o c t i B Bitcoin Selfish Mining Marie Vasek Secure Electric Commerce

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.

BYOBlockchain? Only then, announce chain to network.

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.