Lecture 27: Bitcoin (Part 2)

Bitcoin Review

Proof of Work

(True/False) In Bitcoin Proof-of-Work, if the hash function isn’t one-way then an attacker can always win by bruteforcing a valid pre-image.

Proof of Work Example

Proof of Work Security

In Bitcoin, Proof-of-Work (PoW) requires miners to find some random number n such that Hash(block || n) has a certain number of zeroes in it. What would happen if instead, miners had to find Hash(n) for which this held?

Consensus & Mining

(True/False) Even if the network eventually switches to an alternate, longer chain, a miner will still receive a mining award

Mining pools

Why might having large mining pools be worrysome?

Anonymity and Conclusions

If someone bought something from you over Bitcoin, how could you track their future transactions?

Note: We won’t have time to cover certificate transparency, but for those interested see here