PoW Based Distributed Cryptography with No Trusted Setup

Explore a comprehensive lecture on Proof-of-Work (PoW) based distributed cryptography without trusted setup, delving into Bitcoin's design principles and their differences from traditional multi-party computation. Learn about the concept of majority in terms of computing power, the verification process through Proofs of Work, and Bitcoin's implementation of the bulletin board. Examine the challenges in Bitcoin's solution and Satoshi's approach, as well as the motivation behind starting from scratch. Gain insights into the "Bitcoin network model," the modeling of computing power, and the main results of the research. Discover the key tool of a "PoW-based secure broadcast protocol" and understand its implications for adversarial behavior in the network. Analyze the importance of challenges not being known in advance for Proofs of Work and explore potential solutions and their associated problems in this cutting-edge cryptographic discussion.

Intro
Bitcoin main design principle
Difference from the MPC literature
If "majority" is defined in terms of computing power
How is the computing power verified? Proofs of Work (Pows)
Proofs of Work - security
Bitcoin's implementation of the bulletin board
Problems with Bitcoin's solution
Satoshi's solution
Natural idea: start from scratch
Motivation
What is the "Bitcoin network model"?
Modeling computing power
Summary of our results (2/2)
Main tool: a "PoW-based secure broadcast protocol"
The adversary can send a bounded number of messages We assume that several parties can broadcast their messages at the same time.
Observation Proofs of Work make sense only when the challenge is not known in advance. Consider the following protocol
Idea: let every party Pi broadcast her challenger
A problem with this solution What if the adversary ignores r; of some honest party?