The introduction of Blockchain technology has led to the idea of Decentralized Autonomous Organizations.
(DAOs). DAOs enable decentralized and transparent collective wealth, allowing groups of individuals to pool their funds for collective management. DAOs rely on complex smart contracts to function. Despite Bitcoin being the most popular Blockchain, its simple smart contracts make DAO unfeasible. This thesis presents a DAO structure that addresses the challenge of DAOs on Bitcoin. The system utilizes threshold signatures to allow anyone to create Bitcoin wallets jointly controlled by a group. The system is implemented as an Android application and relies on no central party, allowing the system to be used by anyone worldwide. Our experiments show that our system is practical for real-world use for groups of 50 members. Joining an organization in the system and creating a transaction to spend funds can be done in under a minute. Further research is required to determine how far the system can scale while being practical.

In this paper, we consider Byzantine reliable broadcast on partially connected networks using signatures. Byzantine reliable broadcast in partially connected and authenticated networks can be achieved by combining two algorithms, Gabriel Bracha's double-echo broadcast protocol and Danny Dolev's reliable communication protocol. Bracha's algorithm allows for Byzantine reliable broadcast in fully connected networks, while Dolev's algorithm can be used to provide reliable communication in networks which are atleast $2f+1$-connected, where $f$ is the number of Byzantine nodes. For Byzantine reliable broadcast in partially connected networks, Bracha's algorithm can be used with Dolev's algorithm providing an abstraction of a fully connected network. We show how signatures can be used to lower the connectivity requirement to $f+1$ and lower the message complexity. We also show how aggregate or multi-signatures can be used to lower bandwidth used by the algorithm. When compared to the state-of-the-art Bracha-Dolev without signatures, our protocol has a message complexity which 20 times lower (N=60,f=6).