6.857 - Final Project Secure Transactions without Mining or Central Authority

In our project we implemented a system from transferring money without using Proof-of-Work, but consensus algorithms. First we implemented it using Paxos[11], that does not support Byzantine failures and needs a central authority to decide which nodes participate on the agreements. Then we reimplemented it using Stellar Consensus Protocol[2], that has no central authority and allows Byzantine nodes, given that Safety and Liveness assumptions are guarantee. The actual Stellar Network has many features that we did not implement for simplicity. While at Stellar Network anyone is allowed to be a gateway, entities that can create their own coins, our system has only one gateway. This way, there is no need to implement Distributed Exchange. Also, we only put one transaction on each slot of our ledger. This report is divided in 6 sections. Section 1 is this introduction. Section 2 gives an overview of existing models to implement a secure financial system with support to transactions. In section 3 we give an overview at Byzantine Agreements and Federated Byzantine Agreements. In section 4 we talk about how the Stellar Consensus Protocol works. Section 5 is about our implementation. Section 6 is the conclusion. We will not prove any theorem of these systems. We recommend looking at the references.