  Leader Election (LE) is crucial in distributed systems and blockchain
technology, ensuring one participant acts as the leader. Traditional LE methods
often depend on distributed random number generation (RNG), facing issues like
vulnerability to manipulation, lack of fairness, and the need for complex
procedures such as verifiable delay functions (VDFs) and publicly-verifiable
secret sharing (PVSS). This Bachelor's thesis presents a novel approach to
randomized LE, leveraging a game-theoretic assumption that participants, aiming
to be chosen as leaders, will naturally avoid actions that diminish their
chances. This perspective simplifies LE by eliminating the need for
decentralized RNG. Introducing PureLottery, inspired by single-elimination
sports tournaments, this method offers a fair, bias-resistant, and efficient LE
solution for blockchain environments. It operates on the principle of two
participants competing in each match, rendering collusion efforts useless.
PureLottery stands out for its low computational and communication complexity,
suitable for smart contract implementation. It provides strong game-theoretic
incentives for honesty and is robust against adversaries, ensuring no increase
in election chances through dishonesty. The protocol guarantees that each
honest player has at least a 1/n chance of winning, irrespective of adversary
manipulation among the other n-1 participants. PureLottery can also address
related problems like participant ranking, electing multiple leaders, and
leader aversion, showcasing its versatility across various applications,
including lotteries and blockchain protocols. An open-source implementation is
made available for public use.
