This thesis examines verifiability and receipt freeness in cryptographic voting protocols in detail and points out the contradiction between these requirements. Firstly, an extensive electronic voting requirement set is clearly defined, and then the voting dilemma is described. This is followed by a suggestion of an applicable solution to overcome the voting dilemma by introducing Predefined Fake Vote (PreFote) scheme. Based on a comprehensive literature review, a classification of the existing privacy preserving approaches and a taxonomy of the existing cryptographic voting protocols extending the previous studies are provided. Thereby, a complete and secure cryptographic voting protocol satisfying all electronic voting security requirements at the same time seems non-existent. Hence, an alternative privacy preserving approach is highly needed. Pseudo-Voter Identity (PVID) scheme, proposed in the present study, is a practical and low cost one. The PVID scheme is based on RSA blind signature, and it allows recasting without sacrificing uniqueness. Furthermore, this study proposes a dynamic ballot mechanism including an extension with PreFotes. This study, wherein the PVID scheme and extended dynamic ballots with PreFotes are employed, proposes a practical, complete and secure cryptographic voting protocol over a network for large scale elections, which fulfils all of the electronic voting security requirements: privacy, eligibility, uniqueness, fairness, uncoercibility, receipt-freeness, individual verifiability and accuracy. Lastly, a method to analyse voting systems based on security requirements is suggested, and a detailed analysis of the proposed protocol, which uses this method, concludes this study.

Many e-voting techniques have been proposed but not widely used in reality. One of the problems associated with most of existing e-voting techniques is the lack of transparency, leading to a failure to deliver voter assurance. In this work, we propose a transparent, auditable, end-to-end verifiable, and mutual restraining e-voting protocol that exploits the existing multi-party political dynamics such as in the US. The new e-voting protocol consists of three original technical contributions -- universal verifiable voting vector, forward and backward mutual lock voting, and in-process check and enforcement -- that, along with a public real time bulletin board, resolves the apparent conflicts in voting such as anonymity vs. accountability and privacy vs. verifiability. Especially, the trust is split equally among tallying authorities who have conflicting interests and will technically restrain each other. The voting and tallying processes are transparent to voters and any third party, which allow any voter to verify that his vote is indeed counted and also allow any third party to audit the tally. For the environment requiring receipt-freeness and coercion-resistance, we introduce additional approaches to counter vote-selling and voter-coercion issues. Our interactive voting protocol is suitable for small number of voters like boardroom voting where interaction between voters is encouraged and self-tallying is necessary; while our non-interactive protocol is for the scenario of large number of voters where interaction is prohibitively expensive. Equipped with a hierarchical voting structure, our protocols can enable open and fair elections at any scale.