| Our study lies in two areas of cryptographic protocols. The first area is anonymity, where we outline a protocol for anonymous communications supporting revocability and pseudonyms, making it possible to have anonymous yet stateful communications but also preventing malicious uses by having a possible (under certain conditions) revocation system. This is accomplished by registering a pseudonym-key pair using fair blind signatures, without revealing the pseudonym to the registering entity, but keeping sufficient information so that the pseudonym can later be revoked. This protocol has several potential uses, where not only anonymity is required, but a sense of reputation is also desired, and the possibility of revocation is either needed as a safeguard or part of the application itself.;The second area is electronic voting, where we first establish some hybrid voting protocol and analyze the security and usefulness of similar protocols. The novel aspect of this protocol is that is uses both paper and electronic ballots, and it supports auditing of the electronic ballots using a sample of the paper-ballots. This has the benefit of not requiring a full recount yet still having another level of security for the electronic ballots. This feature is developed having the voting device print the re-encrypted vote on the paper-ballots, which then can be used to check the correctness of the original encryption, without reducing the privacy of the voters.;Lastly, we design an electronic voting protocol supporting write-in ballots, which can also be used in other voting systems that traditionally could not support write-in protocols. It satisfies both uncoercibility and verifiability, among other key requirements, and does not require any computational power from the voter, which makes it the first such protocol. |
