Scientists have requested verifiable electronic voting schemes for many years. These schemes offer individual and universal verifiability by applying and combining complex cryptographic primitives and protocols. Electronic voting systems in use provide less or even no verifiability. Thus election authorities and voters need to trust the provider and developer of the voting system regarding the ...

We introduce the notion of privacy-preserving verifiability for security protocols. It holds when a protocol admits a verifiability test that does not reveal to the verifier about the protocol’s execution more than it needs to know to run the test. Our definition of privacy-preserving verifiability is general and applies to cryptographic protocols as well as human security protocols; however, i...

While electronic elections promise the possibility of convenient, efficient and secure facilities for recording and tallying votes, recent studies have highlighted inadequacies in implemented systems. These inadequacies provide additional motivation for applying formal methods to the validation of electronic voting protocols. In this paper we report on some of our recent efforts in using the ap...

Privacy and verifiability refer to fundamental principles of democratic elections and therefore belong to the set of established security requirements which each electronic voting scheme is expected to meet. However, very different ideas and opinions about privacy and verifiability exist in the scientific community, which shows that both properties are not well understood yet. Moreover, althoug...

In this paper, we focus on verifiability of predicate encryption. A verifiable predicate encryption scheme guarantees that all legitimate receivers of a ciphertext will obtain the same message upon decryption. While verifiability of predicate encryption might be a desirable property by itself, we furthermore show that this property enables interesting applications. Specifically, we provide two ...

In a finitely repeated principal agent relationship with adverse selection I study (exogenous) interim information that is revealed during a long term relationship. Interim information mitigates adverse selection. Verifiability, measured by the cost of signal manipulation, and the signal’s informativeness determine the use and effectiveness of interim information: Less precise and more manipula...

Anonymity and verifiability are crucial security requirements for voting. Still, they seem to be contradictory, and confusion exists about their precise meanings and compatibility. In this paper, we resolve the confusion by showing that both can be expressed in terms of (un)linkability: while anonymity requires unlinkability of voter and vote, verifiability requires linkability of voters and el...

Dung’s abstract argumentation theory is a widely used formalism to model conflicting information and to draw conclusions in such situations. Hereby, the knowledge is represented by so-called argumentation frameworks (AFs) and the reasoning is done via semantics extracting acceptable sets. All reasonable semantics are based on the notion of conflict-freeness which means that arguments are only j...

We present a symbolic definition of election verifiability for electronic voting protocols. Our definition is given in terms of reachability assertions in the applied pi calculus and is amenable to automated reasoning using the tool ProVerif. The definition distinguishes three aspects of verifiability, which we call individual, universal, and eligibility verifiability. It also allows us to dete...