Optimizing ring signature keys for e-voting

The development of novel multiple signature methods has spurred the emergence of many new security services in digital communications. One of these services is anonymity, that has been used, among many other things, in electronic voting. Thus, as new cryptographic operators have appeared, the older ones have become more specialized. In turn, this has given rise to a need for keys with very specific arithmetic properties, as well as a very specific management. In this paper we address one such instance. Our goal will be to offer a portable identification (login / password) system that will give access to the cryptographic keys actually used in the voting protocol. This way, the user will be able to use the protocol with full guarantees. In our chosen electronic voting protocol, anonymity is achieved by means of spontaneous ring signatures that use cryptographic accumulators and that, while able to issue constant size signatures, are of dubious computational efficiency. In order to attain this goal, we propose the creation, in a computationally optimal way, of a cryptographically secure key store to be used for the voting protocol. The voter will acquire a set of keys with the guarantee that the store will be unable to know which set the user gets. As for the store, it will have proof that the voter has taken one and only one set. When implementing the store we will restrict the key search to the algebraic sets imposed by the requirements of the cryptographically accumulator we will be using.