Group Signatures on Mobile Devices: Practical Experiences

Group signature schemes enable participants to sign on behalf of a group in an anonymous manner. The upcoming ISO20008-2 standard defines seven such schemes, which differ in terms of capabilities, used crypto systems and revocation approaches. Further information about practical considerations, such as runtime performance or implementation overhead is considered useful when deciding for a certain scheme. We present a Java framework that allows for a detailed comparison of the mechanisms, of which three are already implemented. For these implemented mechanisms, a detailed performance evaluation is shown
for both a notebook and Android-based mobile devices. Furthermore, significant experiences during implementing and evaluating the schemes as well as crucial bottlenecks are pointed out. We remain in the flexible Java environment, without special platform-specific optimizations. Using precomputation, we already achieve acceptable online signing timings. Signing times are considered most important given proposed application scenarios.