We present the design of a secure and privacy preserving e-petition system that we have implemented as a proof-of-concept demonstrator. We use the Belgian e-ID card as source of authentication, and then proceed to issue an anonymous credential that is used to sign petitions. Our system ensures that duplicate signatures are detectable, while preserving the anonymity of petition signers. We analyze the privacy and security requirements of our application, present an overview of its architecture, and discuss the applicability of data (...) protection legislation to our system. (shrink)