In this paper we discuss an efficient implementation for selective disclosure of attribute-based credentials on smart cards. In this context we concentrate on the implementation of this core feature of IBM's Identity Mixer (Idemix) technology. Using the MULTOS platform we are the first to provide this feature on a smart card. We compare Idemix with Microsoft's U-Prove technology, as the latter also offers selective disclosure of attributes and has been implemented on a smart card [10].

Summary. In this paper we discuss an efficient implementation of anonymous credentials on smart cards. In general, privacy-preserving protocols are computationally intensive and require the use of advanced cryptography. Implementing such protocols for smart cards involves a trade-off between the requirements of the protocol and the capabilities of the smart card. In this context we concentrate on the implementation of Microsoft's U-Prove technology on the MULTOS smart card platform. Our implementation aims at making the smart card independent of any other resources, either computational or storage. In contrast, Microsoft suggests an alternative approach based on device-protected tokens which only uses the smart card as a security add-on. Given our very good performance results we argue that our approach should be considered in favour of Microsoft's one. Furthermore we provide a brief comparison between Java Card and MULTOS which illustrates our choice to implement this technology on the latter more flexible and low-level platform rather than the former.

Abstract. This paper describes an elementary protocol to prove possession of anonymous credentials together with its implementation on smart cards. The protocol uses self-blindable attribute certificates represented as points on an elliptic curve (which are stored on the card). These certificates are verified on the reader-side via a bilinear pairing.Java Card smart cards offer only very limited access to the cryptographic coprocessor. It thus requires some ingenuity to get the protocol running with reasonable speed. We realise protocol runs with on-card computation times in the order of 1.5 seconds. It should be possible to further reduce this time with extended access to the cryptographic coprocessor.

Abstract. We present a formal model for stateful security protocols. This model is used to define ownership and ownership transfer as concepts as well as security properties. These definitions are based on an intuitive notion of ownership related to physical ownership. They are aimed at RFID systems, but should be applicable to any scenario sharing the same intuition of ownership. We discuss the connection between ownership and the notion of desynchronization resistance and give the first formal definition of the latter. We apply our definitions to existing RFID protocols, exhibiting attacks on desynchronization resistance, secure ownership, and secure ownership transfer.