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].