In recent years more and more security sensitive applications use passive smart devices such as contactless smart cards and RFID tags. Cost constraints imply a small hardware footprint of all components of a smart device. One particular problem of all passive smart devices such as RFID tags and contactless smart cards are the harsh power constraints. On the other hand, active smart devices have to minimize energy consumption. Recently, many lightweight block ciphers have been published. In this paper we present three different architecture of the ultra-lightweight algorithm present and highlight their suitability for both active and passive smart devices. Our implementation results of the serialized architecture require only 1000 GE. To the best of our knowledge this is the smallest hardware implementation of a cryptographic algorithm with a moderate security level. 1 Background Smart cards are widely in use for authentication, access control, and payment purposes. Their applications r...