In response to the call for candidates issued by the National Institute for Standards and Technologies (the Advanced Encryption Standard project) the Ecole Normale Superieure proposed a candidate called DFC (Decorrelated Fast Cipher). DFC is based on a decorrelation technique that provides provable security against several classes of attacks (in particular the basic version of E. Biham and A. Shamir's (1993) Differential Cryptanalysis as well as M. Matsui's (1994) Linear Cryptanalysis). From a practical point of view, this algorithm is naturally very efficient when it is implemented on 64-bit processors. The authors describe the implementation of DFC on a very low cost smart card based on the Motorola 6805 processor. The performances obtained prove that DFC is also well suited for low cost device applications