Cryptanalysis of RAKAPOSHI Stream Cipher
Stream ciphers are symmetric encryption algorithms based on the concept of pseudorandom key-stream generator. Although it seems rather difficult to construct a very fast and secure stream cipher, some efforts to achieve this have recently been deployed. The NESSIE project launched in 1999 by the European Union did not succeed in selecting a secure enough stream cipher. RAKAPOSHI is a hardware oriented stream cipher designed by Carlos Cid et al. in 2009. The stream cipher is based on Dynamic Linear Feedback Shift Registers, with a simple and potentially scalable design, and is particularly suitable for hardware applications with restricted resources. The RAKAPOSHI stream cipher offers 128-bit security. In this paper, the authors point out some weaknesses in the cipher.