State convergence in bit-based stream ciphers
Sui-Guan Teo, Harry Bartlett, Ali Alhamdan, Leonie Ruth Simpson, Kenneth Koon‐Ho Wong, Ed Dawson · 2013
Well-designed initialisation and keystream generation processes for stream ciphers should ensure that each key-IV pair generates a distinct keystream. In this paper, we analyse some ciphers where this does not happen due to state convergence occurring either during initialisation, keystream generation or both. We show how state convergence occurs in each case and identify two mechanisms which can cause state convergence. 1