Statistical Study On The Number Of Injective Linear Finite Transducers
  The notion of linear finite transducer (LFT) plays a crucial role in some cryptographic systems. In this paper we present a way to get an approximate value, by random sampling, for the number of non-equivalent injective LFTs. By introducing a recurrence relation to count canonical LFTs, we show how to estimate the percentage of $\tau$-injective LFTs. Several experimental results are presented, which by themselves constitute an important step towards the evaluation of the key space of those systems. 
Ivone Amorim, Ant\'onio Machiavelo, Rog\'erio Reis
cs.FL