Cloning and Optimal Gaussian individual attacks for continuous-variable   quantum key distribution using coherent states and reverse reconciliation
  We investigate the security of continuous-variable (CV) quantum key distribution (QKD) using coherent states and reverse reconciliation against Gaussian individual attacks based on an optimal Gaussian $1 \to 2$ cloning machine. We provide an implementation of the optimal Gaussian individual attack. we also find a Bell-measurement attack which works without delayed choice of measurements and has better performance than the cloning attack. 
Ryo Namiki, Masato Koashi, Nobuyuki Imoto