On the correction of errors in quantum cryptography systems

Key generation in a two-pass quantum cryptography system involving protocols on geometrically uniform coherent states is studied. Results on the correction of errors in this system without opening a part of the raw key to estimate the probability of errors but involving the monitoring of the parameters of the system and the quantum communication channel sufficient for an a priori estimate of the probability of errors, which is used to choose a correcting code, are reported.