公开(公告)号：US4953211A

公开(公告)日：1990-08-28

申请号：US375575

申请日：1989-07-05

申请人： Andrew S. Repton ,  Martin Lysejko

发明人： Andrew S. Repton ,  Martin Lysejko

IPC分类号： G06F7/58 ,  G09C1/10 ,  H04K1/04 ,  H04K1/06

CPC分类号： H04K1/06

摘要： Encryption apparatus mainly intended for encrypting speech signals samples a signal to be encrypted at two differing rates, and reads the sampled signal into storage means at one of said rates and reads it out of said storage at the other of said rates so that the signal is alternately dispersed upwardly and downwardly with each pair of upward and downward dispersion representing a frame. To improve security the apparatus further generates a pseudo random binary number, defines a superframe structure consisting of a predetermined number of said frames, and sets the starting point of each individual superframe as an upward or a downward dispersion in dependence on the next digit of said pseudo-random binary number.