Packet switching architecture providing encryption across packets

Apparatus for the prevention of unauthorized detection of the start and end of packets and for use with trunk controllers of packet switching networks that are formed into a packet switching system by interconnecting said trunk controllers of each switching network by trnks* to other trunk controllers of other packet switching networks, wherein in a first one of said trunk controller is communicating packets to a second one of said trunk controller via a first one of said trunks, said apparatus comprising:

• a plurality of means for encrypting each connected to an individual trunk controller and connected to an individual trunk;
• a plurality of means for decrypting each connected to an individual trunk controller and connected to an individual trunk;
• each one of said plurality of encrypting means comprises means for preparing packets for transmission from internal generated packets or packets received from the connected trunk controller;
• means for random generating a flag corresponding to each of the packets to be transmitted on the connected trunk controller thereby encrypting the generated flag;
• means for aliasing the data of each packet received from said preparing means with the corresponding flag received from said random generating means;
• means for each packet for first selecting the corresponding flag and then the packet for transmission on the connected trunk;
• and
• each of said plurality of means for decrypting comprises means responsive to the receipt of a flag and packet from the connected trunk for generating a flag corresponding to the received flag by maintaining synchronization with the flags being received from the connected trunk to identify the start of the received packet;
• means responsive to the generated flag and the received packet for unaliasing the flag from the data of the packet;
• means for receiving the the unaliasing data of each packet to transfer said unaliased data to the connected trunk controller;
• said generating means of said one of said plurality of decrypting means connected to said second one of said trunk controllers comprises means for detecting the lack of correspondence between said generated flags and said received flags;
• means for transmitting a first reset signal to said preparing means of said one of said plurality of encrypting means said second one of said trunk controllers upon detection of said lack of correspondence;
• said preparing means of said one of said plurality of encrypting means of said second one of said trunk controllers comprise means for assembling a reset packet for transmission to said first one of said trunk controllers via said aliasing means and said selecting means of said one of said plurality of encrypting means of said second one of said trunk controllers and said first one of said trunks;
• said generating means of said one of said plurality of decrypting means of said second one of said trunk controllers comprise means responsive to said lack of correspondence for initializing said generating means to generate an initial flag pattern upon receipt of said reset packet from said first one of said trunks;
• said receiving means of said one of said plurality of decrypting means of said first one of said trunk controllers comprise means responsive to said reset packet for generating a second reset signal;
• and
• said random generating means of said one of said plurality of encrypting means of said first one of said trunk controllers comprises means responsive to said second reset signal for initializing said random generating means to generate said initial flag pattern thereby regaining synchronization with said one of said plurality of decrypting means of said second one of said trunk controllers.

A method for preventing the unauthorized detection of the start and end of packets being transmitted in a packet switching system for transmission of packets and flags to separate said packets during transmission with said packet switching system having packet switching networks including communication controllers and said packet switching networks being interconnected by communication paths between said networks and each end of said communications paths terminates on an individual one of said communication controllers, said method comprising the steps of:

• only encrypting flags separating packets upon transmission of said packets;
• and said flags;
• and
• decrypting said encrypted flags upon receipt of said packets and said flags.