Method and apparatus for combined encryption and scrambling of information on a shared medium network

A method for sequentially transmitting encrypted and scrambled information cells in a telecommunication system having a central office connected to a plurality of user premises networks via a shared medium network, the method comprising:

• generating a pseudo-random encryption pattern for a corresponding information cell;
• generating a scramble pattern;
• generating a pseudo-random sum pattern by modulo 2 addition of the pseudo-random encryption pattern and the scramble pattern;
• storing the pseudo-random sum pattern in a memory device;
• generating the encrypted and scrambled information cell by modulo 2 addition of the contents of the memory device and the information cell;
• and
• transmitting the encrypted and scrambled information cell with a preamble on the shared medium network.

A method of decrypting and descrambling information cells by a receiver in a telecommunication system having a central office connected to a plurality of receivers, each information cell being encrypted and scrambled and containing address information concerning a particular destination receiver which can properly decrypt and descramble the cell, the method comprising:

• generating a descramble and decryption sum pattern by modulo 2 addition of a descramble pattern and a decryption pattern;
• storing the descramble and decryption sum pattern in a memory device;
• comparing the address information of the cell and the receiver address;
• and
• generating the descrambled and decrypted cell by modulo 2 addition of the contents of the memory device and the received encrypted and scrambled cell if the address information matches.

A method of decrypting and descrambling information cells received by a receiver in an telecommunication system utilizing a shared medium network, the receiver having an address, each information cell being encrypted and scrambled, wherein each transmitted information cell has address information concerning a particular destination network termination which can properly decrypt and descramble the cell, the information cells being sequentially transmitted in a continuous information stream, the method comprising:

• generating a descramble and decryption sum pattern by modulo 2 addition of a descramble pattern and a decryption pattern;
• storing the descramble and decryption sum pattern in a memory device;
• sequentially extracting the encrypted and scrambled information cells from the information stream;
• and
• generating a processed cell by modulo 2 addition of the contents of the memory device and the extracted encrypted and scrambled cell;
• comparing the address information of the cell and the network termination address;
• and
• transferring the processed cell to the user premises network if the addresses match, wherein the processed cell is the decrypted and descrambled information cell when the addresses match.

An apparatus for transmitting an encrypted and scrambled information cell on a shared medium network comprising:

• a pseudo-random encryption pattern generator;
• a scramble pattern generator;
• a first modulo 2 adder having an output and two inputs, the inputs being connected to the pseudo-random encryption pattern generator and to the scramble pattern generator, wherein the first adder produces a pseudo-random sum pattern at its output;
• a second modulo 2 adder having an output and first and second inputs, the first input being connected to the output of the first adder and the second input for receiving an information cell that is to be transmitted, wherein the second adder produces the encrypted and scrambled information cell at its output;
• and
• a transmitter having and input connected to the output of the second adder and an output connected to the shared medium network for transmission of the encrypted and scrambled cell on the network.

An apparatus for decryption and descrambling of encrypted and scrambled information cells received from a shared medium network comprising:

• a descramble pattern generator;
• a decryption pattern generator;
• a first modulo 2 adder having two inputs and an output, the inputs being connected the descramble pattern generator and the decryption pattern generator;
• and
• a second modulo 2 adder having first and second inputs and an output, the first input being connected to the output of the first adder, the second input for receiving the encrypted and scrambled information cells transmitted on the network, and the output providing the descrambled and decrypted original information cell.

A method for a telecommunication system for the transmission of asynchronous transfer mode cells on a shared medium passive optical network having a line termination connected to a central office, and a plurality of network terminations connected to a like plurality of user premises networks, each network termination having an address and each asynchronous transfer mode cell having address information regarding an intended destination network termination, the method comprising:

• generating and transmitting an encrypted and scrambled asynchronous transfer mode cell by performing the steps of:
• generating offline a pseudo-random encryption pattern for a corresponding asynchronous transfer mode cell, and a scramble pattern,
• generating off line a pseudo-random sum pattern by adding modulo 2 the pseudo-random encryption pattern and the scramble pattern,
• storing the pseudo-random sum pattern in a memory device,
• generating the encrypted and scrambled asynchronous transfer mode cell by adding modulo 2 the contents of the memory device and the asynchronous transfer mode cell;
• and
• transmitting the encrypted and scrambled asynchronous transfer mode cell within an information stream on the passive optical network;
• and
• generating decrypted and descrambled asynchronous transfer mode cells from the information stream of the intended destination network termination by performing the steps of:
• generating a descramble and decryption sum pattern by modulo 2 addition of a descramble pattern and a decryption pattern;
• storing the descramble and decryption sum pattern in a memory device;
• sequentially extracting the encrypted and scrambled information cells from the information stream;
• and
• generating a processed cell by modulo 2 addition of the contents of the memory device and the extracted encrypted and scrambled cell;
• comparing the address information of the asynchronous transfer mode cell and the network termination;
• and
• transferring the processed cell to the user premises network if the addresses match, wherein when the addresses match the processed cell is the decrypted and descrambled original asynchronous transfer mode cell.