System and method for securing a communication channel over an optical network

A method for securing a communications channel having perfect forward secrecy comprising the steps of:

• receiving an authorization response message comprising an encrypted first asymmetric key exchange parameter;
• in response to receiving the authorization response message, decrypting the encrypted asymmetric key exchange parameter;
• selecting a secret key parameter;
• and
• calculating a second asymmetric key exchange parameter based on the secret key parameter;
• and
• calculating a shared asymmetric encryption key based on the secret key parameter and the first asymmetric key exchange parameter.

A method for generating non-linear ciphertext derived from a linear source comprising the steps of:

• selecting a first tap and a second tap in a register;
• combining an output of the first tap with an output of the second tap;
• calculating a first value from a logical “and” operation taken between the outputs of the first and second taps;
• selecting a third output bit of the register;
• combining the first value with the third output bit of the register;
• calculating a second value from an exclusive “or” operation taken between the first value and the least significant output bit of the register;
• and
• forming ciphertext derived from plain text and the second value.

A laser transceiver node comprising:

• an optical tap routing device for apportioning the bandwidth between subscribers of an optical network system, the optical tap routing device further operable for:
• selecting a symmetric key parameter;
• calculating a key exchange parameter based on the symmetric key parameter;
• encrypting the key exchange parameter with the symmetric key;
• a tap multiplexer coupled to the optical tap routing device for multiplexing upstream and downstream signals.

A subscriber optical interface comprising:

• a processor for controlling the digital optical transmitter and receiver, the processor further operable for:
• receiving a message comprising an encrypted first asymmetric key exchange parameter;
• in response to receiving the message, decrypting the encrypted asymmetric key exchange parameter;
• selecting a secret key parameter;
• and
• calculating a second asymmetric key exchange parameter based on the secret key parameter.

A system for securing communications channels, comprising:

• a register comprising;
• a first tap and a second tap for calculating a first value taken between the outputs of the first and second taps, the output between the first tap and second tap comprising a non-linear value;
• an output of the register taken between the first value and a third output bit of the register;
• and
• a new bit comprising an operation taken between the taps of the register.