An encryption scheme for high speed passive optical networks

The prohibitive cost of dedicated fiber local loops for residential customers led to the development of passive optical networks (PONs) for access to broadband services. However the passive splitting of optical signals which gives flexibility, low cost and robustness creates a broadcast physical topology compromising customer privacy. Encryption is the only cost-effective way to prohibit global reception and create the required point-to point logical links restoring confidentiality to the desirable degree. Because of the very high speed of such networks, only solutions amenable to hardware implementations are acceptable. ATM cells are allocated to the system users on a time division basis each encrypted with a different key. A suitable for the PON environment encryption solution based on the summation generator stream cipher is presented with an outline of its hardware implementation.