Look-up Table Based Fast Erasure Correction and Conditional Access Techniques for Streaming Media

In this paper, a new binary erasure correction algorithm for packet loss recovery and a packet oriented conditional access technique based on a novel stream cipher are proposed. Short-length binary linear block codes are used, with erasure correction based on two hard-decision decodings, look-up tables and simple logic for Hamming distance computation, comparison and selection between the two hard-decision decoder outputs. The proposed algorithm allows for high speed and low delay operation, making it ideal for streaming media applications over unreliable networks. Construction of the proposed stream cipher is based on employment of look-up table operations only, and their implementation within a tamper resistant ROM. The developed technique is a very fast one, suitable for real-time applications, and its cryptographic security is based on the intractability of the underlying algebraic problem. Common features of both techniques include their packet orientation (i.e., packet-by-packet processing) as well as their implementability based on a look-up table approach.