Improvement of Chang-Wu broadcasting cryptosystem using geometric properties of lines

In 1991, Chang and Wu proposed a broadcasting cryptosystem using interpolating polynomials and geometric properties of circles. The Chang-Wu scheme can be further enforced by using a time-variant parameter and a one-way function to protect legal receivers´ secrets from being disclosed. The authors present an improvement of the Chang-Wu scheme using geometric properties of lines. This improvement repairs the security flaws inherent in the original Chang-Wu scheme, while requiring fewer public parameters and less computing time