Analysis of a Key Distribution Scheme in Secure Multicasting
This work addresses security flaws in multicasting key distribution, providing incremental improvements in attack efficiency for cryptographers and system designers.
The paper analyzes a secure key broadcasting scheme by Wu et al., identifying vulnerabilities through two attacks, including a time-memory tradeoff that can break over one-third of cases with complexity reduced to the square root of previous attacks.
This article presents an analysis of the secure key broadcasting scheme proposed by Wu, Ruan, Lai and Tseng. The study of the parameters of the system is based on a connection with a special type of symmetric equations over finite fields. We present two different attacks against the system, whose efficiency depends on the choice of the parameters. In particular, a time-memory tradeoff attack is described, effective when a parameter of the scheme is chosen without care. In such a situation, more than one third of the cases can be broken with a time and space complexity in the range of the square root of the complexity of the best attack suggested by Wu et al. against their system. This leads to a feasible attack in a realistic scenario.