Secure many-to-one symbol transmission for implementation on smart cards

Multicast communication is arguably the most promising paradigm to enable mass Internet transmission of live events, or any other content sent on the network from a single source to a large community of receivers. A tree model is normally used to represent this type of communication. Scalability problems arise when communication is many-to-one (leaf-to-root) rather than one-to-many (root-to-leaf): this is the case when the root collects data (sensor information, usage data, micropayments in real-time pay-per-view, etc.) from the leaves. The matter is further complicated if there are confidentiality and authenticity requirements on the leaf-to-root traffic. We present here a new method offering security and scalability in many-to-one communication which outperforms previous proposals in the literature: it is more general, it saves more bandwidth and it is computationally simpler. In particular, computation at the leaves is simple enough to be encapsulated in a smart card, which is attractive to protect the key material held by the leaves.