Fingercasting—Joint Fingerprinting and Decryption of Broadcast Messages
- Cite this paper as:
- Adelsbach A., Huber U., Sadeghi AR. (2006) Fingercasting—Joint Fingerprinting and Decryption of Broadcast Messages. In: Batten L.M., Safavi-Naini R. (eds) Information Security and Privacy. ACISP 2006. Lecture Notes in Computer Science, vol 4058. Springer, Berlin, Heidelberg
We propose a stream cipher that provides confidentiality, traceability and renewability in the context of broadcast encryption. We prove it to be as secure as the generic pseudo-random sequence on which it operates. This encryption scheme, termed fingercasting scheme, achieves joint decryption and fingerprinting of broadcast messages in such a way that an adversary cannot separate both operations or prevent them from happening simultaneously. The scheme is a combination of a broadcast encryption scheme, a fingerprinting scheme and an encryption scheme inspired by the Chameleon cipher. It is the first to provide a formal security proof and a non-constant lower bound for resistance against collusion of malicious users i.e., a minimum number of content copies needed to remove all fingerprints. The scheme is efficient and includes parameters that allow, for example, to trade-off storage size for computation cost at the receiving end.
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