Abstract. We construct a fully collusion resistant tracing traitors system with sublinear size ciphertexts and constant size private keys. More precisely, let N be the total number of users. Our system generates ciphertexts of size O( √ N ) and private keys of size O(1). We first introduce a simpler primitive we call private linear broadcast encryption (PLBE) and show that any PLBE gives a tracing traitors system with the same parameters. We then show how to build a PLBE system with O( √ N ) size ciphertexts. Our system uses bilinear maps in groups of composite order.
Boneh, Sahai and Waters REF extended this notion to construct private linear broadcast encryption and proposed a fully collusion resistant tracing traitors scheme with sublinear size ciphertexts and constant size private keys.
Fully collusion resistant traitor tracing with short ciphertexts and private keys
In Eurocrypt ’06
Computer Science