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.
Recently, Boneh et al. REF have presented a fully-collusion resistant traitor tracing scheme which has private keys of constant size and ciphertexts of size O( √ ).
Fully collusion resistant traitor tracing with short ciphertexts and private keys
In Eurocrypt ’06
Computer Science