How to Construct Multicast Cryptosystems Provably Secure Against Adaptive Chosen Ciphertext Attack

* Final gross prices may vary according to local VAT.

Get Access

Abstract

In this paper we present a general framework for constructing efficient multicast cryptosystems with provable security and show that a line of previous work on multicast encryption are all special cases of this general approach. We provide new methods for building such cryptosystems with various levels of security (e.g., IND-CPA, IND-CCA2). The results we obtained enable the construction of a whole class of new multicast schemes with guaranteed security using a broader range of common primitives such as OAEP. Moreover, we show that multicast cryptosystems with high level of security (e.g. IND-CCA2) can be based upon public key cryptosystems with weaker (e.g. CPA) security as long as the decryption can be securely and efficiently “shared”. Our constructions feature truly constant-size decryption keys whereas the lengths of both the encryption key and ciphertext are independent of group size.

This work was supported by National Science Foundation award #EIA-0122599 (Title: “ITR/SI: Societal Scale Information Systems: Technologies, Design, and Applications”).