Contributory broadcast encryption with efficient encryption and short ciphertexts

Identifier:  imarina:9052214

Handle: https://hdl.handle.net/20.500.11797/imarina9052214

Authors:  Qianhong Wu; Bo Qin; Lei Zhang; Josep Domingo-Ferrer; Oriol Farràs; Jesús A Manjón

Abstract:
Broadcast encryption (BE) schemes allow a sender to securely broadcast to any subset of members but require a trusted party to distribute decryption keys. Group key agreement (GKA) protocols enable a group of members to negotiate a common encryption key via open networks so that only the group members can decrypt the ciphertexts encrypted under the shared encryption key, but a sender cannot exclude any particular member from decrypting the ciphertexts. In this paper, we bridge these two notions with a hybrid primitive referred to as contributory broadcast encryption (ConBE). In this new primitive, a group of members negotiate a common public encryption key while each member holds a decryption key. A sender seeing the public group encryption key can limit the decryption to a subset of members of his choice. Following this model, we propose a ConBE scheme with short ciphertexts. The scheme is …