Contributory Broadcast Encryption with Efficient Encryption and Short Cipher texts
Contributory Broadcast Encryption with Efficient Encryption and Short Cipher texts,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.
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In this Contributory Broadcast Encryption with Efficient Encryption and Short Cipher texts paper, we formalized the ConBE primitive. In ConBE, anyone can send secret messages to any subset of the group members, and the system does not require a trusted key server. Neither the change of the sender nor the dynamic choice of the intended receivers require extra rounds to negotiate group encryption/decryption keys. Following the ConBE model, we instantiated an efficient ConBE scheme that is secure in the standard model. As a versatile cryptographic primitive, our novel ConBE notion opens a new avenue to establish secure broadcast channels and can be expected to se-cure numerous emerging distributed computation applications.