A Novel Contributory Broadcast Encryption Framework with Short Cipher texts and Efficient Key Negotiation
Author
Ch Kavya, A Sathvika, Budde Rohini, B Neelima
Abstract
Traditional broadcast encryption (BE) schemes enable a sender to broadcast encrypted data securely to any dynamic subset of receivers but rely heavily on a centralized trusted authority to generate and distribute decryption keys. Conversely, group key agreement (GKA) protocols allow members to establish a shared key over public channels, but fail to support sender-driven dynamic exclusion of specific members. To overcome these limitations, this paper investigates a hybrid cryptographic primitive termed Contributory Broadcast Encryption (ConBE). Under ConBE, group members collaboratively negotiate a common public encryption key while independently maintaining unique private decryption keys. Any sender possessing the group public key can unilaterally encrypt messages to an arbitrary subset of members without re-running key agreement rounds. We construct an efficient ConBE scheme utilizing an Aggregatable Broadcast Encryption (AggBE) building block. The proposed framework guarantees full collusion resistance under the decision n-Bilinear Diffie-Hellman Exponentiation (n-BDHE) assumption in the standard model. Our scheme achieves constant-size ciphertexts, low online computational overhead, and single-round setup negotiation. Experimental evaluation and theoretical analysis demonstrate the feasibility and superior scalability of the framework for dynamic distributed environments.
Keywords
Broadcast Encryption, Group Key Agreement, Contributory Broadcast Encryption, Aggregatable Broadcast Encryption, Constant-Size Ciphertext, Bilinear Diffie-Hellman, Collusion Resistance, Network Security.
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References
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