MDMR-IBE: Efficient multiple domain multi-receiver identity-based encryption

In The International Conference on Practice and Theory in Public-Key Cryptography (PKC)'05, Baek et al. proposed the first multi-receiver identity-based encryption scheme. Their scheme is highly efficient in that it only needs one pairing computation to encrypt a single message for n receivers. However, the application scenario considered by Baek et al. is merely the ideal "single domain environment," where all the n receivers are from the same administrative domain. When used in the real-world application scenario where the n receivers are from l different administrative domains (i.e., a multiple domain environment), their scheme becomes inefficient as it requires l pairing computations for one message. In this paper, we present an efficient multiple domain multi-receiver identity-based encryption scheme that only requires "one" pairing computation to encrypt a single message for n receivers from l different administrative domains. We prove the security of the new scheme under the modified decisional bilinear Diffie-Hellman assumption in the random oracle model. In addition, the new scheme can be extended to be adaptive chosen ciphertext secure under the gap modified bilinear Diffie-Hellman assumption.