Efficient Identity-based Broadcast Encryption without Random Oracles

<p class="MsoNormal" style="margin: 0cm 0cm 0pt;"><span style="font-family: Times New Roman;"><span style="font-family: NimbusRomNo9L-Medi; font-size: 9pt; mso-bidi-font-family: NimbusRomNo9L-Medi;">We propose a new efficient identity-based broadcast encryption scheme without random oracles and prove that it achieves selective identity, chosen plaintext security. Our scheme is constructed based on bilinear Diffie-Hellman inversion assumption and it is a good efficient hybrid encryption scheme, which achieves </span><em><span style="font-family: CMMI9; font-size: 9pt; mso-bidi-font-family: CMMI9;">O</span></em><span style="font-family: CMR9; font-size: 9pt; mso-bidi-font-family: CMR9;">(1)</span><span style="font-family: NimbusRomNo9L-Medi; font-size: 9pt; mso-bidi-font-family: NimbusRomNo9L-Medi;">-size ciphertexts, public parameters and constant size private keys. In our scheme, either ciphertexts or public parameters has no relation with the number of receivers, moreover, both the encryption and decryption only require one pairing computation. Compared with other identity-based broadcast encryption schemes, our scheme has comparable properties, but with a better efficiency. </span></span><em><span style="font-family: NimbusRomNo9L-MediItal; font-size: 9pt; mso-bidi-font-family: NimbusRomNo9L-MediItal;"></span></em></p>