Practical Identity-Based Encryption (IBE) in Multiple PKG Environments and Its Applications

摘要

In this paper, we present a new identity-based encryption (IBE) scheme usingbilinear pairings. Our IBE scheme enjoys the same \textsf{Key Extraction} and\textsf{Decryption} algorithms with the famous IBE scheme of Boneh and Franklin(BF-IBE for short), while differs from the latter in that it has modified\textsf{Setup} and \textsf{Encryption} algorithms. Compared with BF-IBE, we show that ours are more practical in a multipleprivate key generator (PKG) environment, mainly due to that the session secret$g_{ID}$ could be pre-computed \emph{before} any interaction, and the sendercould encrypt a message using $g_{ID}$ prior to negotiating with the intendedrecipient(s). As an application of our IBE scheme, we also derive an escrowedElGamal scheme which possesses certain good properties in practice.