New Anonymity Notions for Identity-Based Encryption

Abstract : Identity-based encryption is a very convenient tool to avoid key management. Recipient-privacy is also a major concern nowadays. To combine both, anonymous identity-based encryption has been proposed. This paper extends this notion to stronger adversaries (the authority itself). We discuss this new notion, together with a new kind of non-malleability with respect to the identity, for several existing schemes. Inter- estingly enough, such a new anonymity property has an independent application to password-authenticated key exchange. We thus come up with a new generic framework for password-authenticated key exchange, and a concrete construction based on pairings.