(Hierarchical) Identity-Based Encryption from Affine Message Authentication

In this talk, we provide a generic transformation from any affine message authentication code (MAC) to an identity-based encryption (IBE) scheme over pairing groups of prime order. If the MAC satisfies a security notion related to unforgeability against chosen-message attacks and, for example, the k-Linear assumption holds, then the resulting IBE scheme is adaptively secure. Our security reduction is tightness preserving, i.e., if the MAC has a tight security reduction so has the IBE scheme. Furthermore, the transformation also extends to hierarchical identity-based encryption (HIBE). We also show how to construct affine MACs with a tight security reduction to standard assumptions. This is a joint work with Olivier Blazy and Eike Kiltz, and is published at CRYPTO 2014. An extended version is available at http://eprint.iacr.org/2014/581