Date Added: May 2010
The authors present a technique for delegating a short lattice basis that has the advantage of keeping the lattice dimension unchanged upon delegation. Building on this result, they construct two new Hierarchical Identity-Based Encryption (HIBE) schemes, with and without random oracles. The resulting systems are very different from earlier lattice-based HIBEs and in some cases result in shorter cipher-texts and private keys. They prove security from classic lattice hardness assumptions. Hierarchical Identity Based Encryption (HIBE) is a public key encryption scheme where entities are arranged in a directed tree.