**Secure Identity-based
Encryption in the Quantum Random Oracle Model**

Mark Zhandry (

**Abstract:**

We give the first proof of security for an identity-based encryption scheme
in the quantum random oracle model. This is the first proof of security for
any scheme in this model that requires no additional assumptions. Our
techniques are quite general and we use them to obtain security proofs for
two random oracle hierarchical identity-based encryption schemes and a random
oracle signature scheme, all of which have previously resisted quantum
security proofs, even using additional assumptions. We also explain how to
remove the extra assumptions from prior quantum random oracle model proofs.
We accomplish these results by developing new tools for arguing that quantum
algorithms cannot distinguish between two oracle distributions. Using a particular
class of oracle distributions, so called semi-constant distributions, we
argue that the aforementioned cryptosystems are secure against quantum
adversaries.