  Quantum cryptography leverages many unique features of quantum information in
order to construct cryptographic primitives that are oftentimes impossible
classically. In this work, we build on the no-cloning principle of quantum
mechanics and design cryptographic schemes with key-revocation capabilities. We
consider schemes where secret keys are represented as quantum states with the
guarantee that, once the secret key is successfully revoked from a user, they
no longer have the ability to perform the same functionality as before. We
define and construct several fundamental cryptographic primitives with
key-revocation capabilities, namely pseudorandom functions, secret-key and
public-key encryption, and even fully homomorphic encryption, assuming the
quantum subexponential hardness of the learning with errors problem. Central to
all our constructions is our approach for making the Dual-Regev encryption
scheme (Gentry, Peikert and Vaikuntanathan, STOC 2008) revocable.
