International Association
for Cryptologic Research

We construct an identity-based encryption (IBE) scheme from the standard Learning with Errors (LWE) assumption, which both has a \emph{compact} public-key (with size similar to known lattice-based PKE schemes) and also achieves \emph{adaptive} security in the standard model. This improves over previous IBE schemes from lattices, which either have a public key that grows at least linearly with the length of the supported identities, or achieve a non-adaptive notion of security, or require a random oracle.

Additionally, our techniques from IBE can be adapted to construct a compact digital signature scheme, which achieves existential unforgeability under the standard Short Integer Solution (SIS) assumption with small polynomial parameters.