Incremental symmetric puncturable encryption with support for unbounded number of punctures.

Puncturable encryption allows recipients to revoke the decryption capability of ciphertexts flexibly, thus provides a fine-grained way to achieve forward security. So far, puncturable encryption and its variants have found many interesting applications, including the design of advanced cryptographic protocols and messaging systems. In this paper, we put forward the first generic construction of incremental symmetric puncturable encryption that can support an arbitrary number of punctures and achieve semantic security without random oracles. To this end, we introduce the notion of extended key-homomorphic puncturable PRF (EKHP-PRF) by abstracting the properties implicitly desired in many applications of almost key-homomorphic PRFs, which essentially removes the influence of errors due to almost key-homomorphism. Moreover, we present an efficient instantiation of EKHP-PRF based on a variant of Module Learning with Errors (MLWE) problem, namely non-uniform MLWE (NMLWE). Thus, we get the first lattice-based puncturable encryption featuring an arbitrary number of punctures in the standard model. [ABSTRACT FROM AUTHOR]