Efficient and Fully Secure Lattice-Based IBE with Equality Test

Identity-based encryption with equality test (IBEET), derived from public key encryption with equality test (PKEET), allows the equality test algorithm on two ciphertexts without decrypting the messages and simplifies the certificate management of PKEET. In response to the explosive growth of quantum computing, recently, some IBEET schemes based on the learning with errors (LWE) problem were proposed, which could survive under the quantum attacks. However, there are several unsatisfactory performances on either efficiency or security due to the key size and the security loss. In this work, we construct an efficient and fully secure IBEET scheme from the LWE problem in the standard model. Our construction favors weakly compact key size, which refers that our key size is independent of the bit length of identity l and only depends on a smaller value (i.e., the seed length lambda of pseudorandom function (PRF)). Moreover, we achieve full security in the standard model without abort-resistant hash functions in security proof compared with prior adaptively secure lattice-based IBEET schemes, which reduces the losses of efficiency and security.