Identity-Based Encryption from Lattices with Small Cipher Size

Identity-based encryption (IBE) is very attractive because it does not have certificate management issues. However, the IBEs based on the bilinear Diffie-Hellman problem cannot resist quantum attacks. In order to ensure security under quantum attacks, lattice-based IBE is proposed. However, the existing lattice-based IBEs usually not only have a large ciphertext size but also can only encrypt a few bits of plaintext information in one ciphertext. In this paper, we propose a new lattice-based IBE scheme based on learning with errors (LWE) and its ring version. For the setting l=n , our scheme can encrypt the plaintext twice long of other schemes in one ciphertext. Then we prove that our scheme can achieve the indistinguishability of ciphertexts against adaptively chosen identity and chosen plaintext attack (IND-ID-CPA) in the random oracle.