Abstract Attribute‐based encryption (ABE) is a promising management method that enables fine‐grained access control in large‐scale systems. Revocable ABE (RABE) can support a key revocation mechanism in an ABE system. With the advent of the Internet of Things, users may need to delegate their decryption capacity to other devices, which requires that RABE meet a necessary feature called decryption key exposure resistance (DKER). Although many constructions about RABE from bilinear maps have been proposed, the situation of lattice‐based constructions with DKER is less satisfactory. In order to narrow this gap, this paper propose the first lattice‐based RABE with DKER. First, a formal description of RABE with DKER and the corresponding security models is proposed. Subsequently, a lattice‐based RABE scheme without DKER is constructed and it is proved to be selective indistinguishability under chosen‐plaintext attack (IND‐CPA) security based on Learning with Errors (LWE). To achieve DKER, this paper construct a RABE scheme by using the RABE scheme without DKER and a key extension mechanism as its building blocks. Finally, this paper show that this scheme is selective IND‐CPA security, with the DKER based on LWE.

Abstract Aigis‐Enc is an encryption algorithm based on asymmetrical learning with errors (LWE). A thorough comparison between Aigis‐Enc (with the recommended parameters) and a symmetrical LWE encryption scheme on the same scale (the sampling parameters are { η 1 , η 2 } = {2, 2} instead of {1, 4}) on Chosen‐plaintext attack (CPA) security, computation complexity and decryption failure probability is made. In particular, the authors ascertain that the CPA security of Aigis‐Enc is 160.895, and that of the symmetrical LWE encryption scheme on the same scale is 161.834. The ratio of computation complexity on the sampling amount of the former and the latter is 5:4 in the key generation phase and 19:14 in the encryption phase. The decryption failure probability of the former is 2 −128.699 and that of the latter is 2 −67.0582 , then the authors show how to reduce the decryption failure probability of the latter significantly by increasing some traffic. Furthermore, those attacks presented by designers of Aigis‐Enc, including primal attacks and dual attacks are generalised. Our attacks are more extensive, simpler, and clearer. With them, the optimal attacks and the ‘optimal‐optimal attacks’ on Aigis‐Enc and the symmetrical LWE scheme on the same scale are obtained.

Attribute-based encryption (ABE) can support a fine-grained access control to encrypted data. When the user’s secret-key is compromised, the ABE system has to revoke its decryption privileges to prevent the leakage of encrypted data. Although there are many constructions about revocable ABE from bilinear maps, the situation with lattice-based constructions is less satisfactory, and a few efforts were made to close this gap. In this work, we propose the first lattice-based server-aided revocable attribute-based encryption (SR-ABE) scheme and thus the first such construction that is believed to be quantum resistant. In the standard model, our scheme is proved to be secure based on the hardness of the Learning With Errors (LWE) problem.