Abstract White-box implementation can ensure the security of cryptographic algorithm in white-box attack environment without changing the inputs and outputs of the original algorithm. Most existing white-box implementations construct a series of lookup tables to protect the key. However, with the development of white-box attack techniques, many white-box implementations have been proved to be insecure. In this paper, a new white-box implementation of SM4 is proposed, which is based on an equivalent partial SPN structure of the SM4 algorithm. Our implementation includes three types of table lookup operations and XOR operations. The round keys are obfuscated with the self-equivalences of the S-box and random affine encodings. Security analysis shows that our implementation can resist BGE-type attack, the attack based on affine equivalence algorithm, the structure attack, the collision attack and differential computational analysis. Furthermore, our scheme requires 8.125 MB of memory.

Abstract FOX block cipher was designed with a Lai–Massey scheme, in which the round function uses the Substitution-Permutation-Substitution structure. A meet-in-the-middle (MITM) attack is one of the most important issues for the security of the block cipher, which consists of a precomputation phase for constructing a distinguisher and an online phase for key recovery. This paper studies the MITM attacks against FOX. The first MITM distinguishers of 5-round FOX64, 7-round FOX64-256 and 5-round FOX128 are presented when using the differential enumeration technique with truncated differential characteristics. Then, based on these distinguishers, the attacks for key recovery on 7-round FOX64, 11-round FOX64-256 and 7-round FOX128 are presented with the state-test and state-search techniques. It is shown that the attack on 11-round FOX64-256 is proposed for the first time; attacks on 7-round FOX64 and 7-round FOX128 can be improved with lower time and memory complexities compared with the currently known attacks.

Abstract As an access control technology of digital material, digital rights management systems have a profound effect on the copyright protection of digital content. To address the threat of key exposure, applying white‐box ciphers is effective to provide a security guarantee for digital rights management systems. SPNbox, proposed at Asiacrypt’16 is such a white‐box cipher that fulfils comprehensive resistance against key exposure for digital rights management systems, including black‐box security on the server‐side and white‐box security on the client‐side. So far, the previous integral cryptanalysis of SPNbox employs a general 2‐round distinguisher without considering the details of SPNbox. The properties of SPNbox are carefully explored and a novel 2‐round integral distinguisher is introduced. On this basis, we propose new competitive 3‐round key recovery attacks with lower complexities. Particularly, the improved attack on 3‐round SPNbox‐32 only requires 2 32 chosen plaintexts, whereas the current best attack necessitates 2 62 chosen plaintexts. In addition, integral attacks on 4‐ and 5‐round SPNbox‐8 are presented for the first time. Thus, the security margin of SPNbox‐8 is narrowed by two rounds. These results indicate that the capability of SPNbox resisting integral cryptanalysis is inferior to the designers' claim.

Abstract Privacy‐preserving aggregation for smart grid communications, which precisely meets the requirement of periodically collecting users' electricity consumption while preserving privacy of each individual user, has been extensively studied in recent years. However, most of existing privacy‐preserving aggregation schemes are only focused on the summation aggregation. In this paper, based on the lattice cryptographic technique, we propose a novel privacy‐preserving dual‐functional aggregation scheme (PDA) for smart grid communications. With our proposed PDA scheme, each individual user just reports one data, then multiple statistic values, that is, mean and variance, of all users can be computed by the data & control center in the smart grid, while the privacy of each individual user can still be protected. Detailed security analyses demonstrate that our proposed PDA scheme is secure and robust. In addition, extensive performance evaluations also show that our proposed PDA scheme is efficient in terms of computational and communication overheads when the number of considered users is within an acceptable range. Copyright © 2015 John Wiley & Sons, Ltd.

As one of the next frontiers in wireless communications, Machine Type Communications not only support traditional short message service, but also provide multimedia services, such as voice and video services. The 3rd Generation Partnership Project has made a series of technical specifications of Multimedia Broadcast/Multicast Service for cellular network. However, they are inflexible for group key update, and will cause the core network over-burdened. Hence It is not suitable for Machine Type Communications, especially when mass MTC devices enjoy a specific Multimedia Broadcast/Multicast Service. A group key agreement in multimedia service for MTC communications is proposed to overcome the above disadvantages. The scheme could transmit group key information using broadcast messages and reduce the interacting rounds. Analysis of the scheme indicates that it is of backward and forward security and collusion resistance. In addition, the proposal could lower the communication costs to staying constant compared with that of MBMS.