Device-to-device (D2D) communication is a direct means of communication between devices without an intermediate node, and it helps to expand cell coverage and to increase radio frequency reuse in a 5G network. Moreover, D2D communication is a core technology of 5G vehicle-to-everything (V2X) communication, which is an essential technology for autonomous driving. However, typical D2D communication in an 4G network which is typical telecommunication network has various security challenges including impersonation, eavesdropping, privacy sniffing, free-riding attack, etc. Moreover, when IoT technology emerges with 5G networks in massive machine type communication (mMTC) and ultra-reliable low latency communication (URLLC) application scenarios, these security challenges are more crucial and harder to mitigate because of the resource-constrained nature of IoT devices. To solve the security challenges in a 5G IoT environment, we need a lightweight and secure D2D communication system that can provide secure authentication, data confidentiality/integrity and anonymity. In this paper, we survey and analyze existing results about secure D2D communication systems in terms of their security considerations and limitations. Then, we lastly propose a secure D2D communication system to address the aforementioned security challenges and the limitations of the existing results. The proposed secure D2D communication was designed based on elliptic curve cryptography (ECC) and lightweight authenticated encryption with associated data (AEAD) ciphers to cover resource-constrained IoT devices.

The broadly configured smart city network requires a variety of security considerations for a heterogeneous device environment. Because a network of heterogeneous devices facilitates an attacker’s intrusion through a specific device or node, a device management framework is required to manage each node comprehensively. This paper proposes a blockchain-based device management framework for efficient device management, scalable firmware update and resiliences on attacks against smart city network. This framework offers four device management and firmware update mechanisms based on the performance and requirements of each device: bidirectional mechanism of general end node and a unidirectional mechanism of the lightweight end node. This difference optimizes the resource of network and devices in terms of management and security. All management history of each device is stored in the blockchain and transmitting firmware between vendor and management node is conducted through a smart contract of blockchain for security and resilience on the attack. Through the framework proposed in this paper, the confidentiality and availability of device management on smart city network as well as integrity, auditability, adaptability and authentication for each node are ensured and the effectiveness of the proposed framework is presented through the security analysis.

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The cube attack was proposed at the 2009 Eurocrypt. The attack derives linear polynomials for specific output bits of a BlackBox cipher. Cube attacks target recovery keys or secret states. In this paper, we present a cube attack on a 5-round Sycon permutation and a 6-round Sycon permutation with a 320-bit state, whose rate occupies 96 bits, and whose capacity is 224 bits. We found cube variables related to a superpoly with a secret state. Within the cube variables, we recovered 32 bits of the secret state. The target algorithm was Sycon with 5-round and 6-round versions of permutation. For the 5-round Sycon, we found a cube variable and recovered a state with a total of 2192 Sycon computations and 237 bits of memory. For the 6-round Sycon, we found cube variables and recovered a state with a total of 2192 Sycon computations and 270 bits of memory. When using brute force in a 5-round attack, 2224 operations were required, but the cube attack proposed in this paper had 248 offline operations, and 232 operations were required. When using brute force in a 6-round attack, 2224 operations were required, but the cube attack proposed in this paper required 295 offline operations, and 263 operations were required. For both attacks, offline could be used continuously after performing only once. To the best of our knowledge, this is the first cube attack on Sycon.