# DCAGS-IoT: Dynamic Cross-Domain Authentication Scheme Using Group Signature in IoT
## 2 Related Work  
A cross-domain authentication protocol in the IoT environment has been proposed by researchers for a long time. However, most of the traditional schemes are PKI-based and IBC-based. [PERSON] et al. [5] proposed combining threshold secret sharing and identity-based encryption to construct a certificate authority domain that minimizes the length of the verification path and improves the authentication efficiency. Aiming at the large computational cost of the bilinear pairing operation in the elliptic curve and the certificate management in the PKI, [PERSON] et al. [6] designed a efficient and secure authenticated key agreement protocol based on the identity-based public key cryptography algorithm and the GDH difficulty problem on the elliptic curve addition group. [PERSON] et al. [7]also proposed a new bilinear-free, IBC-based two-party cross-domain authenticated key agreement protocol. Devices have higher requirements for the versatility of cross-domain authentication systems between different cryptosystems. [PERSON] et al. [8] proposed a complete cross-domain authentication scheme that could be used by participants in different domains with completely different settings, and the underlying design of the scheme was based on blockchain technology. [PERSON] et al. [9] proposed a cross-domain identity authentication scheme based on PKI and certificateless cryptography (CLC) to achieve mutual identity authentication and secure access between users of the two public key cryptosystems. [PERSON] et al. [10] proposed a secure and effective fog computing key negotiation and user authentication scheme that could establish secure sessions between different entities, and users could achieve cross-domain access to other fog servers. [PERSON] et al. [11] proposed a proxy-blind signature-based approach for cross-domain identity authentication schemes based on public key infrastructures of different systems and certificateless public key cryptosystems that could not satisfy identity blindness and efficient heterogeneous cross-domain authentication. [PERSON] et al. [12] combined blockchain technology with an identity-based cryptographic system to provide a cross-domain authentication scheme that solves the problem of devices in trust domains with different authentication mechanisms when cooperating with each other. These centralized cross-domain authentication protocols usually require a lot of computing or communication resources and have problems such as relying on trusted third parties to issue certificates and key escrow. The core advantage of blockchain decentralization has promoted the development of the field of identity authentication. Therefore, in order to solve the above problems, there are many solutions that use blockchain technology to improve them. [PERSON] et al. [13] designed a new blockchain-based batch authentication scheme in IoV-based smart city deployments that enabled vehicle-to-vehicle (V2V) authentication and allowed a group of clustered vehicles to authenticate through it. [PERSON] et al. [14] proposed a blockchain-based decentralized trust management system where the RSUs at the edge cooperatively maintain updated, reliable, and consistent vehicle trust values to reduce the workload from the master-maintained blockchain. However, due to the fact that wireless communication channels may be destroyed and taken over by malicious adversaries, and the open and transparent characteristics of blockchain, data in transit may be eavesdropped, modified, and replayed. Protecting user privacy and secure authentication are important prerequisites for ensuring secure communication as well as an important requirement for dynamic cross-domain authentication. [PERSON] et al. [15] proposed a certificate-free CPPA protocol to support privacy and security requirements in IoV systems where the vehicle and trusted authority (TA) do not need to store any certificates separately for verification and tracking. [PERSON] et al.