# Blockchain-Enabled Secure and Interoperable Authentication Scheme for Metaverse Environments
## 4 System Model  
The proposed secure and interoperable authentication scheme using blockchain is shown in Figure 1. It demonstrates how Meta-ID will create an interoperable authentication possible and, at the same time, will ensure security across metaverse environments. The system model comprises the following components:  
Figure 1: Proposed system model. * Blockchain: In our system model, we have proposed the use of an enterprise blockchain platform--Hyperledger Fabric. This blockchain platform makes the identity mechanism completely decentralized. All devices, users, and avatars are registered on blockchain and are each assigned a unique ID called Meta-ID. Hyperledger Fabric helps in storing the authentication information securely. The blockchain is not owned by any single entity, making it unbiased, which can help in avoiding insider attacks. Hyperledger Fabric also gives us the flexibility to write our own smart contracts and plug in our own consensus mechanism. * Metaverse platforms: Most of the metaverse platforms available today implement centralized identity mechanisms. The authentication mechanism on one metaverse platform is different from that on other platforms. In our proposed system, we implement decentralized identity using a blockchain identifier called Meta-ID. The metaverse platforms wanting to enhance identity-related security and to have authentication-mechanism uniformity across metaverses need to join this blockchain network. The blockchain-based Metaverse interoperable Identity Framework (MIF) will bring together multiple virtual and physical worlds. * Certificate authority: The certificate authority is a trusted component in our system model. It ensures that unique Meta-IDs are assigned to all physical users, meta-persons, and devices. It is also responsible for initialization of the Metaverse interoperable Identity Framework and for syncing with all of the metaverse platforms that are connected to blockchain. * User: User indicates a physical user like a student, employee, content creator, etc. The user will have an identity in the physical world such as an ID card, student roll number, employee ID, social security number, passport, etc. This physical ID will be mapped in Meta-ID to the virtual ID of an avatar or device. This will ensure that only the legitimate users enter the metaverse. The physical and behavioral attributes of each user will be mapped to an avatar in the virtual world. Other user information like email, phone number, etc., can be collected from the metaverse platform that each user registers on. * Avatar: An avatar is a virtual representation of a user in the virtual world. Avatars have a unique ID associated with them. A user may create multiple avatars. Avatars are assigned a unique Meta-ID during the avatar-registration process. This helps them in avatar-to-avatar mutual authentication. It also helps in avatar-to-device mutual authentication. * Device: Devices can be wearable devices that users in the physical world use to interact with virtual world. They can be AR or VR headsets, hand-held devices, smart glasses, or room-sized devices with multiple degrees of freedom. The device is registered against users and avatars. A unique Meta-ID is assigned to the device. This helps to avoid the stealing of devices or hijacking of device information. * Meta-ID: A Meta-ID is the unique ID used to identify physical users, avatars, and devices across multiple metaverses. It is stored on blockchain to make it secure. Whenever a new avatar is created for the user, a new device is added by the user, the user enters a new metaverse platform, or any physical ID is updated for the user, the Meta-ID will be updated and then broadcast in all associated metaverse platforms to avoid security issues. * Physical ID: A physical ID is proof that a physical user exists. The existing metaverse platforms consider authentication based on virtual IDs only. To map a physical ID with a virtual ID, in our system model, we collect proof of the Physical ID from the user during registration.