分布式数字身份中 DIDComm 协议研究

Decentralized digital identity is an emerging identity management technique that allows users to create their own decentralized identifier (DID). By controlling the private key associated with the DID, users can manage verifiable credentials (VC) related to their attributes (e.g., age, permissions). They can also disclose all or part of these credentials to third parties as needed to prove possession of certain attributes. To ensure the secure transfer of critical data, such as decentralized identifiers and verifiable credentials among users, decentralized digital identity adopts the DIDComm protocol proposed by the Hyperledger Foundation’s Aries project. DIDComm is a secure messaging protocol that provides users with multiple methods for establishing communication keys, thereby enabling various secure messaging modes, such as sender-anonymous or authenticated communication. This study provides a comprehensive introduction to the DIDComm protocol from multiple dimensions, including system model, message formats, and security. It also offers a detailed comparison and analysis of DIDComm with several existing secure messaging protocols. Moreover, this study is the first to formally model the security of communication key establishment within the DIDComm protocol, presenting a security model that captures the indistinguishability security of DIDComm’s communication keys. Additionally, the study reviews the current applications of the DIDComm protocol. Finally, it concludes with a summary and discusses the future research and application prospects of the DIDComm protocol.