DREP introduces zero-knowledge proof in DID to ensure the security of private data. The corresponding zero-knowledge proof is stored in the DID document as verifiable credential so that private data would not be exposed. With DREP’s DID technology and DREP Client, users need only to maintain a single DREP DID private key to access and manage multiple types of digital assets. For example, a verifiable credential D is issued by a trusted third party DID_X to DID_Y. DID_Y’s verifiable credential D, which DID_Z wishes to verify, contains information that is irrelevant to the verification needs, while DID_Y wishes to conceal the irrelevant information from DID_Z. DID_Y can negotiate with DID_Z to verify the necessary information of interest via zero-knowledge proof such that his privacy is protected.