# An Empirical Study of a Trustworthy Cloud Common Data Model Using Decentralized Identifiers
## 3 The Extended to Identify Management Scheme for Cloud CDM
### Issuing IRB Credential
That claims from verifiable credentials can be selectively disclosed, meaning that just some data elements from credentials, even across credentials can (and should be) provided in a single presentation. By providing them in a single presentation, the verifier knows that all the credentials were issued to the same entity. Four agents, the researcher, IRB, provider, and consumer are developed. Those agents are written in Python by using ACA-py library. Agents that receive a message from another entity post a webhook internally over HTTP, allowing the controller to respond appropriately. Note that this can include requesting the agent to send further messages in reply. More details can be seen in Table 3.

ACA-py can also notify its controller when an event has occurred. It supports webhooks that allow immediately obtaining an update of what happened. Requests and responses between controllers configured through ACA-py are transmitted as HTTP requests, and webhook notifications are delivered as a result of processing. Webhook is an asynchronous HTTP callback on an event occurrence. It is a simple server-to-server communication for reporting a specific event occurred on a server. The server on which the event occurred will fire an HTTP POST request to another server on a URL that is provided by the receiving server. In this paper, each of the cloud CDM subjects operates their own agents acting as a peer, and transactions between peers are maintained in a distributed ledger. Agent-to-agent communication is based on the DiDComm specification to support bilateral communication through a trusted channel. ### Experimental Result

The simulation environment setup starts with the registration of the entity researcher named [PERSON] on each IRB. To establish the connection between IRB and Alice, IRB advertises an invitation data, Alice delivers the invitation message to IRB, and IRB responds to the accept message associated with the invitation. For peer-to-peer communication, Aries Interop Profile (AIP) uses 20. AIP is used to establish a connection between agents, exchange identity certificates, and perform transmission data through command delivery. After the identity is verified, the user's CDM data credential is performed. After processing the registration information, the IRB sends a unique connection invitation message to [PERSON], as represented in Figure 10. The connection request message is used to communicate the DID document of the invitee ([PERSON]) to the invitee (IRB). The @type attribute is a required string value that denotes that the received message is a connection request. After receiving the connection request, IRB evaluates the provided DID and DID Doc according to the DID Method Spec. Figure 10: JSON format of IRB invitation attribute. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Name** & **HTTP Port** & **Admin API Port** & **Webhook Port** \\ \hline Researcher & 8030 & 8031 & 8032 \\ IRB & 8010 & 8011 & 8012 \\ CDM Provider & 8050 & 8051 & 8052 \\ CDM Consumer & 8060 & 8061 & 8062 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Participating entities and their endpoints. When IRB and researcher agents want to connect with each other, they establish a connection by DIComm, a series of messages that go back and forth to establish a connection and exchange information. In Figure 11, connection_id is used to send a message between two agents. In answer to the connect invitation, the IRB issues and offers a researcher a VC, represented in Figure 12 (segment of the issued credential), to be used to prove his/her identity when connecting to CDM provider. The VC is issued according to its schema definition in Figure 6. The credential is stored in the wallet of the researcher. The credential is generated based on IRB records including IRB number, name, affiliation, the status of GCP, etc. GCP stands for good clinical practice. This means that the clinical studies using CDM satisfy the clinical trial management criteria through the IRB.