*4.2. Service Scenarios and Data Flow*

The service scenarios include the transfer between cryptocurrency-1 and cryptocurrency-2, the transfer between cryptocurrency-1 and CBDC-1, and the transfer between CBDC-1 and CBDC-2. The service scenario for the transfer between cryptocurrency-1 and CBDC-1 and the service scenario for the transfer between CBDC-1 and CBDC-2 are very similar to the service scenario for the transfer between cryptocurrency-1 and cryptocurrency-2.

In Figure 6, the service scenario for the transfer between the cryptocurrency-1 and cryptocurrency-2 is describes as follows:


from the transfer agent's wallet to the beneficiary's wallet is stored in blockchain-2. For example, the ledger data include the transfer date, the transfer agent's wallet address, the beneficiary's wallet address, the CBDC-1 amount, and the fee amount for the blockchain-2;

8. The record for the cryptocurrency-2 transfer from the transfer agent's wallet to the beneficiary's wallet is stored in BIMS. Examples of the record data include the transfer date, the transfer agent's wallet address, the beneficiary's wallet address, the cryptocurrency-2 amount, the fee amount for the blockchain-2, and the fee amount for the transfer agent of blockchain-2. In the transfer between CBDC-1 and CBDC-2, the record for the CBDC-2 transfer from the transfer agent's wallet to the beneficiary's wallet is stored in BIMS. Examples of the record data include the transfer date, the transfer agent's wallet address, the beneficiary's wallet address, the CBDC-2 amount, the fee amount for the blockchain-2, and the fee amount for the transfer agent of the blockchain-2. In the transfer between cryptocurrency-1 and CBDC-1, the record for the CBDC-1 transfer from the transfer agent's wallet to the beneficiary's wallet is stored in BIMS. Examples of the record data include the transfer date, the transfer agent's wallet address, the beneficiary's wallet address, the CBDC-1 amount, the fee amount for the blockchain-2, and the fee amount for the transfer agent of blockchain-2.

**Figure 6.** The service scenario for the transfer between the cryptocurrency-1 and cryptocurrency-2.

### **5. Security Threats and Requirements**

Security threats (STs) to the proposed service model for the transfer between cryptocurrencies and CBDCs are identified and security requirements (SRs) countering the security threats are specified in this section.
