What consensus mechanism will be used for Central Bank Digital Currencies (CBDCs)?

In our increasingly digital world, transactions are processed online more frequently, reducing the use of physical money. As a result, central banks around the globe have begun considering the best way to introduce digital fiat currency. The International Monetary Fund (IMF) defines CBDC as the digital currency issued by central banks [AMO]. According to a recent survey conducted by the Bank for International Settlements , 80% of central banks are currently working on the development of prototypes for CBDCs. . Naturally, in the development of CBDCs, central banks have looked to cryptocurrencies as a natural reference for this type of problem. However, there are significant differences between decentralised blockchain-based cryptocurrencies and fiat money, particularly regarding regulatory oversight and required functionality. Therefore, future digital fiat currencies must do more than copy the model of decentralised cryptocurrencies due to technological differences and related issues. However, even if the final choice has yet to be made, CBDCs will likely be based on blockchain technology. If this decision is confirmed, one of the most crucial technological aspects during the move towards digital fiat currencies will be selecting the consensus mechanism. The choice of consensus mechanism depends on whether the blockchain is permissioned or permissionless. Two popular cryptocurrencies, Bitcoin and Ethereum, operate under a permissionless system. This means no central authority controls the network, but cryptocurrencies still face technological challenges like the Buterin trilemma. According to this concept, it is not easy to achieve scalability, security, and decentralisation simultaneously