4.3 User Service Layer

4.3.1 Wallet

Connect with banks and settlement treasure transfers, provide corresponding cash flow record management, and provide related service support for users to deposit cash and withdraw cash for other business terminals;

4.3.2 Account

It includes basic functions such as user registration, authentication, personal information, password, verification code login, session session and back-end authority verification, etc. It maintains the cash/digital asset records and various transaction order records of users and the platform as a whole, provide asset query and ensure safe and reliable (strong consistency) change services for other business ends; provide asset account balances, orders based on MySQL transaction management with consistency of multi-table states in the process of entrustment/cancellation/transaction, deposit/withdrawal, and coin withdrawal/deposit; read-write separation and cache control for the relevant table library plan of reading more and writing less asset balance information; continuous increase in accumulation The order records consider the hot and cold data sub-database；

4.3.3 Storage

Using a peer-to-peer distributed hypermedia distribution protocol, it can connect all computing devices with the same file management mode, and can be perfectly combined with the blockchain. Users can use IPFS to process large amounts of data, and then encrypt the corresponding encrypted hash. Stored in the blockchain and time stamped. In this way, there is no need to put the data itself on the chain, which not only saves the network bandwidth of the blockchain, but also effectively protects it. Regarding the security of files, on the one hand, it can be encrypted and stored in IPFS, and on the other hand, IPFS can be used to accomplish distributed file sharing.

4.3.4 Privacy protection

On the basis of anonymity, privacy is guaranteed through blind digital signatures. Blind Signature (BlindSignature) is a digital signature method, which means that the message content is invisible to the signer before the message content is signed. Blind signature can effectively protect the content of the signed message because of its blindness. Blind signature allows the message owner to blind the message first, and then let the signer sign the blinded message. Finally, the message owner removes the blind factor from the signature and obtains the signer's signature on the original message. In addition to satisfying the general digital signature conditions, the following two properties must also be satisfied: the message is invisible to the signer, that is, the signer does not know the content of the message he signed; the signed message cannot be traced, that is, when the signature is published the signer had no way of knowing when the message was signed by him.