Electronic cash is actually a technology to simulate cash in electronic form. E-cash system attempts to copy the characteristics of cash for online transactions in many aspects: convenience, low cost (or no transaction cost). Anonymity and other attributes. However, not all electronic cash systems meet these characteristics, and most electronic cash systems can provide convenience for small online transactions.

Electronic cash is a mature electronic payment method, which is suitable for small transactions paid through the network.

The characteristics of electronic cash:

1. There should be an agreement and authorization relationship between banks and merchants.

2. Users, merchants and electronic cash banks all need to use electronic cash software.

3. Electronic cash bank is responsible for the transfer of funds between users and merchants.

4. Electronic cash is anonymous to users, and the use of electronic cash can protect users' information.

Flow chart of electronic cash payment:

1. user → merchant: the user sends electronic cash coins to the merchant.

2. Merchant → User: Verify the bank signature on the electronic cash currency. If the verification Is successful, calculate the challenge string d=H 1(A‖B‖is), and then send the challenge string D to the user U, where IS stands for the merchant's account in the bank.

3. User → merchant: The user calculates the response r 1 = d (u1s)+x1modq, R2 = DS+X2modq, and sends it to the merchant (r1,R2).

4. Merchant: Check G 1R 1R2ADB, and if it passes the inspection, accept the user's payment, otherwise refuse.