Without the network, how can Alipay and WeChat pay?

A key point of offline payment: payment code can be generated offline.

Payment code generation process:

1. When users open Alipay App, they will apply for token seeds from the server.

2. Alipay server will generate a token seed according to the algorithm and return it to Alipay App；;

3. After Alipay App gets the token seed, it generates the payment code according to the algorithm (it can be generated offline).

The key point of offline payment: the payment code is one-time and updated in real time.

1. The payment code generated by Alipay App will contain information such as user identity and token value;

2. The payment code is one-time and will be updated every minute.

This way, others will not print out your payment code before payment.

Key points of offline payment: the payment code can be offline, and the scanning gun needs to be online.

Payment Code Offline Payment Process:

1. When paying offline, the user opens Alipay App and displays the payment code (offline);

2. The merchant reads the payment code with a code scanner and uploads it to the Alipay server;

3. After receiving the payment code of the merchant, Alipay server compares it with the information stored in the token system;

4. If it is successful, create a payment order and return the order information to the merchant. If the balance is sufficient, the payment can be completed.

In other words, the payer can be offline, but the payee must be online. Through the online payee bridge, the offline payment information is transmitted to Alipay server for verification.

A special case of offline payment: both the payer and the payee are offline.

As mentioned above, offline payment usually requires one of the payer and the payee to be online. But in a special case, both parties can go offline.

In Alipay's urban service, there is the function of public transportation payment, which has been implemented in some cities and some lines. You don't need to bring a bus card or change money when you go out in the future, just bring your mobile phone. Users who enable this function will generate a specific payment code on the page (different from the payment code on Alipay's homepage), and pay through the flower garden, which is also updated every minute.

When users take the bus, they use the bus payment code to pay. However, some bus collection systems are not real-time, and they may be connected to the network as soon as they come down, or they may be connected to the network as soon as they come down. Only when the bus collection system is connected to the network will the fee be deducted.

So in a word, if the phone is offline, it will be verified by the debit computer. If both parties are offline, charge the account first, and then deduct the money when the security verification can be done.