App calls WeChat payment, prompting merchants to illegally pay the order ID; The signature and request parameters are correct. When WeChat pays the order, the merchant illegally pays the order ID.

The reason why the signature is incorrect is that all fields sent to WeChat need to be added and signed in the signature algorithm.

Simply put, the encoding of the output signature and the input signature is inconsistent. In the absence of a unified single interface, some logic of external WeChat payment has changed, which will lead to encoded and uncoded URLs before jumping. In order to be compatible with these two situations, it is necessary to judge and decode the url characteristics, which not only prompts the merchants to pay the order ID illegally.