App key, abbreviated as API interface verification serial number, is used to verify the legitimacy of API access. To access the API interface of a website, you need the permission of the website to access it. If it is a simple metaphor, it can be understood as the user name of the login website.
Ppkey is calculated according to the user id, which is another way to express the user id to ensure uniqueness. At present, signature mechanism is mostly used, that is, all parameters are calculated through an unexposed secret to generate a requested signature, which has certain timeliness, thus reducing the possibility of forgery and ensuring security.