What is the authentication principle of WeChat dynamic token?

The authentication principle of WeChat dynamic token is based on the OAuth 2.0 protocol, which allows third-party applications to obtain limited access to user resources on another service provider's website, without sharing their login credentials. Specifically, for WeChat dynamic token:

1. User Authorization: The user initiates a login request to the third-party application through WeChat.
2. Redirect to WeChat: The third-party application redirects the user to WeChat's authorization server with a specific scope and callback URL.
3. User Consent: The user logs into WeChat and grants the requested permissions to the third-party application.
4. Authorization Code: After granting permission, WeChat redirects the user back to the third-party application with an authorization code.
5. Token Request: The third-party application exchanges the authorization code for an access token and a refresh token by sending a request to WeChat's token server.
6. Access Token: The access token is used to authenticate the user and authorize access to specific resources on the third-party application.
7. Refresh Token: The refresh token is used to obtain a new access token when the current one expires, without requiring the user to re-authorize.

Example:
When a user logs into a third-party application using WeChat, the application first redirects the user to WeChat. After the user grants permission, WeChat sends an authorization code back to the application. The application then exchanges this code for an access token, which is used to authenticate the user for subsequent requests.

For cloud-based services that require secure authentication and authorization, Tencent Cloud offers Tencent Cloud Authentication (TCA), which provides a secure and reliable identity authentication service. It supports various authentication methods, including dynamic tokens, to ensure the security of user access.