Explain the working principle of the OAuth protocol and its main components in the authorization process.

OAuth is an authorization protocol that allows third-party applications to obtain limited access to a user's resources on a server without transmitting the password.

Main components of OAuth:

1. Resource Owner — the user who owns the data.
2. Client — the application that wants to access the user's resources.
3. Authorization Server — issues access tokens after successful user authentication.
4. Resource Server — the server where protected resources are stored, access to which is controlled via tokens.

Working principle:

• The client requests permission from the user to access their data.
• After consent, the user authenticates on the authorization server.
• The authorization server issues an access token to the client.
• The client uses this token to access resources on the resource server.

Example of a simplified flow:

User -> Client: Access request
Client -> Authorization Server: Authorization request
Authorization Server -> User: Authentication request
User -> Authorization Server: Provides credentials
Authorization Server -> Client: Sends access token
Client -> Resource Server: Request with access token
Resource Server -> Client: Provides access to resources

Thus, OAuth provides a secure and standardized way to delegate access without transmitting passwords.