REST API Authentication Methods

Overview

This lecture explains the importance of REST API authentication and details four common authentication methods—basic, bearer, API key, and OAuth 2.0—focusing on their mechanisms, advantages, disadvantages, and relevance for the CCNA exam.

Importance of REST API Authentication

• Authentication verifies the identity of users or systems accessing resources via an API.
• Lack of authentication can expose sensitive data or allow unauthorized modifications.
• Some public APIs are open without authentication, but most require protection.
• APIs may track usage for analytics and billing, often tied to authentication.

Basic Authentication

• Sends a Base64-encoded username and password in the HTTP Authorization header with every request.
• Encoding is not encryption; Base64 can be easily decoded.
• Requires HTTPS for security, as credentials are exposed if intercepted.
• Simple to implement but is less secure since credentials are reused and could be stolen.

Bearer Authentication (Token-Based)

• Uses a token (bearer token) obtained from an authorization (auth) server.
• Client authenticates with the auth server to receive a token, then includes this token in each request.
• Tokens typically expire after a set time to reduce risk if stolen.
• More secure than basic authentication, but still vulnerable if tokens are intercepted.

API Key Authentication

• Client uses a static API key issued by the API provider in each request.
• API key is usually placed in the HTTP Authorization header (not in URLs).
• Useful for tracking usage and easier to implement, but less secure as stolen keys grant access until revoked.
• API keys do not expire automatically and must be rotated manually.

OAuth 2.0 (Access Delegation Framework)

• Allows third-party apps limited access to user resources without sharing user credentials.
• Involves four parties: resource owner, client app, authorization server, resource server.
• Access tokens grant scoped, temporary access; refresh tokens allow new access tokens without user re-login.
• Used in scenarios like “Log in with Google” or social media integration.
• Enhances security and user control over what data is shared.

Key Terms & Definitions

• Authentication — Validating the identity of a user or system to restrict API access.
• Base64 Encoding — A reversible encoding scheme, not encryption; used in basic authentication.
• Bearer Token — A temporary token proving identity; included in requests for authentication.
• API Key — A unique, static key identifying and authenticating API clients.
• OAuth 2.0 — A framework enabling third-party applications to access resources securely with delegated permissions.
• Authorization Server — Issues tokens for authenticated access to resources.
• Resource Server — Hosts the protected data/resources accessed via API.

Action Items / Next Steps

• Review chapter 23 of "Acing the CCNA Exam Volume 2" for further reading on REST API authentication.
• Ensure understanding of the differences and appropriate uses for each authentication method.
• Practice identifying authentication methods and their security implications.