API Authentication Methods Explained: API Keys, OAuth, JWT & HMAC Compared

API authentication in enterprise environments is crucial for maintaining security and trust, with different methods offering varying levels of protection and functionality. Authentication (authn) and authorization (authz) are distinct processes, where the former verifies identity and the latter manages access. The text discusses multiple approaches: basic auth, which is insecure due to its simplicity and lack of expiration; API keys, which are easy to implement but can pose security risks if mishandled; OAuth 2.0 and OIDC, which provide a robust framework for delegated access and identity verification; JWTs, which offer stateless authentication but pose challenges in token revocation; and HMAC and mTLS, which ensure data integrity and secure communications, especially in sensitive transactions. The importance of choosing the appropriate method based on performance, security needs, and the nature of business interactions (B2B vs. B2C) is emphasized to avoid future complications and enhance overall system security.