With the increasing reliance on technology and the growing use of Application Programming Interfaces (APIs), ensuring robust security measures is crucial to protect sensitive data and prevent unauthorized access. In this blog, we will explore the concept of API Security-by-Design and provide valuable insights on how to implement effective security controls for your APIs.

1. When designing an API, it is essential to classify the data and identify regulatory controls during the modeling phase. This step allows you to understand the sensitivity of the data and determine the level of protection required. By categorizing the data, you can prioritize security measures and allocate appropriate resources for their implementation.
2. Once the data is classified, the business service responsible for the data should implement fine-grained data handling and security controls. This involves incorporating measures such as encryption, access control policies, and data integrity checks. By implementing these controls, you ensure that only authorized entities can access and manipulate the data, reducing the risk of data breaches.
3. To further enhance the security of your APIs, it is important to derive API specification security schemes from matching security controls captured by the domain model against templated enterprise security patterns. This approach ensures consistency in security implementation across different APIs and simplifies the management of security-related configurations.
4. API scopes play a vital role in controlling access to API operations. These scopes determine the extent of client access to a resource API. Essentially, an API scope represents an authorization from the owner of a business resource for a client application to call a specific business resource API. API scopes can also be extended to provide role-based end-user access control. API gateways utilize API scopes to make low-granularity access decisions, verifying whether a client or user is registered and has a valid API use-case. On the other hand, access tokens, along with the OIDC identity token, enable high-granularity access control by determining if a user has the right to access the requested data. This multi-layered approach enhances the security of your APIs, offering protection against unauthorized access.
5. When dealing with sensitive APIs, it is crucial to employ specific tactics to ensure their security. Here are some recommended practices:

• API Abstraction : Ensure that your APIs do not expose implementation details. Resource identifiers should be non-sequential and un-guessable, ensuring maximum abstraction from Personally Identifiable Information (PII), primary keys, and creation timestamps. This abstraction minimizes the risk of data leakage and unauthorized access.
• Transport Security: Expose your APIs only through HTTPS TLS-encrypted endpoints. Restrict the supported TLS versions to the latest or older versions, such as TLS 1.3 or 1.2. Additionally, secure your resource server APIs further by implementing Mutual Authentication (MA) from the API Gateway. This additional layer of security ensures that only authorized entities can communicate with your APIs.
• Data Confidentiality, Integrity, and Non-Repudiation: Certain regulatory controls or agreements may require special handling of data. It is essential to carefully validate these requirements and establish a coherent and consistent enterprise approach. By ensuring data confidentiality, integrity, and non-repudiation, you can mitigate potential vulnerabilities and minimize maintenance burdens.
• API Testing : Implement 'code-first' API publishing automation that incorporates Policy-as-Code controls and security testing. This approach allows you to identify and rectify security vulnerabilities early in the development process. Additionally, consider adopting API security testing concepts to further enhance the robustness of your APIs.
• Gateway Security Features: Leverage the security policy features provided by API Gateway platforms to augment the security of your back-end APIs. These features offer defense-in-depth by implementing additional security measures such as request throttling, IP whitelisting, and payload validation. By utilizing these gateway security features, you can strengthen overall API security.

API Security-by-Design is essential to ensure robust protection for your APIs. By following the best practices mentioned in this article, you can establish a secure foundation for your APIs and safeguard sensitive data from unauthorized access. Remember, investing in API security is an investment in the trust and integrity of your business operations.