How do you handle API key and secret revocation and expiration in a distributed system? (2024)

API keys and secrets are credentials that allow clients to access your distributed services securely and with different levels of permissions. However, managing them can be challenging, especially when you need to revoke or expire them for various reasons, such as security breaches, policy changes, or user requests. In this article, you will learn some best practices and techniques to handle API key and secret revocation and expiration in a distributed system.

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• Nikolai Grigoriev Experienced Tech Lead

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Revoking or expiring API keys and secrets is a necessary part of maintaining the security and integrity of your distributed system. For instance, you may need to revoke or expire an API key or secret if it has been compromised or used for unauthorized purposes, exceeded its usage quota, belongs to an inactive user, is no longer needed, or you want to enforce a regular rotation or renewal policy. In this way, you can prevent unauthorized access, reduce the attack surface, and comply with the security and privacy standards and regulations.

When designing API keys and secrets, there are several factors to consider in order to make them difficult to revoke or expire in a distributed system. These include the length and complexity of the API keys and secrets, making them long and random enough to prevent brute force attacks, but not too long or complex to cause performance issues. The format and structure should also be consistent and easy to parse and validate, but not too predictable or revealing. Additionally, the API keys and secrets should be stored securely and encrypted, preferably in a dedicated service or database, and distributed over secure channels such as HTTPS or TLS. You may want to use a centralized or distributed registry or cache to keep track of active and revoked API keys and secrets.

Revoking API keys and secrets in a distributed system can be done in various ways, depending on the design and requirements. Deleting or invalidating the API key or secret from the storage or registry is the simplest and most effective method, though it may require some coordination and synchronization among distributed services. Adding the API key or secret to a revocation list or blacklist allows updating the revocation list without affecting the storage or registry, but can introduce overhead and latency when checking the list. Updating the metadata or status of the API key or secret is a more granular and dynamic approach, as it allows changing attributes or state such as version, expiration date, or scope; however, this may require logic and validation for interpreting and enforcing the metadata or status.

Expiring API keys and secrets is another way to revoke them in a distributed system, but with a predefined and automatic mechanism. This method can reduce the risk of stale or unused API keys and secrets being compromised or abused, while also encouraging users or clients to renew or rotate their API keys and secrets regularly. Additionally, expiring API keys and secrets simplifies the revocation process by eliminating the need for manual intervention or notification. There are different ways to expire API keys and secrets in a distributed system, such as using a fixed or variable expiration date or time, as well as a usage-based or time-based expiration policy. However, these methods may require some coordination and synchronization among services, as well as monitoring and tracking of usage or duration. Furthermore, logic and validation are necessary for enforcing the expiration policy, and some mechanism for notifying users or clients about the expiration may be required.

Testing and monitoring your API key and secret revocation and expiration is essential for ensuring the security and reliability of your distributed system. Automated tests and tools can be used to verify the functionality and performance of your API key and secret revocation and expiration methods and mechanisms, such as unit tests, integration tests, load tests, or security tests. Logging and auditing systems can be used to record and analyze the events and activities related to your API key and secret revocation and expiration, such as loggers, analyzers, or dashboards. Lastly, alerting and notification systems can be used to inform the relevant stakeholders about your API key and secret revocation and expiration, such as email, SMS, or push notifications.

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