Caching HTTP responses can pose security risks, especially for sensitive data, as cached responses might be accessed by unauthorized users (e.g., on a shared device). The goal is to identify the HTTP response header that prevents caching in the most secure way. Let’s evaluate the options:
Option A ("Cache-Control: no-cache, no-store"): Correct. The Cache-Control header with no-cache instructs clients to revalidate with the server before using a cached copy, and no-store prohibits caching entirely (no storage in any cache, including browser, proxy, or CDN). This combination ensures the response is not cached, providing the most secure prevention of caching for sensitive data.
Option B ("Secure-Cache: Enabled"): There is no standard HTTP header called Secure-Cache. This appears to be a made-up option and is not a valid mechanism for controlling caching.
Option C ("Cache-Control: Private"): The Cache-Control: Private directive allows caching but restricts it to the user’s private cache (e.g., browser cache), preventing shared caches (e.g., proxies) from storing the response. However, it still permits caching in the browser, which is less secure than preventing all caching, especially for sensitive data.
Option D ("Content-Security-Policy: no-cache, no-store"): The Content-Security-Policy (CSP) header is used to mitigate XSS and other attacks by controlling which resources can be loaded (e.g., scripts, images). It does not control caching, and no-cache, no-store are not valid CSP directives. This is incorrect.
The correct answer is A, as Cache-Control: no-cache, no-store is the most secure way to prevent caching, aligning with the CAP syllabus under "HTTP Headers Security" and "Sensitive Data Protection."References: SecOps Group CAP Documents - "HTTP Caching Security," "Cache-Control Directives," and "OWASP Secure Headers Project" sections.
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