Content Security Policy (CSP) for ASP.NET Projects

Content Security Policy (CSP) for ASP.NET Projects

As your site scales or handles sensitive data, a strong Content Security Policy (CSP) becomes essential—not just for security, but for trust, SEO, and performance.

🔹 Think of CSP as your site’s seatbelt—it doesn’t stop traffic accidents, but it protects you when things go wrong.

🔍 script-src vs script-src-elem

script-src

This applies to all JavaScript:

  • Inline scripts
  • External scripts (<script src="">)
  • Dynamically injected scripts

script-src-elem

This targets only external scripts loaded via <script src="">.

Useful when you want to:

  • Allow CDN-hosted JS
  • Disallow inline JS (a common vector for XSS)

script-src 'self';
script-src-elem 'self' https://trusted-cdn.com;

✅ Inline scripts won't work unless 'unsafe-inline' is added

✅ External scripts limited to your domain and trusted CDNs

💡 When to Use Nonces

For inline scripts that must exist, you can generate a nonce dynamically per request:

<script nonce="random123">
  console.log('Hello safely!');
</script>


Content-Security-Policy: script-src 'nonce-random123';

✅ Only scripts with a valid nonce will execute

✅ Removes the need for 'unsafe-inline'

I can help you implement this dynamically in Razor Pages or your layout view.

🧠 What About Hashes?

If your inline scripts don’t change, use a SHA-256 hash instead:

Content-Security-Policy: script-src 'sha256-abc123...';

This is great for static inline JS and allows you to drop 'unsafe-inline'.

✅ TL;DR – When to Upgrade

ScenarioUse
Loading external JS via CDNscript-src-elem
Want to block all inline JSNonces or hashes
Aiming for CSP Level 2/3No 'unsafe-inline', use nonces
XSS-sensitive pagesNonces, script-src-elem, hashes
Lighthouse audit passNonces or hashes

Why This Matters for Your Business

🧠 With over 30 years of business-savvy experience, I understand that security isn't just technical—it's strategic. A strong CSP protects your brand, your users, and your revenue.

Ask me how tightening a site's CSP helped it pass a critical security audit and win an enterprise contract.

Want help setting up a modern CSP in .NET 8?

You can explore my tech stack or see my business credentials—I've already solved this for projects at scale.

✅ Ready to Protect Your Platform?

Request Access to my DevStack or Book a Demo and let’s make your site security audit–proof.

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