AWS CloudFront Support
CloudFront signed URLs and signed cookies.
If only paying or logged-in users should fetch your files, CloudFront can require a signature on each request. We set up key groups, signing in your application and the behavior settings, and track down the 403 errors that come from a wrong policy or key.
When You Need This
The situations where this work pays for itself.
Signs it is time
- Downloads, video or documents must be limited to authorized users
- A signed URL returns 403 or AccessDenied
- You need to protect a whole set of HLS or DASH segments
- You still use root account CloudFront key pairs
- Links must expire or be limited to an IP range
What you get
- Key group, behavior and origin protection in infrastructure as code
- Signing code for your backend with tests
- Secrets Manager storage and a key rotation procedure
- A checklist for debugging signature errors
How we do it
A clear, safe process you can follow along with.
1. Choose URLs or cookies
Signed URLs suit single files and clients that do not support cookies. Signed cookies suit many files, such as video segments or a whole members area, without changing every URL.
2. Create the key pair and key group
We generate an RSA key pair, upload the public key to CloudFront, put it in a key group and store the private key in AWS Secrets Manager, never in the repository or in the front end.
3. Require signing on the behavior
On the cache behavior we set restrict viewer access and choose the trusted key group. Only behaviors that need protection get this, so public assets stay cacheable.
4. Generate signatures in your application
Your backend builds a canned or custom policy with resource, expiry and optional IP condition, signs it with the private key and returns the URL or Set-Cookie headers. We use an SDK helper rather than hand-rolled signing.
5. Keep the origin private
Combined with origin access control, the origin accepts requests only from CloudFront, so the signature cannot be bypassed by going to S3 directly.
6. Troubleshoot and verify
For 403s we check key group association, clock skew, expiry, a resource pattern that does not match the requested path, and cookie domain and path attributes. We test expiry and tampering explicitly.
Mistakes we help you avoid
Common ways this goes wrong, and what we do instead.
Using root account key pairs
That legacy method is discouraged. Key groups can be managed with IAM and rotated.
Very long expiry times
A leaked URL stays valid until expiry. We use short lifetimes and re-sign on demand.
Cookie domain mismatch
Signed cookies must be sent to the CloudFront domain or a matching alternate domain, or the browser never includes them.
Leaving the origin public
Anyone can skip CloudFront if the S3 bucket is still public.
Frequently Asked Questions
What is the difference between signed URLs and signed cookies?
A signed URL grants access to one file. Signed cookies grant access to multiple files that match a policy, without changing the URLs, which suits streaming and member areas.
How do I rotate CloudFront signing keys?
Add a new public key to the key group, start signing with the new private key, wait until old signatures expire, then remove the old key.
Why does my signed URL return access denied?
Typical causes are expiry in the past, a wrong key ID, a policy resource that does not match the path or query string, or a behavior that does not trust the key group.
Want Help With CloudFront signed URLs and signed cookies?
Schedule an appointment. Tell us about your environment and we will outline the safest, highest-value approach.
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