Can you put permissions on S3 file storage?

Question

Can you put permissions on files that are uploaded to S3?

Or if someone knows the guild/url to the file they can access it publicly?

If yes, what kind of permissions can we set?

Answer 1

Permissions are implemented with a key mechanism. You can make content readable for everyone (no password) or require a password. You grant upload privileges by generating a keyed URI which you can limit to a maximum bandwidth.

Amazon FAQ about access

Amazon documentation on authentication and access control

As dcaunt states, query string authentication requires an expiration date.