I've just created a pull request to merge a first version for supporting Amazon's S3 signature V4 (from now on, AWS4).
The patch implements the basic required primitives to work with AWS4 (sha256 crypto, encoding, and so on), and is able to authenticate HTTP requests that don't include the parameters in the query string (only as HTTP headers) and that do not contain a body. This is work in progress, and I hope to submit a new pull request for this part as soon as possible.
The patch is fully mergeable, so if done it will partially support V4. As said before, I am working on bringing the remaining features.
Note that V2 authentication continues to work as usual.
Any feedback is welcomed.
Pull request is available at:
https://github.com/ceph/ceph/pull/4943