Escher helps you creating secure HTTP requests (for APIs) by signing HTTP(s) requests. It's both a server side and client side implementation. The status is work in progress.
The algorithm is based on Amazon's AWS Signature Version 4, but we have generalized and extended it.
More details will be available at our documentation site.
Check out a [working example] (https://github.com/emartech/escher-ruby-example).