HMAC Authentication in the R language platform

I need to be able to use the R language to gather some data from a website. The website has an API that requires authentication. Authentication is performed by signing each request using HMAC-SH512. I attempted to use the package ROAuth but did not have any luck. There are already php implementations of this authentication. All the project worker needs to do is to translate this into the R language. ## Deliverables The information on authentication is at [login to view URL] There is php and python examples on the website.