Computing an HMAC-SHA signature

Question

I'm writing a module for Amazon's SimpleDB. They require REST requests to be signed using HMAC-SHA algorithm. (Details here.)

I'm told that there is a function to computer this signature, but I can't find it in the documentation. What is the function called, and what do its arguments look like?

Answer 1

EDITED: The following should work:

pre {
  message = "Four score and seven years ago";
  key = "Abe Lincoln";
  signature = math:hmac_sha256_base64(message, key);
}
notify("Signature is", signature);

The function is math:hmac_sha256_base64(<datastring>,<keystring>)