+ *) Experimental support for use of HMAC via EVP_PKEY interface. This
+ allows HMAC to be handled via the EVP_DigestSign*() interface. The
+ EVP_PKEY "key" in this case is the HMAC key, potentially allowing
+ ENGINE support for HMAC keys which are unextractable. New -mac and
+ -macopt options to dgst utility.
+ [Steve Henson]
+