(defparameter *testhmac* "currency=BTC&version=1&cmd=get_callback_address&key=your_api_public_key&format=json")

(defparameter *test-private* (babel:string-to-octets "test" :encoding :UTF-8))

(defun test-hmac ()
  (let ((hmac (ironclad:make-hmac *test-private* :sha512))
        (sha512 (ironclad:make-digest :sha512)))    
    (ironclad:byte-array-to-hex-string 
     ;; (ironclad:digest-sequence sha512
     (ironclad:hmac-digest hmac :buffer
                           (babel:string-to-octets
                            *testhmac*)))))

;;supposed to be
#||
"5590eac015e7692902e1a9cd5464f1d305a4b593d2f1343d826ac5affc5ac6f960a5167284f9bf31295cba0e04df9d8f7087935b5344c468ccf2dd036e159102"
||#