anchor.diff:          (n-padding-bytes (- block-size block-offset)))
       (declare (type index end))
       (declare (type (unsigned-byte 8) n-padding-bytes))
  -    (fill text 0 :start (+ start block-offset) :end end)
  -    (setf (aref text (1- end)) n-padding-bytes)
  +    (when (plusp n-padding-bytes)
  +      (fill text 0 :start (+ start block-offset) :end end)
  +      (setf (aref text (1- end)) n-padding-bytes))
       (values)))
   
   (defmethod count-padding-bytes ((padding ansi-x923-padding) text start block-size)
  
positive.code:   (let ((end (+ start block-size))
          (offset (+ start block-offset)))
      (declare (type index end offset))
      (setf (aref text offset) #x80)
      (fill text 0 :start (1+ offset) :end end)
      (values)))
  
  (defmethod count-padding-bytes ((padding iso-7816-4-padding) text start block-size)
  
negative.code:   (declare (type index start block-offset))
    (let ((n-padding-bytes (- block-size block-offset)))
      (declare (type (unsigned-byte 8) n-padding-bytes))
      (when (plusp n-padding-bytes)
        (fill text n-padding-bytes :start (+ start block-offset) :end (+ start block-size)))
      (values)))
  
  (defmethod count-padding-bytes ((padding pkcs7-padding) text start block-size)
  