anchor.diff:    (multiple-value-bind (efun dfun) (mode-crypt-functions cipher mode)
       (setf (slot-value mode 'encrypt-function) efun
             (slot-value mode 'decrypt-function) dfun)))
  -
  -#+nil
  -(defmethod initialize-instance :after ((mode padded-cipher-mode)
  -                                       &key buffer-length)
  -  (setf (slot-value mode 'buffer)
  -        (make-array buffer-length :element-type '(unsigned-byte 8))))
   
   (defvar *supported-modes* (list :ecb :cbc :ofb :cfb :cfb8 :ctr))
   
  
positive.code: (defclass ctr-mode (encryption-mode inititialization-vector-mixin)
    ((keystream-blocks :accessor keystream-blocks :initform 0)))
  
  #+nil
  (defclass padded-cipher-mode (encryption-mode)
    ((buffer :reader buffer)
     (buffer-index :accessor buffer-index :initform 0)
     (sub-mode :reader sub-mode :initarg :sub-mode)))
  
  (defmethod print-object ((object encryption-mode) stream)
    (print-unreadable-object (object stream :identity t)
      (format stream "~A" (class-name (class-of object)))))
  
negative.code:                 length)))
    (define-mode-function mode-crypt message-length))
  
  (defmethod mode-crypt-functions (cipher (mode stream-mode))
    (flet ((stream-crypt-function (function)
             (declare (type function function))
  