anchor.diff:               `(defmethod decrypt-with-mode ((cipher ,cipher-specializer)
                                               (mode padded-cipher-mode)
                                               ciphertext plaintext
  -                                            &key (ciphertext-start 0)
  -                                            ciphertext-end
  -                                            (plaintext-start 0)
  -                                            handle-final-block)
  +                                            ciphertext-start ciphertext-end
  +                                            plaintext-start handle-final-block)
                   (declare (type simple-octet-vector plaintext ciphertext))
                   (declare (ignorable handle-final-block))
                   (let ,block-length-binding
  
positive.code:                      with iv-position of-type (integer 0 ,(if (constantp `,block-length-expr)
                                                                `(,block-length-expr)
                                                                '*)) = (iv-position mode)
                       with ciphertext-end = (or ciphertext-end (length ciphertext))
                       with encrypt-function of-type function = (encrypt-function cipher)
                       for i from ciphertext-start below ciphertext-end
                       for j from plaintext-start
  
negative.code:                                                 block-length-expr)
               `(defmethod encrypt-with-mode ((cipher ,cipher-specializer)
                                              (mode cbc-mode) plaintext ciphertext
                                              plaintext-start plaintext-end
                                              ciphertext-start handle-final-block)
                  (declare (type simple-octet-vector plaintext ciphertext))
                  (declare (ignorable handle-final-block))
                  (let ,block-length-binding
  