Re: Happy new year to CLISP

> On 31 Dec 2016, at 13:02, Jean Louis <[email protected]> wrote:
> 
> I wish to all Happy New Year, to CLISP users.
> 
> While learning, I am wondering, how to use this function:
> 
> (encrypt (ext:convert-string-to-bytes "Hello there" "utf-8") t)
> 
> *** - ENCRYPT: #(72 101 108 108 111 32 116 104 101 114 101) is not of type (VECTOR (UNSIGNED-BYTE 8) 8)
> 
> as:
> 
> [59]> (type-of (convert-string-to-bytes "Hello there" "utf-8"))
> (SIMPLE-ARRAY (UNSIGNED-BYTE 8) (11))
> 
> while implementation notes say, it should return the byte vector. How
> can I convert simple array to byte vector?
> 
> 
> (EXT:CONVERT-STRING-TO-BYTES string encoding &KEY :START :END)
> converts the subsequence of string from start to end to a (VECTOR
> (UNSIGNED-BYTE 8)), according to the given encoding, and returns the
> resulting byte vector.



You have a simple-array of 1x11 octets, and the function expects a vector of 8 octets.
Since there’s this difference of size, we may assume that the encrypt function cannot process the whole 11 octets at once.  You will have to apply it block-by-block.

Perhaps something like:

(defun encrypt-message (clear)
  (let* ((block-size 8)
         (buffer     (make-array block-size                          :element-type '(unsigned-byte 8)))
         (text       (make-array (ceiling (length clear) block-size) :element-type '(unsigned-byte 8))))
    (loop
      :for start :from 0 :by block-size
      :for end   := (+ start block-size)
      :while (< start (length clear))
      :do (replace buffer clear :start2 start)
          (when (< (length clear) end)   ; fillup last block
            (fill buffer 0 :start (- end (length clear)) :end block-size))
          (encrypt buffer t)
          (replace text buffer :start1 start)
      :finally (return text (length clear)))))

(encrypt-message (convert-string-to-bytes "Hello there" "utf-8”))


-- 
__Pascal J. Bourguignon__



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