Re: Let us see how to encrypt with Emacs?

[Jean Louis <bugs@gnu.support>]

* tomas@tuxteam.de <tomas@tuxteam.de> [2021-07-09 14:53]:
> On Fri, Jul 09, 2021 at 02:32:10PM +0300, Jean Louis wrote:
> > * Eli Zaretskii <eliz@gnu.org> [2021-07-09 13:40]:
> 
> [...]
> 
> > > No, you don't need to chunk, you just need to pad to a multiple of 64
> > > bytes.
> > 
> > I guess something like this unless I am making an error:
> > 
> > (defun pad-to-multiple-bytes (string max)
> >   "Return string padded to multiple of MAX bytes."
> >   (let* ((bytes (string-bytes string))
> > 	 (multiple (truncate (/ bytes max)))
> > 	 (multiple (if (zerop multiple) max (* (1+ multiple) max))))
> >     (string-pad string multiple)))
> 
> small critiques
> 
>  - see the `ceiling' function: it does what you want (perhaps
>    except at zero.

Thanks, now I know for that:

(defun pad-to-multiple-bytes (string length)
  "Return string padded to multiple of MAX bytes."
  (let* ((bytes (string-bytes string))
	 (multiple (* (ceiling bytes length) length)))
    (string-pad string multiple)))

> I'm not sure you want to encrypt a zero bytes string at all, but
> this might get philosophical)

There may be problems which I will never encounter practically. I know.

>  MAX is an unfortunate variable name for that.

Now is length.

-- 
Jean

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