hamacs/ha-passwords.org

Personal Password Generator

• Overlay Redaction
• Password Generation
• Keybindings

A literate programming version for Emacs code to generate and store passwords.

Overlay Redaction

Love this idea for using a regular expression to redact (or at least, obscure) sensitive information before screen sharing.

  (defun toggle-redact-buffer (regexp)
    "Redact buffer content matching regexp. A space redacts all."
    (interactive (list (read-regexp "Text to Redact (Regexp)" 'regexp-history-last)))
    (let* ((redacted)
           (matches (let ((results '()))
                      (when (string-empty-p regexp)
                        (setq regexp "[[:graph:]]")
                        (setq regexp-history-last regexp)
                        (add-to-history 'regexp-history regexp))
                      (save-excursion
                        (goto-char (point-min))
                        (while (re-search-forward regexp nil t)
                          (push (cons (match-beginning 0) (match-end 0)) results)))
                      (nreverse results))))
      (mapc (lambda (match)
              (dolist (overlay (overlays-in (car match) (cdr match)))
                (setq redacted t)
                (delete-overlay overlay))
              (unless redacted
                (overlay-put (make-overlay (car match) (cdr match))
                             'display (make-string (- (cdr match) (car match)) ?x))))
            matches)))

I’m not sure how often I will use this, so I’m not putting it on a keybinding, also so, I will also not put a name-spacing prefix on the function.

Password Generation

Let's assume that I store a bunch of words in data files:

  (defvar ha-passwords-data-files (list (expand-file-name "adjectives.txt"
                                                          (expand-file-name "data" hamacs-source-dir))
                                        (expand-file-name "colors.txt"
                                                          (expand-file-name "data" hamacs-source-dir))
                                        (expand-file-name "nouns.txt"
                                                          (expand-file-name "data" hamacs-source-dir)))
    "List of file name containing a data lines for our password generator. Order of these files matter.")

  (defvar ha-passwords-data nil
    "Contains a list of lists of words that we can choose.")

You can see where I'm going with this, can't you? Let's read them into list variables.

  (defun ha-passwords--read-data-file (filename)
    (with-temp-buffer
      (insert-file-contents filename)
      (split-string (buffer-string) "\n" t)))

Now we get three or so words from our list of lists:

  (defun ha-passwords-words ()
    (unless ha-passwords-data
      (setq ha-passwords-data
            (--map (ha-passwords--read-data-file it) ha-passwords-data-files)))

    (--map (nth (random (length it)) it) ha-passwords-data))

Let's make a password:

  (defun ha-passwords-generate (&optional separator)
    (unless separator
      (setq separator "-"))

    (let* ((choices '("!" "@" "#" "$" "%" "^" "&" "*"))
           (choice (random (length choices)))
           (number (1+ choice)))
      (->> (ha-passwords-words)
           (s-join separator)
           (s-capitalize)
           (s-append (nth choice choices))
           (s-append (number-to-string number)))))

  (defun generate-password (&optional separator)
    (interactive)
    (let ((passphrase (ha-passwords-generate separator)))
      (kill-new passphrase)
      (message "Random password: %s" passphrase)))

Keybindings

Got make it easy to call:

  (ha-leader "a g" '("generate passwd" . generate-password))