[dynamic] Initial comment/captcha system that doesn't work

9 files changed, 143 insertions, 381 deletions

diff --git a/haunt/api.scm b/haunt/api.scm
index e9c5642..5b5fa2b 100644
--- a/haunt/api.scm
+++ b/haunt/api.scm
@@ -15,6 +15,8 @@
 ;;; <http://www.gnu.org/licenses/>.
 
 (use-modules (ice-9 match)
+             (jakob dynamic capabilities comment-form)
+             (jakob dynamic capabilities comments)
              (jakob dynamic capabilities gallery)
              (jakob dynamic capabilities rsvp)
              (jakob dynamic logging)
@@ -37,13 +39,14 @@
         (args (uri-query (request-uri request))))
     (log-append! 'info (format #f "~a ~a (~a) (~a)" method endpoint args originating-ip)))
   ((match (cons (request-method request) endpoint)
+     (('GET "comment-form" _) get-comment-form)
      ;; ('(GET "challenge") make-challenge)
      ;; ('(GET "comments") get-comments)
-     ;; ('(POST "comment") put-comment)
-     ('(GET "gallery") get-gallery)
-     ('(GET "gallery" "image") get-image)
-     ('(GET "rsvp" "event-info") get-event-info)
-     ('(POST "rsvp") post-event-rsvp)
+     (('POST "comment") put-comment)
+     (('GET "gallery") get-gallery)
+     (('GET "gallery" "image") get-image)
+     (('GET "rsvp" "event-info") get-event-info)
+     (('POST "rsvp") post-event-rsvp)
      (_ (lambda (. args) (not-found request))))
    request body))
 
@@ -71,4 +74,5 @@
           (not-found request)))
     (values (wrap-response response) resp-body)))
 
-(run-server main-request-handler)
+;; (run-server main-request-handler)
+(run-server main-request-handler 'http '(#:port 8081))
diff --git a/haunt/jakob/builder/blog.scm b/haunt/jakob/builder/blog.scm
index b1e19fa..3634de5 100644
--- a/haunt/jakob/builder/blog.scm
+++ b/haunt/jakob/builder/blog.scm
@@ -89,7 +89,8 @@
           ;; ,@(render-comment-view (fetch-webmentions (post-identifier post))))
           ,@(render-comment-view (fetch-comments (post-identifier post))))
       (form
-       (@ (action "https://webmention.io/jakob.space/webmention")
+       (@ (id "webmention-form")
+          (action "https://webmention.io/jakob.space/webmention")
           (method "post"))
        (label "Have you written a "
               ,(hyperlink "https://indieweb.org/responses" "response")
diff --git a/haunt/jakob/dynamic/aes.scm b/haunt/jakob/dynamic/aes.scm
index 11d4819..b6e937d 100644
--- a/haunt/jakob/dynamic/aes.scm
+++ b/haunt/jakob/dynamic/aes.scm
@@ -18,7 +18,9 @@
   #:use-module (gcrypt random)
   #:use-module (system foreign)
   #:use-module (rnrs bytevectors)
-  #:export (new-captcha))
+  #:export (%aes-key-size
+            aes-256-encrypt
+            aes-256-decrypt))
 
 (define %libnettle (dynamic-link "libnettle"))
 (define %aes256-rounds 14)
diff --git a/haunt/jakob/dynamic/base64.scm b/haunt/jakob/dynamic/base64.scm
deleted file mode 100644
index 149f7ba..0000000
--- a/haunt/jakob/dynamic/base64.scm
+++ /dev/null
@@ -1,353 +0,0 @@
-;; -*- mode: scheme; coding: utf-8 -*-
-;;
-;; This module was renamed from (weinholt text base64 (1 0 20100612)) to
-;; (guix base64) by Nikita Karetnikov <nikita@karetnikov.org> on
-;; February 12, 2014.  It was later renamed to (gcrypt base64) by
-;; Christopher Allan Webber <cwebber@dustycloud.org> on May 20, 2017.
-;;
-;; Some optimizations made by Ludovic Courtès <ludo@gnu.org>, 2015.
-;; Turned into a Guile module (instead of R6RS).
-;;
-;; This program is free software: you can redistribute it and/or modify
-;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation, either version 3 of the License, or
-;; (at your option) any later version.
-;;
-;; This program is distributed in the hope that it will be useful,
-;; but WITHOUT ANY WARRANTY; without even the implied warranty of
-;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-;; GNU General Public License for more details.
-;;
-;; You should have received a copy of the GNU General Public License
-;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
-;;
-;; This file incorporates work covered by the following copyright and
-;; permission notice:
-;;
-;;   Copyright © 2009, 2010, 2012, 2013, 2018 Göran Weinholt <goran@weinholt.se>
-;;
-;;   Permission is hereby granted, free of charge, to any person obtaining a
-;;   copy of this software and associated documentation files (the "Software"),
-;;   to deal in the Software without restriction, including without limitation
-;;   the rights to use, copy, modify, merge, publish, distribute, sublicense,
-;;   and/or sell copies of the Software, and to permit persons to whom the
-;;   Software is furnished to do so, subject to the following conditions:
-;;
-;;   The above copyright notice and this permission notice shall be included in
-;;   all copies or substantial portions of the Software.
-;;
-;;   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-;;   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-;;   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-;;   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-;;   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-;;   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-;;   DEALINGS IN THE SOFTWARE.
-
-;; RFC 4648 Base-N Encodings
-
-(define-module (base64)
-  #:export (base64-encode
-            base64-decode
-            base64-alphabet
-            base64url-alphabet
-            get-delimited-base64
-            put-delimited-base64)
-  #:use-module (srfi srfi-11)
-  #:use-module (srfi srfi-60)
-  #:use-module (rnrs bytevectors)
-  #:use-module (rnrs io ports))
-
-
-(define-syntax define-alias
-  (syntax-rules ()
-    ((_ new old)
-     (define-syntax new (identifier-syntax old)))))
-
-;; Force the use of Guile's own primitives to avoid the overhead of its 'fx'
-;; procedures.
-
-(define-alias fxbit-field bit-field)
-(define-alias fxarithmetic-shift ash)
-(define-alias fxarithmetic-shift-left ash)
-(define-alias fxand logand)
-(define-alias fxior logior)
-(define-alias fxxor logxor)
-(define-alias fx=? =)
-(define-alias fx<=? <=)
-(define-alias fxzero? zero?)
-(define-alias fx+ +)
-(define-alias fx- -)
-(define-alias fxmod modulo)
-(define-alias mod modulo)
-
-(define-syntax-rule (assert exp)
-  (unless exp
-    (throw 'assertion-failure 'exp)))
-
-(define base64-alphabet
-  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
-
-(define base64url-alphabet
-  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_")
-
-(define base64-encode
-  (case-lambda
-    ;; Simple interface. Returns a string containing the canonical
-    ;; base64 representation of the given bytevector.
-    ((bv)
-     (base64-encode bv 0 (bytevector-length bv) #f #f base64-alphabet #f))
-    ((bv start)
-     (base64-encode bv start (bytevector-length bv) #f #f base64-alphabet #f))
-    ((bv start end)
-     (base64-encode bv start end #f #f base64-alphabet #f))
-    ((bv start end line-length)
-     (base64-encode bv start end line-length #f base64-alphabet #f))
-    ((bv start end line-length no-padding)
-     (base64-encode bv start end line-length no-padding base64-alphabet #f))
-    ((bv start end line-length no-padding alphabet)
-     (base64-encode bv start end line-length no-padding alphabet #f))
-    ;; Base64 encodes the bytes [start,end[ in the given bytevector.
-    ;; Lines are limited to line-length characters (unless #f),
-    ;; which must be a multiple of four. To omit the padding
-    ;; characters (#\=) set no-padding to a true value. If port is
-    ;; #f, returns a string.
-    ((bv start end line-length no-padding alphabet port)
-     (assert (or (not line-length) (zero? (mod line-length 4))))
-     (let-values (((p extract) (if port
-                                   (values port (lambda () (values)))
-                                   (open-string-output-port))))
-       (letrec ((put (if line-length
-                         (let ((chars 0))
-                           (lambda (p c)
-                             (when (fx=? chars line-length)
-                               (set! chars 0)
-                               (put-char p #\linefeed))
-                             (set! chars (fx+ chars 1))
-                             (put-char p c)))
-                         put-char)))
-         (let lp ((i start))
-           (cond ((= i end))
-                 ((<= (+ i 3) end)
-                  (let ((x (bytevector-uint-ref bv i (endianness big) 3)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (put p (string-ref alphabet (fxbit-field x 6 12)))
-                    (put p (string-ref alphabet (fxbit-field x 0 6)))
-                    (lp (+ i 3))))
-                 ((<= (+ i 2) end)
-                  (let ((x (fxarithmetic-shift-left (bytevector-u16-ref bv i (endianness big)) 8)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (put p (string-ref alphabet (fxbit-field x 6 12)))
-                    (unless no-padding
-                      (put p #\=))))
-                 (else
-                  (let ((x (fxarithmetic-shift-left (bytevector-u8-ref bv i) 16)))
-                    (put p (string-ref alphabet (fxbit-field x 18 24)))
-                    (put p (string-ref alphabet (fxbit-field x 12 18)))
-                    (unless no-padding
-                      (put p #\=)
-                      (put p #\=)))))))
-       (extract)))))
-
-;; Create a lookup table for the alphabet and remember the latest table.
-(define get-decode-table
-  (let ((ascii-table #f)
-        (extra-table '())     ;in the unlikely case of unicode chars
-        (table-alphabet #f))
-    (lambda (alphabet)
-      (unless (eq? alphabet table-alphabet)
-        ;; Rebuild the table.
-        (do ((ascii (make-vector 128 #f))
-             (extra '())
-             (i 0 (+ i 1)))
-            ((= i (string-length alphabet))
-             (set! ascii-table ascii)
-             (set! extra-table extra))
-          (let ((c (char->integer (string-ref alphabet i))))
-            (if (fx<=? c 127)
-                (vector-set! ascii c i)
-                (set! extra (cons (cons c i) extra)))))
-        (set! table-alphabet alphabet))
-      (values ascii-table extra-table))))
-
-;; Decodes a base64 string, optionally ignoring non-alphabet
-;; characters and lack of padding.
-(define base64-decode
-  (case-lambda
-    ((str)
-     (base64-decode str base64-alphabet #f))
-    ((str alphabet)
-     (base64-decode str alphabet #f))
-    ((str alphabet port)
-     (base64-decode str alphabet port #t))
-    ((str alphabet port strict?)
-     (base64-decode str alphabet port strict? #t))
-    ((str alphabet port strict? strict-padding?)
-     (define (pad? c) (eqv? c (char->integer #\=)))
-     (let-values (((p extract) (if port
-                                   (values port (lambda () (values)))
-                                   (open-bytevector-output-port)))
-                  ((ascii extra) (get-decode-table alphabet)))
-       (define-syntax lookup
-         (syntax-rules ()
-           ((_ c) (or (and (fx<=? c 127) (vector-ref ascii c))
-                      (cond ((assv c extra) => cdr)
-                            (else #f))))))
-       (let lp-restart ((str str))
-         (let* ((len (if strict?
-                         (string-length str)
-                         (let lp ((i (fx- (string-length str) 1)))
-                           ;; Skip trailing invalid chars.
-                           (cond ((fxzero? i) 0)
-                                 ((let ((c (char->integer (string-ref str i))))
-                                    (or (lookup c) (pad? c)))
-                                  (fx+ i 1))
-                                 (else (lp (fx- i 1))))))))
-           (let lp ((i 0))
-             (cond
-              ((fx=? i len)
-               (extract))
-              ((fx<=? i (fx- len 4))
-               (let lp* ((c1 (char->integer (string-ref str i)))
-                         (c2 (char->integer (string-ref str (fx+ i 1))))
-                         (c3 (char->integer (string-ref str (fx+ i 2))))
-                         (c4 (char->integer (string-ref str (fx+ i 3))))
-                         (i i))
-                 (let ((i1 (lookup c1)) (i2 (lookup c2))
-                       (i3 (lookup c3)) (i4 (lookup c4)))
-                   (cond
-                    ((and i1 i2 i3 i4)
-                     ;; All characters present and accounted for.
-                     ;; The most common case.
-                     (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                     (fxarithmetic-shift-left i2 12)
-                                     (fxarithmetic-shift-left i3 6)
-                                     i4)))
-                       (put-u8 p (fxbit-field x 16 24))
-                       (put-u8 p (fxbit-field x 8 16))
-                       (put-u8 p (fxbit-field x 0 8))
-                       (lp (fx+ i 4))))
-                    ((and i1 i2 i3 (pad? c4) (= i (- len 4)))
-                     ;; One padding character at the end of the input.
-                     (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                     (fxarithmetic-shift-left i2 12)
-                                     (fxarithmetic-shift-left i3 6))))
-                       (put-u8 p (fxbit-field x 16 24))
-                       (put-u8 p (fxbit-field x 8 16))
-                       (lp (fx+ i 4))))
-                    ((and i1 i2 (pad? c3) (pad? c4) (= i (- len 4)))
-                     ;; Two padding characters.
-                     (let ((x (fxior (fxarithmetic-shift-left i1 18)
-                                     (fxarithmetic-shift-left i2 12))))
-                       (put-u8 p (fxbit-field x 16 24))
-                       (lp (fx+ i 4))))
-                    ((not strict?)
-                     ;; Non-alphabet characters.
-                     (let lp ((i i) (c* '()) (n 4))
-                       (cond ((fxzero? n)
-                              ;; Found four valid characters.
-                              (lp* (cadddr c*) (caddr c*) (cadr c*) (car c*)
-                                   (fx- i 4)))
-                             ((fx=? i len)
-                              (error 'base64-decode
-                                     "Invalid input in non-strict mode."
-                                     i c*))
-                             (else
-                              ;; Gather alphabetic (or valid
-                              ;; padding) characters.
-                              (let ((c (char->integer (string-ref str i))))
-                                (cond ((or (lookup c)
-                                           (and (pad? c)
-                                                (fx<=? n 2)
-                                                (fx=? i (fx- len n))))
-                                       (lp (fx+ i 1) (cons c c*) (fx- n 1)))
-                                      (else
-                                       (lp (fx+ i 1) c* n))))))))
-                    (else
-                     (error 'base64-decode
-                            "Invalid input in strict mode."
-                            c1 c2 c3 c4))))))
-              ((not strict-padding?)
-               ;; Append an appropriate amount of padding after the
-               ;; remaining characters.
-               (if (<= 2 (- len i) 3)
-                   (lp-restart (string-append (substring str i (string-length str))
-                                              (if (= (- len i) 2) "==" "=")))
-                   (error 'base64-decode "The input is too short." i)))
-              (else
-               (error 'base64-decode
-                      "The input is too short, it may be missing padding."
-                      i))))))))))
-
-(define (get-line-comp f port)
-  (if (port-eof? port)
-      (eof-object)
-      (f (get-line port))))
-
-;; Reads the common -----BEGIN/END type----- delimited format from
-;; the given port. Returns two values: a string with the type and a
-;; bytevector containing the base64 decoded data. The second value
-;; is the eof object if there is an eof before the BEGIN delimiter.
-(define get-delimited-base64
-  (case-lambda
-    ((port)
-     (get-delimited-base64 port #t))
-    ((port strict)
-     (define (get-first-data-line port)
-       ;; Some MIME data has header fields in the same format as mail
-       ;; or http. These are ignored.
-       (let ((line (get-line-comp string-trim-both port)))
-         (cond ((eof-object? line) line)
-               ((string-index line #\:)
-                (let lp ()               ;read until empty line
-                  (let ((line (get-line-comp string-trim-both port)))
-                    (if (string=? line "")
-                        (get-line-comp string-trim-both port)
-                        (lp)))))
-               (else line))))
-     (let ((line (get-line-comp string-trim-both port)))
-       (cond ((eof-object? line)
-              (values "" (eof-object)))
-             ((string=? line "")
-              (get-delimited-base64 port))
-             ((and (string-prefix? "-----BEGIN " line)
-                   (string-suffix? "-----" line))
-              (let* ((type (substring line 11 (- (string-length line) 5)))
-                     (endline (string-append "-----END " type "-----")))
-                (let-values ([(outp extract) (open-bytevector-output-port)])
-                  (let lp ((previous "") (line (get-first-data-line port)))
-                    (cond ((eof-object? line)
-                           (error 'get-delimited-base64
-                                  "unexpected end of file"))
-                          ((string-prefix? "-" line)
-                           (unless (string=? line endline)
-                             (error 'get-delimited-base64
-                                    "bad end delimiter" type line))
-                           (values type (extract)))
-                          ((and (= (string-length line) 5)
-                                (string-prefix? "=" line))
-                           ;; Skip Radix-64 checksum
-                           (lp previous (get-line-comp string-trim-both port)))
-                          ((not (fxzero? (fxmod (fx+ (string-length previous)
-                                                     (string-length line))
-                                                4)))
-                           ;; OpenSSH outputs lines with a bad length
-                           (lp (string-append previous line)
-                               (get-line-comp string-trim-both port)))
-                          (else
-                           (base64-decode (string-append previous line) base64-alphabet outp)
-                           (lp "" (get-line-comp string-trim-both port))))))))
-             (else ;skip garbage (like in openssl x509 -in foo -text output).
-              (get-delimited-base64 port)))))))
-
-(define put-delimited-base64
-  (case-lambda
-    ((port type bv line-length)
-     (display (string-append "-----BEGIN " type "-----\n") port)
-     (base64-encode bv 0 (bytevector-length bv)
-                    line-length #f base64-alphabet port)
-     (display (string-append "\n-----END " type "-----\n") port))
-    ((port type bv)
-     (put-delimited-base64 port type bv 76))))
diff --git a/haunt/jakob/dynamic/capabilities/comment-form.scm b/haunt/jakob/dynamic/capabilities/comment-form.scm
index b435089..70e5303 100644
--- a/haunt/jakob/dynamic/capabilities/comment-form.scm
+++ b/haunt/jakob/dynamic/capabilities/comment-form.scm
@@ -15,19 +15,56 @@
 ;;; <http://www.gnu.org/licenses/>.
 
 (define-module (jakob dynamic capabilities comment-form)
+  #:use-module (gcrypt base64)
   #:use-module (haunt html)
   #:use-module (ice-9 match)
+  #:use-module (jakob dynamic captcha)
   #:use-module (jakob dynamic util)
   #:use-module (jakob theme)
   #:use-module (json)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
   #:use-module (web request)
   #:use-module (web response)
   #:use-module (web uri)
   #:export (get-comment-form))
 
+(define (render-comment-form slug)
+  (let-values (((mac solution captcha-image) (new-captcha)))
+    `((div (@ (id "comment-form"))
+        (h1 "Comment form")
+        (form (@ (id "comment-input") (action "/api/comment") (method "post"))
+          (input (@ (type "text") (name "slug") (hidden #t) (value ,slug)))
+          (input (@ (type "text") (name "solution") (hidden #t) (value ,solution)))
+          (input (@ (type "text") (name "solution-mac") (hidden #t) (value ,mac)))
+          (fieldset
+           (legend "Commenter Info")
+           (label (@ (for "name")) "Name:")
+           (input (@ (type "text") (id "name") (name "name") (required #t) (size 24)))
+           (label (@ (for "email")) "Email (optional, used for Gravatar):")
+           (input (@ (type "text") (id "email") (name "email") (size 24)))
+           (label (@ (for "url")) "Webpage URL (optional):")
+           (input (@ (type "text") (id "url") (name "url") (size 24))))
+          (fieldset
+           (legend "Comment")
+           (label (@ (for "subject")) "Subject (optional):")
+           (input (@ (type "text") (id "subject") (name "subject") (size 24)))
+           (label (@ (for "comment")) "Comment :")
+           (textarea (@ (id "coment") (name "comment") (rows 4) (cols 50))))
+          (fieldset
+           (legend "Captcha")
+           (label (@ (for "captcha")) "Captcha:")
+           (img (@ (src ,(format #f "data:image/jpeg;charset=utf-8;base64,~a"
+                                 (base64-encode captcha-image)))))
+           (input (@ (type "text") (id "captcha") (name "captcha") (size 24)))
+          (input (@ (type "submit") (id "submit-form") (value "Submit")))))))))
+
 (define (get-comment-form request body)
   "API endpoint handler for querying for the comments on a particular post
 
 This is a wrapper around `get-comments-by-slug'."
-  (values '((content-type . (text/html)))
-          (sxml->html-string (theme #:content '(p "Hello, world!")))))
+  (let* ((path-encoded (uri-path (request-uri request)))
+         (path (split-and-decode-uri-path path-encoded))
+         (slug (last path)))
+    (values '((content-type . (text/html)))
+            (sxml->html-string (theme #:content (render-comment-form slug) #:title "Comment prompt")))))
diff --git a/haunt/jakob/dynamic/capabilities/comments.scm b/haunt/jakob/dynamic/capabilities/comments.scm
index d4159fa..3e873a6 100644
--- a/haunt/jakob/dynamic/capabilities/comments.scm
+++ b/haunt/jakob/dynamic/capabilities/comments.scm
@@ -16,6 +16,7 @@
 
 (define-module (jakob dynamic capabilities comments)
   #:use-module (ice-9 match)
+  #:use-module (jakob dynamic captcha)
   #:use-module (jakob dynamic util)
   #:use-module (json)
   #:use-module (squee)
@@ -75,9 +76,17 @@ This is a wrapper around `get-comments-by-slug'."
 (define (put-comment request body)
   "API endpoint handler for submitting a comment"
   (define (valid-comment? form-data)
+    (display form-data)
     (and (assoc "slug" form-data)
          (assoc "name" form-data)
-         (assoc "comment" form-data)))
+         (assoc "comment" form-data)
+         (assoc "captcha" form-data)
+         (assoc "solution" form-data)
+         (assoc "solution-mac" form-data)
+         (validate-captcha
+          (assoc-value form-data "captcha")
+          (assoc-value form-data "solution")
+          (assoc-value form-data "solution-mac"))))
   (define (insert-comment form-data)
     (exec-query conn
                 "INSERT INTO comments (submitted, slug, name, subject,
diff --git a/haunt/jakob/dynamic/capabilities/rsvp.scm b/haunt/jakob/dynamic/capabilities/rsvp.scm
index c02b758..d7d6fb9 100644
--- a/haunt/jakob/dynamic/capabilities/rsvp.scm
+++ b/haunt/jakob/dynamic/capabilities/rsvp.scm
@@ -15,7 +15,7 @@
 ;;; <http://www.gnu.org/licenses/>.
 
 (define-module (jakob dynamic capabilities rsvp)
-  #:use-module (base64)
+  #:use-module (gcrypt base64)
   #:use-module (ice-9 binary-ports)
   #:use-module (ice-9 match)
   #:use-module (jakob dynamic util)
diff --git a/haunt/jakob/dynamic/captcha.scm b/haunt/jakob/dynamic/captcha.scm
index b095ebf..3b192cb 100644
--- a/haunt/jakob/dynamic/captcha.scm
+++ b/haunt/jakob/dynamic/captcha.scm
@@ -14,8 +14,8 @@
 ;;; along with this program. If not, see
 ;;; <http://www.gnu.org/licenses/>.
 
-(define-module (captcha)
-  #:use-module (base64)
+(define-module (jakob dynamic captcha)
+  #:use-module (gcrypt base64)
   #:use-module (gcrypt hash)
   #:use-module (gcrypt mac)
   #:use-module (gcrypt random)
@@ -26,10 +26,13 @@
   #:use-module (ice-9 popen)
   #:use-module (ice-9 rdelim)
   #:use-module (ice-9 threads)
+  #:use-module (jakob dynamic aes)
   #:use-module (rnrs bytevectors)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-19)
-  #:export (new-captcha))
+  #:use-module (system foreign)
+  #:export (new-captcha
+            validate-captcha))
 
 (define proc-mutex (make-mutex))
 
@@ -109,26 +112,71 @@
           (error "Cannot generate PNG"))
       data)))
 
-(define (new-uuid)
-  (with-mutex proc-mutex
-    (let* ((port (open-input-pipe "uuidgen"))
-           (str  (read-line port)))
-      (close-pipe port)
-      str)))
+;; These are ephemeral keys. At this point, it doesn't make sense to store keys
+;; locally, since the server process is singular and long-running.
+(define %tex-aes-key (gen-random-bv %aes-key-size))
+(define %tex-mac-key (gen-random-bv 64))
+
+(define (encode-solution solution)
+  (define nonce (gen-random-bv 8))
+  ;; This is horrible :D
+  (define encoded-solution
+    (pointer->bytevector (make-c-struct (list double) (list solution)) 8))
+  (let ((result (make-bytevector 16)))
+    (bytevector-copy! nonce 0 result 0 8)
+    (bytevector-copy! encoded-solution 0 result 8 8)
+    result))
+
+(define (decode-solution encoded)
+  (let ((result (make-bytevector 8)))
+    (bytevector-copy! encoded 8 result 0 8)
+    (first (parse-c-struct (bytevector->pointer result) (list double)))))
 
 (define (new-captcha)
   (let* ((lower-bound (random 10))
          (upper-bound (+ lower-bound 1 (random 9)))
          (expression (random-expression))
-         (latex-src (sexp->latex (simplify-sexp (differentiate-sexp expression)))))
-    (values (new-uuid)
-            (- (local-eval expression (let ((x upper-bound)) (the-environment)))
-               (local-eval expression (let ((x lower-bound)) (the-environment))))
+         (latex-src (sexp->latex (simplify-sexp (differentiate-sexp expression))))
+         (solution (- (local-eval expression (let ((x upper-bound)) (the-environment)))
+                      (local-eval expression (let ((x lower-bound)) (the-environment)))))
+         (ciphertext (base64-encode (aes-256-encrypt %tex-aes-key (encode-solution solution)))))
+    (display solution)
+    (newline)
+    (display (decode-solution (aes-256-decrypt %tex-aes-key (base64-decode ciphertext))))
+    (newline)
+    (values (sign-data-base64 %tex-mac-key ciphertext)
+            ciphertext
             (latex->image (format #f "\\int_{~a}^{~a} ~a \\, dx"
                                   lower-bound
                                   upper-bound
                                   latex-src)))))
 
+(define (validate-captcha answer solution mac)
+  (define epsilon 0.1)
+  (display "Here!")
+  (newline)
+  (display "Valid signature? ")
+  (display (valid-base64-signature? %tex-mac-key solution mac))
+  (newline)
+  (display "Signature was ")
+  (display mac)
+  (newline)
+  (display "Valid answer? ")
+  (display (<= (abs (- (decode-solution (aes-256-decrypt %tex-aes-key (base64-decode solution)))
+                       (string->number answer)))
+               epsilon))
+  (newline)
+  (display "Answer was ")
+  (display (decode-solution (aes-256-decrypt %tex-aes-key (base64-decode solution))))
+  (newline)
+  (display "Solution given was ")
+  (display answer)
+  (newline)
+  (and (valid-base64-signature? %tex-mac-key solution mac)
+       (<= (abs (- (decode-solution (aes-256-decrypt %tex-aes-key (base64-decode solution)))
+                   (string->number answer)))
+           epsilon)))
+
 
 
 ;; How many zeroes the SHA-256 hash has to be prefixed by to be a valid proof of work.
diff --git a/haunt/static/css/style.css b/haunt/static/css/style.css
index 0b32082..4f6def3 100644
--- a/haunt/static/css/style.css
+++ b/haunt/static/css/style.css
@@ -233,20 +233,34 @@ ul#webmention-container .comment .comment-source-identifier {
 
 /* Webmention form. */
 
-form {
+#webmention-form form {
     border-top: 2px solid #d2d6dd;
     padding-top: 1rem;
 }
 
-form input {
+#webmention-form form input {
     margin-top: 1rem;
 }
 
-form input[type=url] {
+#webmention-form form input[type=url] {
     display: block;
     width: 100%;
 }
 
+/* Comment form. */
+
+#comment-form label {
+    display: block;
+    width: 20em;
+    float: left;
+    clear: left;
+}
+
+#comment-form input {
+    width: 20em;
+    float: left;
+}
+
 /* Source code. */
 
 pre {