diff -r 3e436a494ce3 -r 7778a2bbdf9d web/captcha.py
--- a/web/captcha.py	Fri Mar 26 13:21:25 2010 +0100
+++ b/web/captcha.py	Fri Mar 26 13:23:25 2010 +0100
@@ -17,7 +17,7 @@
 from time import time
 
 from cubicweb import tags
-from cubicweb.web import formwidgets as fw
+from cubicweb.web import ProcessFormError, formwidgets as fw
 
 
 def pil_captcha(text, fontfile, fontsize):
@@ -63,7 +63,22 @@
 class CaptchaWidget(fw.TextInput):
     def render(self, form, field, renderer=None):
         # t=int(time()*100) to make sure img is not cached
-        src = form._cw.build_url('view', vid='captcha', t=int(time()*100))
+        src = form._cw.build_url('view', vid='captcha', t=int(time()*100),
+                                 captchakey=field.input_name(form))
         img = tags.img(src=src, alt=u'captcha')
         img = u'<div class="captcha">%s</div>' % img
         return img + super(CaptchaWidget, self).render(form, field, renderer)
+
+    def process_field_data(self, form, field):
+        captcha = form._cw.get_session_data(field.input_name(form), None,
+                                            pop=True)
+        val = super(CaptchaWidget, self).process_field_data(form, field)
+        if val is None:
+            return val # required will be checked by field
+        if captcha is None:
+            msg = form._cw._('unable to check captcha, please try again')
+            raise ProcessFormError(msg)
+        elif val.lower() != captcha.lower():
+            msg = form._cw._('incorrect captcha value')
+            raise ProcessFormError(msg)
+        return val