diff --git a/papers/bibstruct.py b/papers/bibstruct.py
new file mode 100644
index 0000000..8b9f317
--- /dev/null
+++ b/papers/bibstruct.py
@@ -0,0 +1,82 @@
+import unicodedata
+import re
+
+    # citekey stuff
+
+CONTROL_CHARS = ''.join(map(unichr, range(0, 32) + range(127, 160)))
+CITEKEY_FORBIDDEN_CHARS = '@\'\\,#}{~%/'  # '/' is OK for bibtex but forbidden
+# here since we transform citekeys into filenames
+CITEKEY_EXCLUDE_RE = re.compile('[%s]'
+        % re.escape(CONTROL_CHARS + CITEKEY_FORBIDDEN_CHARS))
+
+def str2citekey(s):
+    key = unicodedata.normalize('NFKD', unicode(s)).encode('ascii', 'ignore')
+    key = CITEKEY_EXCLUDE_RE.sub('', key)
+    # Normalize chars and remove non-ascii
+    return key
+
+def check_citekey(citekey):
+    # TODO This is not the right way to test that (17/12/2012)
+    if unicode(citekey) != str2citekey(citekey):
+        raise ValueError("Invalid citekey: %s" % citekey)
+
+def verify_bibdata(bibdata):
+    if not hasattr(bibdata, 'entries') or len(bibdata.entries) == 0:
+        raise ValueError('no entries in the bibdata.')
+    if len(bibdata.entries) > 1:
+        raise ValueError('ambiguous: multiple entries in the bibdata.')
+    
+def get_entry(bibdata):
+    verify_bibdata(bibdata)        
+    return bibdata.entries.iteritems().next()
+
+def extract_citekey(bibdata):
+    verify_bibdata(bibdata)
+    citekey, entry = get_entry(bibdata)
+    return citekey
+
+def generate_citekey(bibdata):
+    """ Generate a citekey from bib_data.
+
+        :param generate:  if False, return the citekey defined in the file, 
+                          does not generate a new one.
+        :raise ValueError:  if no author nor editor is defined.
+    """
+    citekey, entry = get_entry(bibdata)
+
+    author_key = 'author' if 'author' in entry.persons else 'editor'
+    try:
+        first_author = self.bibentry.persons[author_key][0]
+    except KeyError:
+        raise ValueError(
+                'No author or editor defined: cannot generate a citekey.')
+    try:
+        year = self.bibentry.fields['year']
+    except KeyError:
+        year = ''
+    citekey = u'{}{}'.format(u''.join(first_author.last()), year)
+    
+    return str2citekey(citekey)
+    
+def extract_docfile(bibdata, remove=False):
+    """ Try extracting document file from bib data.
+        Returns None if not found.
+
+        :param remove: remove field after extracting information (default: False)
+    """
+    citekey, entry = get_entry(bibdata)
+
+    try:
+        field = entry.fields['file']
+        # Check if this is mendeley specific
+        for f in field.split(':'):
+            if len(f) > 0:
+                break
+        if remove:
+            entry.fields.pop('file')
+        # This is a hck for Mendeley. Make clean
+        if f[0] != '/':
+            f = '/' + f
+        return f
+    except (KeyError, IndexError):
+        return None