diff --git a/crans_utils.py b/crans_utils.py
index bfdf951..fb3e991 100644
--- a/crans_utils.py
+++ b/crans_utils.py
@@ -34,6 +34,7 @@ import calendar
 import netaddr
 import re
 import time
+import datetime
 import smtplib
 import sys
 import os
@@ -49,6 +50,11 @@ from unicodedata import normalize
 import subprocess
 from netifaces import interfaces, ifaddresses, AF_INET
 
+try:
+    import pytz
+except:
+    pytz = None
+
 DEVNULL = open(os.devnull, 'w')
 
 def find_rid_plage(rid):
@@ -334,3 +340,52 @@ def from_generalized_time_format(gtf):
 
     """
     return time.mktime(time.strptime(gtf.split("-", 1)[0].split("+", 1)[0].split('Z', 1)[0], "%Y%m%d%H%M%S"))
+
+def datetime_from_generalized_time_format(gtf):
+    """Returns a datetime from generalized time format
+
+    """
+    if '-' in gtf or '+' in gtf:
+        date, tz = gtf[0:14], gtf[14:]
+    else:
+        date = gtf.replace("Z", '')
+        tz = '0000'
+    tz = tz.replace('+', '')
+    the_date = datetime.datetime.strptime(date, "%Y%m%d%H%M%S")
+    if pytz is not None:
+        tz_dict = build_tz_dict()
+        the_timezone = tz_dict.get(tz, pytz.utc)
+        the_date = the_timezone.localize(the_date)
+    return the_date
+
+def datetime_to_generalized_time_format(datetime_obj):
+    """Transforms a datetime to a GTF"""
+    if datetime_obj.utcoffset() is None:
+        if pytz is not None:
+            datetime_obj = pytz.utc.localize(datetime_obj)
+            to_append = ""
+        else:
+            to_append = "Z"
+    mostly_gtf = datetime.datetime.strftime(datetime_obj, "%Y%m%d%H%M%S%z")
+    return mostly_gtf.replace('+0000', "Z") + to_append
+
+def build_tz_dict():
+    """Crappy way to define a dict containing all timezones that
+    pytz can handle.
+
+    It seems there is no way to get a tz object from the offset
+    with pytz.
+
+    """
+    tz_dict = {}
+    for tz in pytz.common_timezones:
+        mytz = pytz.timezone(tz)
+        d = datetime.datetime.now(mytz).utcoffset().total_seconds()
+        hours = int(d)/3600
+        minutes = int(float(int(d) % 3600)/60)
+        fmt = "%s%02d%02d" % (sgn(hours), abs(hours), minutes)
+        if fmt not in tz_dict:
+            tz_dict[fmt] = mytz
+    return tz_dict
+
+sgn = lambda x: '-' if x < 0 else ''