diff --git a/modoboa/admin/app_settings.py b/modoboa/admin/app_settings.py
index b074e2690..4baa7f38c 100644
--- a/modoboa/admin/app_settings.py
+++ b/modoboa/admin/app_settings.py
@@ -3,6 +3,7 @@ from django.utils.translation import ugettext as _, ugettext_lazy
 from modoboa.lib.formutils import YesNoField, SeparatorField, InlineRadioSelect
 from modoboa.lib.sysutils import exec_cmd
 from modoboa.lib import parameters
+from modoboa.auth.lib import random_key
 
 
 def enabled_applications():
@@ -51,7 +52,7 @@ class GeneralParametersForm(parameters.AdminParametersForm):
 
     secret_key = forms.CharField(
         label=ugettext_lazy("Secret key"),
-        initial="abcdefghijklmnop",
+        initial=random_key(),
         help_text=ugettext_lazy("Key used to encrypt/decrypt passwords")
     )
 
diff --git a/modoboa/auth/lib.py b/modoboa/auth/lib.py
index d256e5294..38e95382d 100644
--- a/modoboa/auth/lib.py
+++ b/modoboa/auth/lib.py
@@ -1,8 +1,21 @@
 # coding: utf-8
 from Crypto.Cipher import AES
 import base64
+import random
+import string
 from modoboa.lib import parameters
 
+
+def random_key(l=16):
+    """Generate a random key
+
+    :param integer l: the key's length
+    :return: a string
+    """
+    char_set = string.printable
+    return ''.join(random.sample(char_set * l, l))
+
+
 def encrypt(clear):
     key = parameters.get_admin("SECRET_KEY", app="admin")
     obj = AES.new(key, AES.MODE_ECB)
@@ -14,11 +27,15 @@ def encrypt(clear):
     ciph = base64.b64encode(ciph)
     return ciph
 
+
 def decrypt(ciph):
-    obj = AES.new(parameters.get_admin("SECRET_KEY", app="admin"), AES.MODE_ECB)
+    obj = AES.new(
+        parameters.get_admin("SECRET_KEY", app="admin"), AES.MODE_ECB
+    )
     ciph = base64.b64decode(ciph)
     clear = obj.decrypt(ciph)
     return clear.rstrip(' ')
 
+
 def get_password(request):
     return decrypt(request.session["password"])