diff --git a/mayan/apps/common/classes.py b/mayan/apps/common/classes.py
index e8c4b9c252..8aef2dbd7d 100644
--- a/mayan/apps/common/classes.py
+++ b/mayan/apps/common/classes.py
@@ -4,7 +4,6 @@ from django.core.exceptions import PermissionDenied
 from django.db import models
 from django.utils.translation import ugettext
 
-from acls.models import AccessControlList
 from permissions import Permission
 
 
@@ -126,6 +125,8 @@ class Filter(object):
         return unicode(self.label)
 
     def get_queryset(self, user):
+        from acls.models import AccessControlList
+
         queryset = self.model.objects.all()
         for kwargs in self.filter_kwargs:
             queryset = queryset.filter(**kwargs)
diff --git a/mayan/apps/common/widgets.py b/mayan/apps/common/widgets.py
index 32033da86f..2dfd6551ee 100644
--- a/mayan/apps/common/widgets.py
+++ b/mayan/apps/common/widgets.py
@@ -3,7 +3,7 @@ from __future__ import unicode_literals
 import os
 
 from django import forms
-from django.forms.util import flatatt
+from django.forms.utils import flatatt
 from django.utils.encoding import force_unicode, force_text
 from django.utils.html import conditional_escape, format_html
 from django.utils.safestring import mark_safe
diff --git a/mayan/apps/document_signatures/apps.py b/mayan/apps/document_signatures/apps.py
index 69dc4a245b..f9e807da6d 100644
--- a/mayan/apps/document_signatures/apps.py
+++ b/mayan/apps/document_signatures/apps.py
@@ -1,14 +1,11 @@
 from __future__ import unicode_literals
 
-import io
 import logging
 
 from django.utils.translation import ugettext_lazy as _
 
 from acls import ModelPermission
 from common import MayanAppConfig, menu_facet, menu_sidebar
-from django_gpg.exceptions import GPGDecryptionError
-from django_gpg.runtime import gpg
 from documents.models import Document, DocumentVersion
 
 from .hooks import document_pre_open_hook, document_version_post_save_hook
@@ -34,8 +31,6 @@ class DocumentSignaturesApp(MayanAppConfig):
     def ready(self):
         super(DocumentSignaturesApp, self).ready()
 
-        DocumentVersionSignature = self.get_model('DocumentVersionSignature')
-
         DocumentVersion.register_post_save_hook(
             1, document_version_post_save_hook
         )
diff --git a/mayan/apps/document_signatures/hooks.py b/mayan/apps/document_signatures/hooks.py
new file mode 100644
index 0000000000..4dcf94dcd7
--- /dev/null
+++ b/mayan/apps/document_signatures/hooks.py
@@ -0,0 +1,43 @@
+from __future__ import unicode_literals
+
+import io
+import logging
+
+from django_gpg.exceptions import GPGDecryptionError
+from django_gpg.runtime import gpg
+
+logger = logging.getLogger(__name__)
+
+
+def document_pre_open_hook(descriptor, instance):
+    from .models import DocumentVersionSignature
+
+    if DocumentVersionSignature.objects.has_embedded_signature(document_version=instance):
+        # If it has an embedded signature, decrypt
+        try:
+            result = gpg.decrypt_file(descriptor, close_descriptor=False)
+            # gpg return a string, turn it into a file like object
+        except GPGDecryptionError:
+            # At least return the original raw content
+            descriptor.seek(0)
+            return descriptor
+        else:
+            descriptor.close()
+            return io.BytesIO(result.data)
+    else:
+        return descriptor
+
+
+def document_version_post_save_hook(instance):
+    logger.debug('instance: %s', instance)
+    from .models import DocumentVersionSignature
+
+    try:
+        document_signature = DocumentVersionSignature.objects.get(
+            document_version=instance
+        )
+    except DocumentVersionSignature.DoesNotExist:
+        document_signature = DocumentVersionSignature.objects.create(
+            document_version=instance
+        )
+        document_signature.check_for_embedded_signature()
diff --git a/mayan/apps/document_states/handlers.py b/mayan/apps/document_states/handlers.py
index 291b9e03d3..35675647dc 100644
--- a/mayan/apps/document_states/handlers.py
+++ b/mayan/apps/document_states/handlers.py
@@ -1,8 +1,8 @@
 from __future__ import unicode_literals
 
-from .models import Workflow
-
 
 def launch_workflow(sender, instance, created, **kwargs):
+    Workflow = sender.get_model('Workflow')
+
     if created:
         Workflow.objects.launch_for(instance)
diff --git a/mayan/apps/documents/handlers.py b/mayan/apps/documents/handlers.py
index c188dc2288..393cc9ec78 100644
--- a/mayan/apps/documents/handlers.py
+++ b/mayan/apps/documents/handlers.py
@@ -2,9 +2,9 @@ from __future__ import unicode_literals
 
 from django.utils.translation import ugettext_lazy as _
 
-from .models import DocumentType
-
 
 def create_default_document_type(sender, **kwargs):
-    if not DocumentType.objects.count():    
+    DocumentType = sender.get_model('DocumentType')
+
+    if not DocumentType.objects.count():
         DocumentType.objects.create(label=_('Default'))
diff --git a/mayan/apps/documents/statistics.py b/mayan/apps/documents/statistics.py
index 95937b9940..12d0a71f49 100644
--- a/mayan/apps/documents/statistics.py
+++ b/mayan/apps/documents/statistics.py
@@ -4,10 +4,10 @@ import datetime
 
 import qsstats
 
-from .models import Document, DocumentPage, DocumentVersion
-
 
 def new_documents_per_month():
+    from .models import Document
+
     qss = qsstats.QuerySetStats(Document.passthrough.all(), 'date_added')
 
     today = datetime.date.today()
@@ -21,6 +21,8 @@ def new_documents_per_month():
 
 
 def new_document_versions_per_month():
+    from .models import DocumentVersion
+
     qss = qsstats.QuerySetStats(DocumentVersion.objects.all(), 'document__date_added')
 
     today = datetime.date.today()
@@ -34,6 +36,8 @@ def new_document_versions_per_month():
 
 
 def new_document_pages_per_month():
+    from .models import DocumentPage
+
     qss = qsstats.QuerySetStats(DocumentPage.objects.all(), 'document_version__document__date_added')
 
     today = datetime.date.today()
@@ -47,6 +51,8 @@ def new_document_pages_per_month():
 
 
 def total_document_per_month():
+    from .models import Document
+
     qss = qsstats.QuerySetStats(Document.objects.all(), 'date_added')
     this_year = datetime.date.today().year
 
@@ -72,6 +78,8 @@ def total_document_per_month():
 
 
 def total_document_version_per_month():
+    from .models import DocumentVersion
+
     qss = qsstats.QuerySetStats(DocumentVersion.objects.all(), 'document__date_added')
     this_year = datetime.date.today().year
 
@@ -97,6 +105,8 @@ def total_document_version_per_month():
 
 
 def total_document_page_per_month():
+    from .models import DocumentPage
+
     qss = qsstats.QuerySetStats(DocumentPage.objects.all(), 'document_version__document__date_added')
     this_year = datetime.date.today().year
 
diff --git a/mayan/apps/metadata/handlers.py b/mayan/apps/metadata/handlers.py
index 9d559dbca2..dc27e86bf0 100644
--- a/mayan/apps/metadata/handlers.py
+++ b/mayan/apps/metadata/handlers.py
@@ -2,7 +2,6 @@ from __future__ import unicode_literals
 
 import logging
 
-from .models import DocumentMetadata
 from .tasks import task_add_required_metadata_type, task_remove_metadata_type
 
 logger = logging.getLogger(__name__)
@@ -37,6 +36,8 @@ def post_post_document_type_change_metadata(sender, instance, **kwargs):
     for metadata in instance.metadata.all():
         metadata.delete(enforce_required=False)
 
+    DocumentMetadata = sender.get_model('DocumentMetadata')
+
     # Add new document type metadata types to document
     for document_type_metadata_type in instance.document_type.metadata.filter(required=True):
         DocumentMetadata.objects.create(
diff --git a/mayan/apps/ocr/apps.py b/mayan/apps/ocr/apps.py
index 2b8afff5b9..bee3e8b293 100644
--- a/mayan/apps/ocr/apps.py
+++ b/mayan/apps/ocr/apps.py
@@ -33,16 +33,19 @@ from .permissions import permission_ocr_document, permission_ocr_content_view
 from .settings import (
     setting_pdftotext_path, setting_tesseract_path
 )
-from .tasks import task_do_ocr
 
 logger = logging.getLogger(__name__)
 
 
 def document_ocr_submit(self):
+    from .tasks import task_do_ocr
+
     task_do_ocr.apply_async(args=(self.latest_version.pk,))
 
 
 def document_version_ocr_submit(self):
+    from .tasks import task_do_ocr
+
     task_do_ocr.apply_async(
         kwargs={'document_version_pk': self.pk},
         countdown=settings_db_sync_task_delay.value
diff --git a/mayan/apps/ocr/handlers.py b/mayan/apps/ocr/handlers.py
index 5d3f769eeb..959398e10b 100644
--- a/mayan/apps/ocr/handlers.py
+++ b/mayan/apps/ocr/handlers.py
@@ -4,7 +4,6 @@ import logging
 
 logger = logging.getLogger(__name__)
 
-from .models import DocumentTypeSettings
 from .settings import setting_auto_ocr
 
 
@@ -16,6 +15,8 @@ def post_version_upload_ocr(sender, instance, **kwargs):
 
 
 def initialize_new_ocr_settings(sender, instance, **kwargs):
+    DocumentTypeSettings = sender.get_model('DocumentTypeSettings')
+
     if kwargs['created']:
         DocumentTypeSettings.objects.create(
             document_type=instance, auto_ocr=setting_auto_ocr.value
diff --git a/mayan/apps/sources/handlers.py b/mayan/apps/sources/handlers.py
index f3c4c163a6..0af79e626b 100644
--- a/mayan/apps/sources/handlers.py
+++ b/mayan/apps/sources/handlers.py
@@ -5,10 +5,11 @@ from django.utils.translation import ugettext_lazy as _
 from converter.models import Transformation
 
 from .literals import SOURCE_UNCOMPRESS_CHOICE_ASK
-from .models import POP3Email, IMAPEmail, WatchFolderSource, WebFormSource
 
 
 def create_default_document_source(sender, **kwargs):
+    WebFormSource = sender.get_model('WebFormSource')
+
     if not WebFormSource.objects.count():
         WebFormSource.objects.create(
             label=_('Default'), uncompress=SOURCE_UNCOMPRESS_CHOICE_ASK
@@ -16,6 +17,8 @@ def create_default_document_source(sender, **kwargs):
 
 
 def copy_transformations_to_version(sender, **kwargs):
+    Transformation = sender.get_model('Transformation')
+
     instance = kwargs['instance']
 
     # TODO: Fix this, source should be previous version
@@ -25,7 +28,11 @@ def copy_transformations_to_version(sender, **kwargs):
     )
 
 
-def initialize_periodic_tasks(**kwargs):
+def initialize_periodic_tasks(sender, **kwargs):
+    POP3Email = sender.get_model('POP3Email')
+    IMAPEmail = sender.get_model('IMAPEmail')
+    WatchFolderSource = sender.get_model('WatchFolderSource')
+
     for source in POP3Email.objects.filter(enabled=True):
         source.save()
 
diff --git a/mayan/apps/statistics/classes.py b/mayan/apps/statistics/classes.py
index 333b288d48..7943e0f6c0 100644
--- a/mayan/apps/statistics/classes.py
+++ b/mayan/apps/statistics/classes.py
@@ -7,8 +7,6 @@ from djcelery.models import PeriodicTask
 
 from mayan.celery import app
 
-from .models import StatisticResult
-
 
 class StatisticNamespace(object):
     _registry = {}
@@ -45,6 +43,8 @@ class Statistic(object):
 
     @staticmethod
     def purge_schedules():
+        from .models import StatisticResult
+
         queryset = PeriodicTask.objects.filter(name__startswith='statistics.').exclude(name__in=Statistic.get_task_names())
 
         for periodic_task in queryset:
@@ -112,12 +112,16 @@ class Statistic(object):
         return 'statistics.task_execute_statistic_{}'.format(self.slug)
 
     def store_results(self, results):
+        from .models import StatisticResult
+
         StatisticResult.objects.filter(slug=self.slug).delete()
 
         statistic_result, created = StatisticResult.objects.get_or_create(slug=self.slug)
         statistic_result.store_data(data=results)
 
     def get_results(self):
+        from .models import StatisticResult
+
         try:
             return StatisticResult.objects.get(slug=self.slug).get_data()
         except StatisticResult.DoesNotExist: