Add document signature verification app

apps/django_gpg/exceptions.py

@@ -0,0 +1,31 @@
+class GPGException(Exception):
+    pass
+
+
+class GPGVerificationError(GPGException):
+    pass
+
+
+class GPGSigningError(GPGException):
+    pass
+
+
+class GPGDecryptionError(GPGException):
+    pass
+
+
+class KeyDeleteError(GPGException):
+    pass
+
+
+class KeyGenerationError(GPGException):
+    pass
+
+
+class KeyFetchingError(GPGException):
+    pass
+
+
+class KeyDoesNotExist(GPGException):
+    pass
+