Generate and use TZ-aware datetime objects

pgpy has been using TZ-naive datetime objects, despite all OpenPGP
wire-format dates being essentially UTC.

Better to represent the datetime objects explicitly as UTC.

Closes: #401

pgpy/packet/packets.py

@@ -8,7 +8,7 @@ import hashlib
 import os
 import re
 
-from datetime import datetime
+from datetime import datetime, timezone
 
 import six
 
@@ -767,7 +767,7 @@ class PubKeyV4(PubKey):
 
     @created.register(int)
     def created_int(self, val):
-        self.created = datetime.utcfromtimestamp(val)
+        self.created = datetime.fromtimestamp(val, timezone.utc)
 
     @created.register(bytes)
     @created.register(bytearray)
@@ -846,7 +846,7 @@ class PubKeyV4(PubKey):
 
     def __init__(self):
         super(PubKeyV4, self).__init__()
-        self.created = datetime.utcnow()
+        self.created = datetime.now(timezone.utc)
         self.pkalg = 0
         self.keymaterial = None
 
@@ -1187,7 +1187,7 @@ class LiteralData(Packet):
 
     @mtime.register(int)
     def mtime_int(self, val):
-        self.mtime = datetime.utcfromtimestamp(val)
+        self.mtime = datetime.fromtimestamp(val, timezone.utc)
 
     @mtime.register(bytes)
     @mtime.register(bytearray)
@@ -1208,7 +1208,7 @@ class LiteralData(Packet):
         super(LiteralData, self).__init__()
         self.format = 'b'
         self.filename = ''
-        self.mtime = datetime.utcnow()
+        self.mtime = datetime.now(timezone.utc)
         self._contents = bytearray()
 
     def __bytearray__(self):

pgpy/packet/subpackets/signature.py

@@ -7,6 +7,7 @@ import calendar
 
 from datetime import datetime
 from datetime import timedelta
+from datetime import timezone
 
 import six
 
@@ -233,7 +234,7 @@ class CreationTime(Signature):
 
     @created.register(int)
     def created_int(self, val):
-        self.created = datetime.utcfromtimestamp(val)
+        self.created = datetime.fromtimestamp(val, timezone.utc)
 
     @created.register(bytearray)
     def created_bytearray(self, val):
@@ -241,7 +242,7 @@ class CreationTime(Signature):
 
     def __init__(self):
         super(CreationTime, self).__init__()
-        self.created = datetime.utcnow()
+        self.created = datetime.now(timezone.utc)
 
     def __bytearray__(self):
         _bytes = super(CreationTime, self).__bytearray__()

pgpy/pgp.py

@@ -20,7 +20,7 @@ import weakref
 
 import six
 
-from datetime import datetime
+from datetime import datetime, timezone
 
 from cryptography.hazmat.primitives import hashes
 
@@ -179,7 +179,7 @@ class PGPSignature(Armorable, ParentRef, PGPObject):
         """
         expires_at = self.expires_at
         if expires_at is not None and expires_at != self.created:
-            return expires_at < datetime.utcnow()
+            return expires_at < datetime.now(timezone.utc)
 
         return False
 
@@ -321,7 +321,7 @@ class PGPSignature(Armorable, ParentRef, PGPObject):
         sig = PGPSignature()
 
         if created is None:
-            created=datetime.utcnow()
+            created=datetime.now(timezone.utc)
         sigpkt = SignatureV4()
         sigpkt.header.tag = 2
         sigpkt.header.version = 4
@@ -717,7 +717,7 @@ class PGPUID(ParentRef):
             return
         mostrecent = None
         attestations = []
-        now = datetime.utcnow()
+        now = datetime.now(timezone.utc)
         fpr = self.parent.fingerprint
         keyid = self.parent.fingerprint.keyid
         for sig in self._signatures:
@@ -1119,7 +1119,7 @@ class PGPMessage(Armorable, PGPObject):
         charset = kwargs.pop('encoding', None)
 
         filename = ''
-        mtime = datetime.utcnow()
+        mtime = datetime.now(timezeone.utc)
 
         msg = PGPMessage()
 
@@ -1133,7 +1133,7 @@ class PGPMessage(Armorable, PGPObject):
         if file and os.path.isfile(message):
             filename = message
             message = bytearray(os.path.getsize(filename))
-            mtime = datetime.utcfromtimestamp(os.path.getmtime(filename))
+            mtime = datetime.fromtimestamp(os.path.getmtime(filename), timezone.utc)
 
             with open(filename, 'rb') as mf:
                 mf.readinto(message)
@@ -1415,7 +1415,7 @@ class PGPKey(Armorable, ParentRef, PGPObject):
         """``True`` if this key is expired, otherwise ``False``"""
         expires = self.expires_at
         if expires is not None:
-            return expires <= datetime.utcnow()
+            return expires <= datetime.now(timezone.utc)
 
         return False