pyderasn.py | 24 ++++++++++++++++--------

diff --git a/pyderasn.py b/pyderasn.py
index 718c657ace759810195ae5632816b1d1725cde042f104d0d71dd80129dbb6588..1bfe68ff0ca2868621f9538bc46a279389a07d4eb0ee2c6cd4db3a334d9def76 100755
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -1520,6 +1520,8 @@         raise DecodeError("long form instead of short one")
     return l, 1 + octets_num, data[1 + octets_num:]
 
 
+LEN0 = len_encode(0)
+LEN1 = len_encode(1)
 LEN1K = len_encode(1000)
 
 
@@ -2460,11 +2462,7 @@         )
 
     def _encode(self):
         self._assert_ready()
-        return b"".join((
-            self.tag,
-            len_encode(1),
-            (b"\xFF" if self._value else b"\x00"),
-        ))
+        return b"".join((self.tag, LEN1, (b"\xFF" if self._value else b"\x00")))
 
     def _decode(self, tlv, offset, decode_path, ctx, tag_only, evgen_mode):
         try:
@@ -3987,7 +3985,7 @@             optional=self.optional if optional is None else optional,
         )
 
     def _encode(self):
-        return self.tag + len_encode(0)
+        return self.tag + LEN0
 
     def _decode(self, tlv, offset, decode_path, ctx, tag_only, evgen_mode):
         try:
@@ -4783,8 +4781,11 @@     asn1_type_name = "IA5"
 
 
 LEN_YYMMDDHHMMSSZ = len("YYMMDDHHMMSSZ")
+LEN_LEN_YYMMDDHHMMSSZ = len_encode(LEN_YYMMDDHHMMSSZ)
+LEN_YYMMDDHHMMSSZ_WITH_LEN = len(LEN_LEN_YYMMDDHHMMSSZ) + LEN_YYMMDDHHMMSSZ
 LEN_YYYYMMDDHHMMSSDMZ = len("YYYYMMDDHHMMSSDMZ")
 LEN_YYYYMMDDHHMMSSZ = len("YYYYMMDDHHMMSSZ")
+LEN_LEN_YYYYMMDDHHMMSSZ = len_encode(LEN_YYYYMMDDHHMMSSZ)
 
 
 class VisibleString(CommonString):
@@ -5014,8 +5015,7 @@         return self._value.strftime("%y%m%d%H%M%SZ").encode("ascii")
 
     def _encode(self):
         self._assert_ready()
-        value = self._encode_time()
-        return b"".join((self.tag, len_encode(len(value)), value))
+        return b"".join((self.tag, LEN_LEN_YYMMDDHHMMSSZ, self._encode_time()))
 
     def _encode_cer(self, writer):
         write_full(writer, self._encode())
@@ -5180,6 +5180,14 @@         encoded = value.strftime("%Y%m%d%H%M%S")
         if value.microsecond > 0:
             encoded += (".%06d" % value.microsecond).rstrip("0")
         return (encoded + "Z").encode("ascii")
+
+    def _encode(self):
+        self._assert_ready()
+        value = self._value
+        if value.microsecond > 0:
+            encoded = self._encode_time()
+            return b"".join((self.tag, len_encode(len(encoded)), encoded))
+        return b"".join((self.tag, LEN_LEN_YYYYMMDDHHMMSSZ, self._encode_time()))
 
 
 class GraphicString(CommonString):