catacomb/__init__.py: Make KMAC `copy' work.

Two fixes needed:

  * Return the `new' object from `copy'.

  * Introduce a `_bare_new' class method to handle constructing the
    destination object, because `KMAC...' objects need a key argument.

diff --git a/catacomb/__init__.py b/catacomb/__init__.py
index ff771b9..8713ab7 100644 (file)
--- a/catacomb/__init__.py
+++ b/catacomb/__init__.py
@@ -237,7 +237,7 @@ class _ShakeBase (_HashBase):
     me._h = me._SHAKE(perso = perso, func = me._FUNC)
 
   ## Delegate methods...
-  def copy(me): new = me.__class__(); new._copy(me)
+  def copy(me): new = me.__class__._bare_new(); new._copy(me); return new
   def _copy(me, other): me._h = other._h.copy()
   def hash(me, m): me._h.hash(m); return me
   def xof(me): me._h.xof(); return me
@@ -251,6 +251,8 @@ class _ShakeBase (_HashBase):
   def buffered(me): return me._h.buffered
   @property
   def rate(me): return me._h.rate
+  @classmethod
+  def _bare_new(cls): return cls()
 
 class _tmp:
   def check(me, h):
@@ -289,6 +291,8 @@ class KMAC (_ShakeBase):
   def xof(me):
     me.rightenc(0)
     return super(KMAC, me).xof()
+  @classmethod
+  def _bare_new(cls): return cls("")
 
 class KMAC128 (KMAC): _SHAKE = Shake128; _TAGSZ = 16
 class KMAC256 (KMAC): _SHAKE = Shake256; _TAGSZ = 32