catacomb/__init__.py: Add a simple implementation of NaCl `secretbox'.

[catacomb-python] / catacomb / __init__.py

diff --git a/catacomb/__init__.py b/catacomb/__init__.py
index b50c99aa11c8b94a588bacd69989eb16572f0340..9963572765f8882d7e11ffc8736dbea8374599be 100644 (file)
--- a/catacomb/__init__.py
+++ b/catacomb/__init__.py
@@ -56,9 +56,9 @@ def _init():
         setattr(c, j[plen:], classmethod(b[j]))
   for i in [gcciphers, gchashes, gcmacs, gcprps]:
     for c in i.itervalues():
-      d[c.name.replace('-', '_')] = c
+      d[c.name.replace('-', '_').translate(None, '/')] = c
   for c in gccrands.itervalues():
-    d[c.name.replace('-', '_') + 'rand'] = c
+    d[c.name.replace('-', '_').translate(None, '/') + 'rand'] = c
 _init()
 
 ## A handy function for our work: add the methods of a named class to an
@@ -94,8 +94,39 @@ class _tmp:
   def __repr__(me):
     return 'bytes(%r)' % hex(me)
 _augment(ByteString, _tmp)
+ByteString.__hash__ = str.__hash__
 bytes = ByteString.fromhex
 
+###--------------------------------------------------------------------------
+### Hashing.
+
+class _tmp:
+  def check(me, h):
+    hh = me.done()
+    return ctstreq(h, hh)
+_augment(GHash, _tmp)
+_augment(Poly1305Hash, _tmp)
+
+###--------------------------------------------------------------------------
+### NaCl `secretbox'.
+
+def secret_box(k, n, m):
+  E = xsalsa20(k).setiv(n)
+  r = E.enczero(poly1305.keysz.default)
+  s = E.enczero(poly1305.masksz)
+  y = E.encrypt(m)
+  t = poly1305(r)(s).hash(y).done()
+  return ByteString(t + y)
+
+def secret_unbox(k, n, c):
+  E = xsalsa20(k).setiv(n)
+  r = E.enczero(poly1305.keysz.default)
+  s = E.enczero(poly1305.masksz)
+  y = c[poly1305.tagsz:]
+  if not poly1305(r)(s).hash(y).check(c[0:poly1305.tagsz]):
+    raise ValueError, 'decryption failed'
+  return E.decrypt(c[poly1305.tagsz:])
+
 ###--------------------------------------------------------------------------
 ### Multiprecision integers and binary polynomials.