[Python-checkins] bpo-40645: Deprecated internal details of hmac.HMAC (GH-20132)
Christian Heimes
webhook-mailer at python.org
Sat May 16 19:05:44 EDT 2020
https://github.com/python/cpython/commit/837f9e42e3a1ad03b340661afe85e67d2719334f
commit: 837f9e42e3a1ad03b340661afe85e67d2719334f
branch: master
author: Christian Heimes <christian at python.org>
committer: GitHub <noreply at github.com>
date: 2020-05-17T01:05:40+02:00
summary:
bpo-40645: Deprecated internal details of hmac.HMAC (GH-20132)
files:
A Misc/NEWS.d/next/Library/2020-05-16-19-34-38.bpo-40645.7ibMt-.rst
M Doc/library/hmac.rst
M Lib/hmac.py
M Lib/test/test_hmac.py
diff --git a/Doc/library/hmac.rst b/Doc/library/hmac.rst
index 57ac8bb16120f..5ad348490eaf6 100644
--- a/Doc/library/hmac.rst
+++ b/Doc/library/hmac.rst
@@ -114,6 +114,12 @@ A hash object has the following attributes:
.. versionadded:: 3.4
+.. deprecated:: 3.9
+
+ The undocumented attributes ``HMAC.digest_cons``, ``HMAC.inner``, and
+ ``HMAC.outer`` are internal implementation details and will be removed in
+ Python 3.10.
+
This module also provides the following helper function:
.. function:: compare_digest(a, b)
diff --git a/Lib/hmac.py b/Lib/hmac.py
index b769876e6f774..54a1ef9bdbdcf 100644
--- a/Lib/hmac.py
+++ b/Lib/hmac.py
@@ -30,6 +30,10 @@ class HMAC:
"""
blocksize = 64 # 512-bit HMAC; can be changed in subclasses.
+ __slots__ = (
+ "_digest_cons", "_inner", "_outer", "block_size", "digest_size"
+ )
+
def __init__(self, key, msg=None, digestmod=''):
"""Create a new HMAC object.
@@ -51,18 +55,18 @@ def __init__(self, key, msg=None, digestmod=''):
raise TypeError("Missing required parameter 'digestmod'.")
if callable(digestmod):
- self.digest_cons = digestmod
+ self._digest_cons = digestmod
elif isinstance(digestmod, str):
- self.digest_cons = lambda d=b'': _hashlib.new(digestmod, d)
+ self._digest_cons = lambda d=b'': _hashlib.new(digestmod, d)
else:
- self.digest_cons = lambda d=b'': digestmod.new(d)
+ self._digest_cons = lambda d=b'': digestmod.new(d)
- self.outer = self.digest_cons()
- self.inner = self.digest_cons()
- self.digest_size = self.inner.digest_size
+ self._outer = self._digest_cons()
+ self._inner = self._digest_cons()
+ self.digest_size = self._inner.digest_size
- if hasattr(self.inner, 'block_size'):
- blocksize = self.inner.block_size
+ if hasattr(self._inner, 'block_size'):
+ blocksize = self._inner.block_size
if blocksize < 16:
_warnings.warn('block_size of %d seems too small; using our '
'default of %d.' % (blocksize, self.blocksize),
@@ -79,21 +83,33 @@ def __init__(self, key, msg=None, digestmod=''):
self.block_size = blocksize
if len(key) > blocksize:
- key = self.digest_cons(key).digest()
+ key = self._digest_cons(key).digest()
key = key.ljust(blocksize, b'\0')
- self.outer.update(key.translate(trans_5C))
- self.inner.update(key.translate(trans_36))
+ self._outer.update(key.translate(trans_5C))
+ self._inner.update(key.translate(trans_36))
if msg is not None:
self.update(msg)
@property
def name(self):
- return "hmac-" + self.inner.name
+ return "hmac-" + self._inner.name
+
+ @property
+ def digest_cons(self):
+ return self._digest_cons
+
+ @property
+ def inner(self):
+ return self._inner
+
+ @property
+ def outer(self):
+ return self._outer
def update(self, msg):
"""Feed data from msg into this hashing object."""
- self.inner.update(msg)
+ self._inner.update(msg)
def copy(self):
"""Return a separate copy of this hashing object.
@@ -102,10 +118,10 @@ def copy(self):
"""
# Call __new__ directly to avoid the expensive __init__.
other = self.__class__.__new__(self.__class__)
- other.digest_cons = self.digest_cons
+ other._digest_cons = self._digest_cons
other.digest_size = self.digest_size
- other.inner = self.inner.copy()
- other.outer = self.outer.copy()
+ other._inner = self._inner.copy()
+ other._outer = self._outer.copy()
return other
def _current(self):
@@ -113,8 +129,8 @@ def _current(self):
To be used only internally with digest() and hexdigest().
"""
- h = self.outer.copy()
- h.update(self.inner.digest())
+ h = self._outer.copy()
+ h.update(self._inner.digest())
return h
def digest(self):
diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index 08086f0e78c83..1f3ec4cb9172d 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -409,11 +409,11 @@ def test_attributes(self):
# Testing if attributes are of same type.
h1 = hmac.HMAC(b"key", digestmod="sha256")
h2 = h1.copy()
- self.assertTrue(h1.digest_cons == h2.digest_cons,
+ self.assertTrue(h1._digest_cons == h2._digest_cons,
"digest constructors don't match.")
- self.assertEqual(type(h1.inner), type(h2.inner),
+ self.assertEqual(type(h1._inner), type(h2._inner),
"Types of inner don't match.")
- self.assertEqual(type(h1.outer), type(h2.outer),
+ self.assertEqual(type(h1._outer), type(h2._outer),
"Types of outer don't match.")
@hashlib_helper.requires_hashdigest('sha256')
@@ -423,10 +423,21 @@ def test_realcopy(self):
h2 = h1.copy()
# Using id() in case somebody has overridden __eq__/__ne__.
self.assertTrue(id(h1) != id(h2), "No real copy of the HMAC instance.")
- self.assertTrue(id(h1.inner) != id(h2.inner),
+ self.assertTrue(id(h1._inner) != id(h2._inner),
"No real copy of the attribute 'inner'.")
- self.assertTrue(id(h1.outer) != id(h2.outer),
+ self.assertTrue(id(h1._outer) != id(h2._outer),
"No real copy of the attribute 'outer'.")
+ self.assertEqual(h1._inner, h1.inner)
+ self.assertEqual(h1._outer, h1.outer)
+ self.assertEqual(h1._digest_cons, h1.digest_cons)
+
+ @hashlib_helper.requires_hashdigest('sha256')
+ def test_properties(self):
+ # deprecated properties
+ h1 = hmac.HMAC(b"key", digestmod="sha256")
+ self.assertEqual(h1._inner, h1.inner)
+ self.assertEqual(h1._outer, h1.outer)
+ self.assertEqual(h1._digest_cons, h1.digest_cons)
@hashlib_helper.requires_hashdigest('sha256')
def test_equality(self):
diff --git a/Misc/NEWS.d/next/Library/2020-05-16-19-34-38.bpo-40645.7ibMt-.rst b/Misc/NEWS.d/next/Library/2020-05-16-19-34-38.bpo-40645.7ibMt-.rst
new file mode 100644
index 0000000000000..19d5a651eb49a
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2020-05-16-19-34-38.bpo-40645.7ibMt-.rst
@@ -0,0 +1,3 @@
+The :class:`hmac.HMAC` exposes internal implementation details. The
+attributes ``digest_cons``, ``inner``, and ``outer`` are deprecated and will
+be removed in the future.
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