[3.9] bpo-40791: Use CRYPTO_memcmp() for compare_digest (GH-20456) (GH-20461)
hashlib.compare_digest uses OpenSSL's CRYPTO_memcmp() function
when OpenSSL is available.
Note: The _operator module is a builtin module. I don't want to add
libcrypto dependency to libpython. Therefore I duplicated the wrapper
function and added a copy to _hashopenssl.c..
(cherry picked from commit db5aed931f8a617f7b63e773f62db468fe9c5ca1)
Co-authored-by: Christian Heimes <christian@python.org>
diff --git a/Lib/hmac.py b/Lib/hmac.py
index 54a1ef9..180bc37 100644
--- a/Lib/hmac.py
+++ b/Lib/hmac.py
@@ -4,14 +4,15 @@
"""
import warnings as _warnings
-from _operator import _compare_digest as compare_digest
try:
import _hashlib as _hashopenssl
except ImportError:
_hashopenssl = None
_openssl_md_meths = None
+ from _operator import _compare_digest as compare_digest
else:
_openssl_md_meths = frozenset(_hashopenssl.openssl_md_meth_names)
+ compare_digest = _hashopenssl.compare_digest
import hashlib as _hashlib
trans_5C = bytes((x ^ 0x5C) for x in range(256))