@@ -141,29 +141,29 @@ def __get_openssl_constructor(name):
         return __get_builtin_constructor(name)
 
 
-def __py_new(name, data=b'', **kwargs):
+def __py_new(name, *args, **kwargs):
     """new(name, data=b'', **kwargs) - Return a new hashing object using the
     named algorithm; optionally initialized with data (which must be
     a bytes-like object).
     """
-    return __get_builtin_constructor(name)(data, **kwargs)
+    return __get_builtin_constructor(name)(*args, **kwargs)
 
 
-def __hash_new(name, data=b'', **kwargs):
+def __hash_new(name, *args, **kwargs):
     """new(name, data=b'') - Return a new hashing object using the named algorithm;
     optionally initialized with data (which must be a bytes-like object).
     """
     if name in __block_openssl_constructor:
         # Prefer our builtin blake2 implementation.
-        return __get_builtin_constructor(name)(data, **kwargs)
+        return __get_builtin_constructor(name)(*args, **kwargs)
     try:
-        return _hashlib.new(name, data, **kwargs)
+        return _hashlib.new(name, *args, **kwargs)
     except ValueError:
         # If the _hashlib module (OpenSSL) doesn't support the named
         # hash, try using our builtin implementations.
         # This allows for SHA224/256 and SHA384/512 support even though
         # the OpenSSL library prior to 0.9.8 doesn't provide them.
-        return __get_builtin_constructor(name)(data)
+        return __get_builtin_constructor(name)(*args, **kwargs)
 
 
 try:
 
@@ -12,6 +12,7 @@
 import itertools
 import logging
 import os
+import re
 import sys
 import sysconfig
 import tempfile
@@ -141,11 +142,10 @@ def __init__(self, *args, **kwargs):
         # of hashlib.new given the algorithm name.
         for algorithm, constructors in self.constructors_to_test.items():
             constructors.add(getattr(hashlib, algorithm))
-            def _test_algorithm_via_hashlib_new(data=None, _alg=algorithm, **kwargs):
-                if data is None:
-                    return hashlib.new(_alg, **kwargs)
-                return hashlib.new(_alg, data, **kwargs)
-            constructors.add(_test_algorithm_via_hashlib_new)
+            def c(*args, __algorithm_name=algorithm, **kwargs):
+                return hashlib.new(__algorithm_name, *args, **kwargs)
+            c.__name__ = f'do_test_algorithm_via_hashlib_new_{algorithm}'
+            constructors.add(c)
 
         _hashlib = self._conditional_import_module('_hashlib')
         self._hashlib = _hashlib
@@ -250,6 +250,75 @@ def test_usedforsecurity_false(self):
             self._hashlib.new("md5", usedforsecurity=False)
             self._hashlib.openssl_md5(usedforsecurity=False)
 
+    @unittest.skipIf(get_fips_mode(), "skip in FIPS mode")
+    def test_clinic_signature(self):
+        for constructor in self.hash_constructors:
+            with self.subTest(constructor.__name__):
+                constructor(b'')
+                constructor(data=b'')
+                constructor(string=b'')  # should be deprecated in the future
+
+            digest_name = constructor(b'').name
+            with self.subTest(digest_name):
+                hashlib.new(digest_name, b'')
+                hashlib.new(digest_name, data=b'')
+                hashlib.new(digest_name, string=b'')
+                if self._hashlib:
+                    self._hashlib.new(digest_name, b'')
+                    self._hashlib.new(digest_name, data=b'')
+                    self._hashlib.new(digest_name, string=b'')
+
+    @unittest.skipIf(get_fips_mode(), "skip in FIPS mode")
+    def test_clinic_signature_errors(self):
+        nomsg = b''
+        mymsg = b'msg'
+        conflicting_call = re.escape(
+            "'data' and 'string' are mutually exclusive "
+            "and support for 'string' keyword parameter "
+            "is slated for removal in a future version."
+        )
+        duplicated_param = re.escape("given by name ('data') and position")
+        unexpected_param = re.escape("got an unexpected keyword argument '_'")
+        for args, kwds, errmsg in [
+            # Reject duplicated arguments before unknown keyword arguments.
+            ((nomsg,), dict(data=nomsg, _=nomsg), duplicated_param),
+            ((mymsg,), dict(data=nomsg, _=nomsg), duplicated_param),
+            # Reject duplicated arguments before conflicting ones.
+            *itertools.product(
+                [[nomsg], [mymsg]],
+                [dict(data=nomsg), dict(data=nomsg, string=nomsg)],
+                [duplicated_param]
+            ),
+            # Reject unknown keyword arguments before conflicting ones.
+            *itertools.product(
+                [()],
+                [
+                    dict(_=None),
+                    dict(data=nomsg, _=None),
+                    dict(string=nomsg, _=None),
+                    dict(string=nomsg, data=nomsg, _=None),
+                ],
+                [unexpected_param]
+            ),
+            ((nomsg,), dict(_=None), unexpected_param),
+            ((mymsg,), dict(_=None), unexpected_param),
+            # Reject conflicting arguments.
+            [(nomsg,), dict(string=nomsg), conflicting_call],
+            [(mymsg,), dict(string=nomsg), conflicting_call],
+            [(), dict(data=nomsg, string=nomsg), conflicting_call],
+        ]:
+            for constructor in self.hash_constructors:
+                digest_name = constructor(b'').name
+                with self.subTest(constructor.__name__, args=args, kwds=kwds):
+                    with self.assertRaisesRegex(TypeError, errmsg):
+                        constructor(*args, **kwds)
+                with self.subTest(digest_name, args=args, kwds=kwds):
+                    with self.assertRaisesRegex(TypeError, errmsg):
+                        hashlib.new(digest_name, *args, **kwds)
+                    if self._hashlib:
+                        with self.assertRaisesRegex(TypeError, errmsg):
+                            self._hashlib.new(digest_name, *args, **kwds)
+
     def test_unknown_hash(self):
         self.assertRaises(ValueError, hashlib.new, 'spam spam spam spam spam')
         self.assertRaises(TypeError, hashlib.new, 1)
@@ -719,8 +788,6 @@ def check_blake2(self, constructor, salt_size, person_size, key_size,
         self.assertRaises(ValueError, constructor, node_offset=-1)
         self.assertRaises(OverflowError, constructor, node_offset=max_offset+1)
 
-        self.assertRaises(TypeError, constructor, data=b'')
-        self.assertRaises(TypeError, constructor, string=b'')
         self.assertRaises(TypeError, constructor, '')
 
         constructor(
 
@@ -0,0 +1,5 @@
+Built-in HACL* and OpenSSL implementations of hash function constructors
+now correctly accept the same *documented* named arguments. For instance,
+:func:`~hashlib.md5` could be previously invoked as ``md5(data=data)``
+or ``md5(string=string)`` depending on the underlying implementation
+but these calls were not compatible. Patch by Bénédikt Tran.