RustPython · youknowone · Feb 15, 2026 · Feb 15, 2026 · Feb 15, 2026
diff --git a/Lib/hmac.py b/Lib/hmac.py
@@ -159,6 +159,7 @@ def copy(self):
         # Call __new__ directly to avoid the expensive __init__.
         other = self.__class__.__new__(self.__class__)
         other.digest_size = self.digest_size
+        other.block_size = self.block_size
         if self._hmac:
             other._hmac = self._hmac.copy()
             other._inner = other._outer = None

diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
@@ -1066,22 +1066,6 @@ def test_hmac_digest_digestmod_parameter(self):
             ):
                 self.hmac_digest(b'key', b'msg', value)
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_constructor(self):
-        return super().test_constructor()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_constructor_missing_digestmod(self):
-        return super().test_constructor_missing_digestmod()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_constructor_unknown_digestmod(self):
-        return super().test_constructor_unknown_digestmod()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AttributeError: module '_hashlib' has no attribute 'HMAC'. Did you mean: 'exc_type'?
-    def test_internal_types(self):
-        return super().test_internal_types()
-
     @unittest.expectedFailure  # TODO: RUSTPYTHON; AttributeError: module '_hashlib' has no attribute 'hmac_digest'
     def test_digest(self):
         return super().test_digest()
@@ -1137,6 +1121,15 @@ def test_properties(self):
         self.assertEqual(h.digest_size, self.digest_size)
         self.assertEqual(h.block_size, self.block_size)
 
+    def test_copy(self):
+        # Test a generic copy() and the attributes it exposes.
+        # See https://github.com/python/cpython/issues/142451.
+        h1 = self.hmac_new(b"my secret key", digestmod=self.digestname)
+        h2 = h1.copy()
+        self.assertEqual(h1.name, h2.name)
+        self.assertEqual(h1.digest_size, h2.digest_size)
+        self.assertEqual(h1.block_size, h2.block_size)
+
     def test_repr(self):
         # HMAC object representation may differ across implementations
         raise NotImplementedError
@@ -1160,7 +1153,6 @@ def test_repr(self):
 
 
 @hashlib_helper.requires_openssl_hashdigest('sha256')
-@unittest.skip("TODO: RUSTPYTHON; AttributeError: module '_hashlib' has no attribute 'HMAC'")
 class OpenSSLSanityTestCase(ThroughOpenSSLAPIMixin, SanityTestCaseMixin,
                             unittest.TestCase):
 
@@ -1257,18 +1249,6 @@ def HMAC(self, key, msg=None):
     def gil_minsize(self):
         return _hashlib._GIL_MINSIZE
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_update(self):
-        return super().test_update()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; AttributeError: module '_hashlib' has no attribute '_GIL_MINSIZE'
-    def test_update_large(self):
-        return super().test_update_large()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; TypeError: a bytes-like object is required, not 'NoneType'
-    def test_update_exceptions(self):
-        return super().test_update_exceptions()
-
 
 class BuiltinUpdateTestCase(BuiltinModuleMixin,
                             UpdateTestCaseMixin, unittest.TestCase):
@@ -1320,7 +1300,6 @@ def test_realcopy(self):
         self.assertNotEqual(id(h1._inner), id(h2._inner))
         self.assertNotEqual(id(h1._outer), id(h2._outer))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; TypeError: a bytes-like object is required, not 'NoneType'
     def test_equality(self):
         # Testing if the copy has the same digests.
         h1 = hmac.HMAC(b"key", digestmod="sha256")
@@ -1329,7 +1308,6 @@ def test_equality(self):
         self.assertEqual(h1.digest(), h2.digest())
         self.assertEqual(h1.hexdigest(), h2.hexdigest())
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; TypeError: a bytes-like object is required, not 'NoneType'
     def test_equality_new(self):
         # Testing if the copy has the same digests with hmac.new().
         h1 = hmac.new(b"key", digestmod="sha256")
@@ -1375,14 +1353,6 @@ class OpenSSLCopyTestCase(ExtensionCopyTestCase, unittest.TestCase):
     def init(self, h):
         h._init_openssl_hmac(b"key", b"msg", digestmod="sha256")
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; _hashlib.UnsupportedDigestmodError: unsupported hash type
-    def test_attributes(self):
-        return super().test_attributes()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; _hashlib.UnsupportedDigestmodError: unsupported hash type
-    def test_realcopy(self):
-        return super().test_realcopy()
-
 
 @hashlib_helper.requires_builtin_hmac()
 class BuiltinCopyTestCase(ExtensionCopyTestCase, unittest.TestCase):

diff --git a/crates/stdlib/src/hashlib.rs b/crates/stdlib/src/hashlib.rs
@@ -19,7 +19,7 @@ pub mod _hashlib {
         types::{Constructor, Representable},
     };
     use blake2::{Blake2b512, Blake2s256};
-    use digest::{DynDigest, core_api::BlockSizeUser};
+    use digest::{DynDigest, OutputSizeUser, core_api::BlockSizeUser};
     use digest::{ExtendableOutput, Update};
     use dyn_clone::{DynClone, clone_trait_object};
     use hmac::Mac;
@@ -258,6 +258,105 @@ pub mod _hashlib {
         )
     }
 
+    // Object-safe HMAC trait for type-erased dispatch
+    trait DynHmac: Send + Sync {
+        fn dyn_update(&mut self, data: &[u8]);
+        fn dyn_finalize(&self) -> Vec<u8>;
+        fn dyn_clone(&self) -> Box<dyn DynHmac>;
+    }
+
+    struct TypedHmac<D>(D);
+
+    impl<D> DynHmac for TypedHmac<D>
+    where
+        D: Mac + Clone + Send + Sync + 'static,
+    {
+        fn dyn_update(&mut self, data: &[u8]) {
+            Mac::update(&mut self.0, data);
+        }
+
+        fn dyn_finalize(&self) -> Vec<u8> {
+            self.0.clone().finalize().into_bytes().to_vec()
+        }
+
+        fn dyn_clone(&self) -> Box<dyn DynHmac> {
+            Box::new(TypedHmac(self.0.clone()))
+        }
+    }
+
+    #[pyattr]
+    #[pyclass(module = "_hashlib", name = "HMAC")]
+    #[derive(PyPayload)]
+    pub struct PyHmac {
+        algo_name: String,
+        digest_size: usize,
+        block_size: usize,
+        ctx: PyRwLock<Box<dyn DynHmac>>,
+    }
+
+    impl core::fmt::Debug for PyHmac {
+        fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+            write!(f, "HMAC {}", self.algo_name)
+        }
+    }
+
+    #[pyclass(with(Representable), flags(IMMUTABLETYPE))]
+    impl PyHmac {
+        #[pyslot]
+        fn slot_new(_cls: PyTypeRef, _args: FuncArgs, vm: &VirtualMachine) -> PyResult {
+            Err(vm.new_type_error("cannot create '_hashlib.HMAC' instances".to_owned()))
+        }
+
+        #[pygetset]
+        fn name(&self) -> String {
+            format!("hmac-{}", self.algo_name)
+        }
+
+        #[pygetset]
+        fn digest_size(&self) -> usize {
+            self.digest_size
+        }
+
+        #[pygetset]
+        fn block_size(&self) -> usize {
+            self.block_size
+        }
+
+        #[pymethod]
+        fn update(&self, msg: ArgBytesLike) {
+            msg.with_ref(|bytes| self.ctx.write().dyn_update(bytes));
+        }
+
+        #[pymethod]
+        fn digest(&self) -> PyBytes {
+            self.ctx.read().dyn_finalize().into()
+        }
+
+        #[pymethod]
+        fn hexdigest(&self) -> String {
+            hex::encode(self.ctx.read().dyn_finalize())
+        }
+
+        #[pymethod]
+        fn copy(&self) -> Self {
+            Self {
+                algo_name: self.algo_name.clone(),
+                digest_size: self.digest_size,
+                block_size: self.block_size,
+                ctx: PyRwLock::new(self.ctx.read().dyn_clone()),
+            }
+        }
+    }
+
+    impl Representable for PyHmac {
+        fn repr_str(zelf: &Py<Self>, _vm: &VirtualMachine) -> PyResult<String> {
+            Ok(format!(
+                "<{} HMAC object @ {:#x}>",
+                zelf.algo_name, zelf as *const _ as usize
+            ))
+        }
+    }
+
     #[pyattr]
     #[pyclass(module = "_hashlib", name = "HASH")]
     #[derive(PyPayload)]
@@ -646,18 +745,50 @@ pub mod _hashlib {
         #[pyarg(positional)]
         key: ArgBytesLike,
         #[pyarg(any, optional)]
-        msg: OptionalArg<ArgBytesLike>,
+        msg: OptionalArg<Option<ArgBytesLike>>,
         #[pyarg(named, optional)]
         digestmod: OptionalArg<PyObjectRef>,
     }
 
     #[pyfunction]
-    fn hmac_new(args: NewHMACHashArgs, vm: &VirtualMachine) -> PyResult<PyObjectRef> {
-        let _ = args;
-        Err(vm.new_exception_msg(
-            UnsupportedDigestmodError::static_type().to_owned(),
-            "unsupported hash type".to_owned(),
-        ))
+    fn hmac_new(args: NewHMACHashArgs, vm: &VirtualMachine) -> PyResult<PyHmac> {
+        let digestmod = args.digestmod.into_option().ok_or_else(|| {
+            vm.new_type_error("Missing required parameter 'digestmod'.".to_owned())
+        })?;
+        let name = resolve_digestmod(&digestmod, vm)?;
+
+        let key_buf = args.key.borrow_buf();
+        let msg_data = args.msg.flatten();
+
+        macro_rules! make_hmac {
+            ($hash_ty:ty) => {{
+                let mut mac = <hmac::Hmac<$hash_ty> as Mac>::new_from_slice(&key_buf)
+                    .map_err(|_| vm.new_value_error("invalid key length".to_owned()))?;
+                if let Some(ref m) = msg_data {
+                    m.with_ref(|bytes| Mac::update(&mut mac, bytes));
+                }
+                Ok(PyHmac {
+                    algo_name: name,
+                    digest_size: <$hash_ty as OutputSizeUser>::output_size(),
+                    block_size: <$hash_ty as BlockSizeUser>::block_size(),
+                    ctx: PyRwLock::new(Box::new(TypedHmac(mac))),
+                })
+            }};
+        }
+
+        match name.as_str() {
+            "md5" => make_hmac!(Md5),
+            "sha1" => make_hmac!(Sha1),
+            "sha224" => make_hmac!(Sha224),
+            "sha256" => make_hmac!(Sha256),
+            "sha384" => make_hmac!(Sha384),
+            "sha512" => make_hmac!(Sha512),
+            "sha3_224" => make_hmac!(Sha3_224),
+            "sha3_256" => make_hmac!(Sha3_256),
+            "sha3_384" => make_hmac!(Sha3_384),
+            "sha3_512" => make_hmac!(Sha3_512),
+            _ => Err(unsupported_hash(&name, vm)),
+        }
     }
 
     #[pyfunction]