From 0c1bf69e13e98ebdce4c49fac08c668c7823c5fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Sun, 9 Aug 2026 14:42:20 +0200
Subject: [PATCH 1/2] gh-155426: correctly accept bytes-like keys in
 `hmac.digest`

This only affects keys of length smaller than the HMAC blocksize
since larger keys are hashed first.
---
 Lib/hmac.py                                                 | 3 +++
 Lib/test/test_hmac.py                                       | 6 ++++++
 .../Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst  | 3 +++
 3 files changed, 12 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst

diff --git a/Lib/hmac.py b/Lib/hmac.py
index e0c040bcd5fe3d2..61e0823e68be215 100644
--- a/Lib/hmac.py
+++ b/Lib/hmac.py
@@ -267,6 +267,9 @@ def digest(key, msg, digest):
 
 
 def _compute_digest_fallback(key, msg, digest):
+    if not isinstance(key, (bytes, bytearray)):
+        raise TypeError(f"key: expected bytes or bytearray, "
+                        f"but got {type(key).__name__!r}")
     digest_cons = _get_digest_constructor(digest)
     if _is_shake_constructor(digest_cons):
         raise ValueError(f"unsupported hash algorithm {digest}")
diff --git a/Lib/test/test_hmac.py b/Lib/test/test_hmac.py
index 1ea182fec4ff189..6d3a14eb25543ed 100644
--- a/Lib/test/test_hmac.py
+++ b/Lib/test/test_hmac.py
@@ -1519,6 +1519,12 @@ def test_with_fallback(self):
         finally:
             cache.pop('foo')
 
+    @hashlib_helper.requires_hashdigest("md5")
+    def test_hmac_digest_reject_memoryview_for_key(self):
+        hmac = import_fresh_module("hmac", blocked=["_hashlib", "_hmac"])
+        with self.assertRaises(TypeError):
+            hmac.digest(memoryview(b"small"), b"world", "md5")
+
     @hashlib_helper.requires_openssl_hashdigest("md5")
     @bigmemtest(size=_4G + 5, memuse=2, dry_run=False)
     def test_hmac_digest_overflow_error_openssl_only(self, size):
diff --git a/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst b/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst
new file mode 100644
index 000000000000000..52878bf104f6a5f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst
@@ -0,0 +1,3 @@
+Make sure that the pure Python fallback of :func:`hmac.digest` reject
+keys that are neither :class:`bytes` or :class:`bytearray`. Patch by
+Bénédikt Tran.

From cacd82433bb059a02d3a1710934e1003124d83fe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C3=A9n=C3=A9dikt=20Tran?=
 <10796600+picnixz@users.noreply.github.com>
Date: Sun, 9 Aug 2026 17:50:56 +0200
Subject: [PATCH 2/2] Update
 Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst

---
 .../Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst   | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst b/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst
index 52878bf104f6a5f..f1839defbe56742 100644
--- a/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst
+++ b/Misc/NEWS.d/next/Library/2026-08-09-14-06-27.gh-issue-155426.zZVPMd.rst
@@ -1,3 +1,4 @@
 Make sure that the pure Python fallback of :func:`hmac.digest` reject
-keys that are neither :class:`bytes` or :class:`bytearray`. Patch by
-Bénédikt Tran.
+keys that are neither :class:`bytes` or :class:`bytearray`. Previously,
+an :exc:`AttributeError` was raised instead of :exc:`TypeError`.
+Patch by Bénédikt Tran.