From 83288d6c41c9d0dd6bdbbeab619525f7c18fc49f Mon Sep 17 00:00:00 2001
From: akiyuki ishikawa <aki.y.ishikawa@gmail.com>
Date: Wed, 16 Jun 2021 12:47:26 +0900
Subject: [PATCH 1/3] Fix hash_pandas_object does not recognize hash_key

---
 pandas/core/util/hashing.py       |  5 ++++-
 pandas/tests/util/test_hashing.py | 10 ++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/pandas/core/util/hashing.py b/pandas/core/util/hashing.py
index 962728b2f38c4..09213b9e37aa2 100644
--- a/pandas/core/util/hashing.py
+++ b/pandas/core/util/hashing.py
@@ -139,7 +139,10 @@ def hash_pandas_object(
         ser = Series(h, index=obj.index, dtype="uint64", copy=False)
 
     elif isinstance(obj, ABCDataFrame):
-        hashes = (hash_array(series._values) for _, series in obj.items())
+        hashes = (
+            hash_array(series._values, encoding, hash_key, categorize)
+            for _, series in obj.items()
+        )
         num_items = len(obj.columns)
         if index:
             index_hash_generator = (
diff --git a/pandas/tests/util/test_hashing.py b/pandas/tests/util/test_hashing.py
index 8ce24dc963dc5..1567deca93eca 100644
--- a/pandas/tests/util/test_hashing.py
+++ b/pandas/tests/util/test_hashing.py
@@ -255,6 +255,16 @@ def test_hash_keys():
     assert (a != b).all()
 
 
+def test_df_hash_keys():
+    # DataFrame version of the test_hash_keys
+    obj = DataFrame({"x": np.arange(3), "y": list("abc")})
+
+    a = hash_pandas_object(obj, hash_key="9876543210123456")
+    b = hash_pandas_object(obj, hash_key="9876543210123465")
+
+    assert (a != b).all()
+
+
 def test_invalid_key():
     # This only matters for object dtypes.
     msg = "key should be a 16-byte string encoded"

From 6b797deb95d2edd2a4d02efb4f4c3b8930ce3654 Mon Sep 17 00:00:00 2001
From: akiyuki ishikawa <aki.y.ishikawa@gmail.com>
Date: Thu, 17 Jun 2021 12:04:30 +0900
Subject: [PATCH 2/3] Add encoding test case and links to issues

---
 pandas/tests/util/test_hashing.py | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/util/test_hashing.py b/pandas/tests/util/test_hashing.py
index 1567deca93eca..e4a46de11ceb7 100644
--- a/pandas/tests/util/test_hashing.py
+++ b/pandas/tests/util/test_hashing.py
@@ -256,7 +256,8 @@ def test_hash_keys():
 
 
 def test_df_hash_keys():
-    # DataFrame version of the test_hash_keys
+    # DataFrame version of the test_hash_keys.
+    # https://github.com/pandas-dev/pandas/issues/41404
     obj = DataFrame({"x": np.arange(3), "y": list("abc")})
 
     a = hash_pandas_object(obj, hash_key="9876543210123456")
@@ -265,6 +266,21 @@ def test_df_hash_keys():
     assert (a != b).all()
 
 
+def test_df_encoding():
+    # Check that DataFrame recognizes optional encoding.
+    # https://github.com/pandas-dev/pandas/issues/41404
+    # https://github.com/pandas-dev/pandas/pull/42049
+    obj = DataFrame({"x": np.arange(3), "y": list("a+c")})
+
+    a = hash_pandas_object(obj, encoding="utf8")
+    b = hash_pandas_object(obj, encoding="utf7")
+
+    # Note that the "+" is encoded as "+-" in utf-7.
+    assert a[0] == b[0]
+    assert a[1] != b[1]
+    assert a[2] == b[2]
+
+
 def test_invalid_key():
     # This only matters for object dtypes.
     msg = "key should be a 16-byte string encoded"

From ceb689dc30d8df751cc8e769c085534f3badede8 Mon Sep 17 00:00:00 2001
From: akiyuki ishikawa <aki.y.ishikawa@gmail.com>
Date: Fri, 18 Jun 2021 09:27:19 +0900
Subject: [PATCH 3/3] Added whatsnew entry.

---
 doc/source/whatsnew/v1.3.0.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/source/whatsnew/v1.3.0.rst b/doc/source/whatsnew/v1.3.0.rst
index 438313f3e58e2..7269a184358b7 100644
--- a/doc/source/whatsnew/v1.3.0.rst
+++ b/doc/source/whatsnew/v1.3.0.rst
@@ -1205,6 +1205,7 @@ Other
 - Bug in :class:`Series` backed by :class:`DatetimeArray` or :class:`TimedeltaArray` sometimes failing to set the array's ``freq`` to ``None`` (:issue:`41425`)
 - Bug in creating a :class:`Series` from a ``range`` object that does not fit in the bounds of ``int64`` dtype (:issue:`30173`)
 - Bug in creating a :class:`Series` from a ``dict`` with all-tuple keys and an :class:`Index` that requires reindexing (:issue:`41707`)
+- Bug in :func:`pandas.util.hash_pandas_object` not recognizing ``hash_key``, ``encoding`` and ``categorize`` when the input object type is a :class:`DataFrame` (:issue:`41404`)
 
 .. ---------------------------------------------------------------------------