diff --git a/src/requests/auth.py b/src/requests/auth.py
index 4a7ce6dc14..da086f6d4a 100644
--- a/src/requests/auth.py
+++ b/src/requests/auth.py
@@ -123,6 +123,45 @@ def init_per_thread_state(self):
             self._thread_local.pos = None
             self._thread_local.num_401_calls = None
 
+    @staticmethod
+    def _encode_data(data, codec="latin-1"):
+        """
+        This function encodes input data to bytes using the specified
+        encoding (default is Latin-1). It returns the encoded data as bytes.
+        :rtype: tuple[bytes, Optional[str]]
+        """
+        if type(data) is bytes:
+            return data, None
+        try:
+            return str(data).encode(codec), codec
+        except UnicodeEncodeError:
+            warnings.warn(
+                "This data will be encoded with UTF-8 because the provided "
+                "encoding could not handle some characters.",
+                category=UnicodeWarning,
+            )
+            if codec != "utf-8":
+                return HTTPDigestAuth._encode_data(data, "utf-8")
+            else:
+                raise UnicodeEncodeError("Cannot encode the provided data...")
+
+    @staticmethod
+    def _decode_data(data, codec):
+        """
+        This function decodes input data from bytes using the specified
+        encoding. It returns the decoded data as a string.
+        :rtype: str
+        """
+        if type(data) is not bytes:
+            return data
+        if codec is None:
+            warnings.warn(
+                "No encoding provided. The data will be decoded using UTF-8.",
+                category=UnicodeWarning,
+            )
+            codec = "utf-8"
+        return data.decode(codec)
+
     def build_digest_header(self, method, url):
         """
         :rtype: str
@@ -186,7 +225,11 @@ def sha512_utf8(x):
         if p_parsed.query:
             path += f"?{p_parsed.query}"
 
-        A1 = f"{self.username}:{realm}:{self.password}"
+        username, username_codec = self._encode_data(self.username)
+        realm, realm_codec = self._encode_data(realm)
+        password, _ = self._encode_data(self.password)
+
+        A1 = b":".join([username, realm, password])
         A2 = f"{method}:{path}"
 
         HA1 = hash_utf8(A1)
@@ -218,9 +261,11 @@ def sha512_utf8(x):
         self._thread_local.last_nonce = nonce
 
         # XXX should the partial digests be encoded too?
+        decoded_username = self._decode_data(username, username_codec)
+        decoded_realm = self._decode_data(realm, realm_codec)
         base = (
-            f'username="{self.username}", realm="{realm}", nonce="{nonce}", '
-            f'uri="{path}", response="{respdig}"'
+            f'username="{decoded_username}", realm="{decoded_realm}", '
+            f'nonce="{nonce}", uri="{path}", response="{respdig}"'
         )
         if opaque:
             base += f', opaque="{opaque}"'
diff --git a/tests/test_auth.py b/tests/test_auth.py
new file mode 100644
index 0000000000..a0328e7f31
--- /dev/null
+++ b/tests/test_auth.py
@@ -0,0 +1,27 @@
+import pytest
+
+# from requests.auth import HTTPDigestAuth
+from src.requests.auth import HTTPDigestAuth
+
+
+class TestDigestAuth:
+    def _build_a_digest_auth(self, user, password):
+        auth = HTTPDigestAuth(user, password)
+        auth.init_per_thread_state()
+        auth._thread_local.chal["realm"] = "eggs"
+        auth._thread_local.chal["nonce"] = "chips"
+        return auth.build_digest_header("GET", "https://www.example.com/")
+
+    @pytest.mark.parametrize(
+        "username, password",
+        (
+            ("spam", "ham"),
+            ("имя", "пароль"),
+        ),
+    )
+    def test_digestauth_encode_consistency(self, username, password):
+        auth = username, password
+        str_auth = self._build_a_digest_auth(*auth)
+        bauth = username.encode("utf-8"), password.encode("utf-8")
+        bin_auth = self._build_a_digest_auth(*bauth)
+        assert str_auth == bin_auth