diff --git a/hooks/playbooks/ceph.yml b/hooks/playbooks/ceph.yml
index 945be9f1f..13f5ce610 100644
--- a/hooks/playbooks/ceph.yml
+++ b/hooks/playbooks/ceph.yml
@@ -353,6 +353,7 @@
 
     - name: Generate a cephx key
       cephx_key:
+        cipher: "{{ cifmw_ceph_key_cipher | default('aes') }}"
       register: cephx
       no_log: "{{ cifmw_nolog | default(true) | bool }}"
 
diff --git a/plugins/modules/cephx_key.py b/plugins/modules/cephx_key.py
index d84cff29e..da7f5946b 100644
--- a/plugins/modules/cephx_key.py
+++ b/plugins/modules/cephx_key.py
@@ -14,17 +14,38 @@
 short_description: Generate a random CephX authentication key
 
 description:
-- Generate a random CephX authentication key and return it
+- Generate a random CephX authentication key and return it.
+- Supports AES-128 (default, type=1, 16-byte key) and AES-256k (type=2, 32-byte key) ciphers.
+
+options:
+  cipher:
+    description:
+      - The cipher to use when generating the CephX key.
+      - Use C(aes) for AES-128 (16-byte key, 40-char base64, type=1). This is the default.
+      - Use C(aes256k) for AES-256k (32-byte key, 60-char base64, type=2).
+    type: str
+    default: aes
+    choices: [aes, aes256k]
 
 author:
   - John Fulton (@fultonj)
 """
 
 EXAMPLES = r"""
-- name: Generate a cephx key
+- name: Generate a cephx key (AES-128, backward compatible default)
   cifmw.general.cephx_key:
   register: cephx
 
+- name: Generate a cephx key with explicit AES-128 cipher
+  cifmw.general.cephx_key:
+    cipher: aes
+  register: cephx
+
+- name: Generate a cephx key with AES-256k cipher
+  cifmw.general.cephx_key:
+    cipher: aes256k
+  register: cephx
+
 - name: Show cephx key
   debug:
     msg: "{{ cephx.key }}"
@@ -32,11 +53,14 @@
 
 RETURN = r"""
 key:
-    description: A random cephx authentication key
-    type: dict
+    description:
+      - A random CephX authentication key encoded as base64.
+      - AES-128 keys are 40 characters long (ending with ==).
+      - AES-256k keys are 60 characters long (ending with =).
+    type: str
     returned: success
     sample:
-        - KEY: AQC+vYNXgDAgAhAAc8UoYt+OTz5uhV7ItLdwUw==
+        - AQC+vYNXgDAgAhAAc8UoYt+OTz5uhV7ItLdwUw==
 """
 
 
@@ -47,21 +71,33 @@
 import time
 
 
-def __create_cephx_key():
+def __create_cephx_key(cipher="aes"):
     # NOTE(fultonj): Taken from
     # https://github.com/ceph/ceph-deploy/blob/master/ceph_deploy/new.py#L21
-    key = os.urandom(16)
-    header = struct.pack("<hiih", 1, int(time.time()), 0, len(key))
+    if cipher == "aes256k":
+        key_type = 2
+        key = os.urandom(32)
+    else:
+        key_type = 1
+        key = os.urandom(16)
+    header = struct.pack("<hiih", key_type, int(time.time()), 0, len(key))
     return base64.b64encode(header + key).decode("utf-8")
 
 
 def main():
-    mod_args = {}
+    mod_args = {
+        "cipher": {
+            "type": "str",
+            "default": "aes",
+            "choices": ["aes", "aes256k"],
+        }
+    }
     module = AnsibleModule(argument_spec=mod_args, supports_check_mode=False)
 
     result = {"changed": False, "error": ""}
 
-    cephx_key = __create_cephx_key()
+    cipher = module.params["cipher"]
+    cephx_key = __create_cephx_key(cipher)
     if not cephx_key:
         result["msg"] = "Error: unable to create cephx key"
         module.fail_json(**result)
diff --git a/tests/unit/modules/test_cephx_key.py b/tests/unit/modules/test_cephx_key.py
new file mode 100644
index 000000000..b10be2211
--- /dev/null
+++ b/tests/unit/modules/test_cephx_key.py
@@ -0,0 +1,136 @@
+# Copyright: (c) 2026, Red Hat
+
+# GNU General Public License v3.0+ (see COPYING or
+# https://www.gnu.org/licenses/gpl-3.0.txt)
+from __future__ import absolute_import, division, print_function
+
+import base64
+import struct
+import unittest.mock  # noqa: F401 — required so unittest.mock is loaded for utils.py setUp
+
+from ansible_collections.cifmw.general.tests.unit.utils import (
+    AnsibleExitJson,
+    AnsibleFailJson,
+    ModuleBaseTestCase,
+    set_module_args,
+)
+from ansible_collections.cifmw.general.plugins.modules import cephx_key
+
+
+class TestCephxKey(ModuleBaseTestCase):
+    """Unit tests for the cephx_key Ansible module."""
+
+    def _decode_key(self, key_b64):
+        """Decode a base64 CephX key and return (header_tuple, key_bytes)."""
+        raw = base64.b64decode(key_b64)
+        # Header is 12 bytes: struct.pack("<hiih", type, sec, nsec, key_len)
+        header = struct.unpack("<hiih", raw[:12])
+        key_bytes = raw[12:]
+        return header, key_bytes
+
+    def test_default_cipher_returns_aes128_key(self):
+        """No args: default cipher produces a 28-byte (AES-128) encoded key."""
+        set_module_args({})
+        with self.assertRaises(AnsibleExitJson) as ctx:
+            cephx_key.main()
+        result = ctx.exception.args[0]
+        self.assertIn("key", result)
+        key_b64 = result["key"]
+        raw = base64.b64decode(key_b64)
+        self.assertEqual(len(raw), 28)
+        header, key_bytes = self._decode_key(key_b64)
+        # type=1, key_len=16
+        self.assertEqual(header[0], 1)
+        self.assertEqual(header[3], 16)
+        self.assertEqual(len(key_bytes), 16)
+
+    def test_aes_cipher_returns_aes128_key(self):
+        """cipher=aes produces a 28-byte (AES-128) encoded key."""
+        set_module_args({"cipher": "aes"})
+        with self.assertRaises(AnsibleExitJson) as ctx:
+            cephx_key.main()
+        result = ctx.exception.args[0]
+        key_b64 = result["key"]
+        raw = base64.b64decode(key_b64)
+        self.assertEqual(len(raw), 28)
+        header, key_bytes = self._decode_key(key_b64)
+        self.assertEqual(header[0], 1)
+        self.assertEqual(header[3], 16)
+        self.assertEqual(len(key_bytes), 16)
+
+    def test_aes256k_cipher_returns_aes256k_key(self):
+        """cipher=aes256k produces a 44-byte (AES-256k) encoded key."""
+        set_module_args({"cipher": "aes256k"})
+        with self.assertRaises(AnsibleExitJson) as ctx:
+            cephx_key.main()
+        result = ctx.exception.args[0]
+        key_b64 = result["key"]
+        raw = base64.b64decode(key_b64)
+        self.assertEqual(len(raw), 44)
+        header, key_bytes = self._decode_key(key_b64)
+        # type=2, key_len=32
+        self.assertEqual(header[0], 2)
+        self.assertEqual(header[3], 32)
+        self.assertEqual(len(key_bytes), 32)
+
+    def test_invalid_cipher_fails(self):
+        """cipher=invalid raises AnsibleFailJson (AnsibleModule enforces choices)."""
+        set_module_args({"cipher": "invalid"})
+        with self.assertRaises(AnsibleFailJson) as ctx:
+            cephx_key.main()
+        result = ctx.exception.args[0]
+        self.assertTrue(result["failed"])
+
+    def test_aes_key_is_valid_base64(self):
+        """AES-128 key is valid base64 and ends with ==."""
+        set_module_args({"cipher": "aes"})
+        with self.assertRaises(AnsibleExitJson) as ctx:
+            cephx_key.main()
+        key_b64 = ctx.exception.args[0]["key"]
+        # Should not raise
+        decoded = base64.b64decode(key_b64)
+        self.assertIsInstance(decoded, bytes)
+        self.assertTrue(
+            key_b64.endswith("=="), f"Expected == suffix, got: {key_b64[-2:]}"
+        )
+
+    def test_aes256k_key_is_valid_base64(self):
+        """AES-256k key is valid base64 and ends with a single =."""
+        set_module_args({"cipher": "aes256k"})
+        with self.assertRaises(AnsibleExitJson) as ctx:
+            cephx_key.main()
+        key_b64 = ctx.exception.args[0]["key"]
+        decoded = base64.b64decode(key_b64)
+        self.assertIsInstance(decoded, bytes)
+        self.assertTrue(
+            key_b64.endswith("=") and not key_b64.endswith("=="),
+            f"Expected single = suffix, got: {key_b64[-2:]}",
+        )
+
+    def test_key_changes_on_each_call(self):
+        """Two successive calls produce different keys (randomness check)."""
+        set_module_args({"cipher": "aes"})
+        with self.assertRaises(AnsibleExitJson) as ctx1:
+            cephx_key.main()
+        key1 = ctx1.exception.args[0]["key"]
+
+        set_module_args({"cipher": "aes"})
+        with self.assertRaises(AnsibleExitJson) as ctx2:
+            cephx_key.main()
+        key2 = ctx2.exception.args[0]["key"]
+
+        self.assertNotEqual(key1, key2)
+
+    def test_aes256k_key_changes_on_each_call(self):
+        """Two successive aes256k calls produce different keys (randomness check)."""
+        set_module_args({"cipher": "aes256k"})
+        with self.assertRaises(AnsibleExitJson) as ctx1:
+            cephx_key.main()
+        key1 = ctx1.exception.args[0]["key"]
+
+        set_module_args({"cipher": "aes256k"})
+        with self.assertRaises(AnsibleExitJson) as ctx2:
+            cephx_key.main()
+        key2 = ctx2.exception.args[0]["key"]
+
+        self.assertNotEqual(key1, key2)