diff --git a/rust/src/e2e_keys/mod.rs b/rust/src/e2e_keys/mod.rs
new file mode 100644
index 0000000000..f5c7dd1e38
--- /dev/null
+++ b/rust/src/e2e_keys/mod.rs
@@ -0,0 +1,83 @@
+/*
+ * This file is licensed under the Affero General Public License (AGPL) version 3.
+ *
+ * Copyright (C) 2026 Element Creations Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * See the GNU Affero General Public License for more details:
+ * <https://www.gnu.org/licenses/agpl-3.0.html>.
+ *
+ * Originally licensed under the Apache License, Version 2.0:
+ * <http://www.apache.org/licenses/LICENSE-2.0>.
+ *
+ * [This file includes modifications made by Element Creations Ltd]
+ */
+
+use pyo3::{
+    pyclass, pymethods,
+    types::{PyAnyMethods, PyModule, PyModuleMethods},
+    Bound, Py, PyAny, PyResult, Python,
+};
+
+pub fn register_module(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
+    let child_module = PyModule::new(py, "e2e_keys")?;
+    child_module.add_class::<SignatureListItem>()?;
+
+    m.add_submodule(&child_module)?;
+
+    py.import("sys")?
+        .getattr("modules")?
+        .set_item("synapse.synapse_rust.e2e_keys", child_module)?;
+
+    Ok(())
+}
+
+/// A pending cross-signing signature.
+#[derive(Debug)]
+#[pyclass(frozen)]
+pub struct SignatureListItem {
+    /// Full key ID of the signing key, e.g. `"ed25519:ABCDEF"`.
+    #[pyo3(get)]
+    pub signing_key_id: String,
+
+    /// User whose key was signed.
+    #[pyo3(get)]
+    pub target_user_id: String,
+
+    /// Device ID (or master-key ID) that the signature targets.
+    #[pyo3(get)]
+    pub target_device_id: String,
+
+    /// Raw signature value.
+    #[pyo3(get)]
+    pub signature: Py<PyAny>,
+}
+
+#[pymethods]
+impl SignatureListItem {
+    #[new]
+    fn py_new(
+        signing_key_id: String,
+        target_user_id: String,
+        target_device_id: String,
+        signature: Py<PyAny>,
+    ) -> Self {
+        Self {
+            signing_key_id,
+            target_user_id,
+            target_device_id,
+            signature,
+        }
+    }
+
+    fn __repr__(&self) -> String {
+        format!(
+            "SignatureListItem(signing_key_id={:?}, target_user_id={:?}, target_device_id={:?})",
+            self.signing_key_id, self.target_user_id, self.target_device_id,
+        )
+    }
+}
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index cc89862e4e..c809b65418 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -7,6 +7,7 @@ use pyo3_log::ResetHandle;
 pub mod acl;
 pub mod canonical_json;
 pub mod duration;
+pub mod e2e_keys;
 pub mod errors;
 pub mod events;
 pub mod http;
@@ -64,6 +65,7 @@ fn synapse_rust(py: Python<'_>, m: &Bound<'_, PyModule>) -> PyResult<()> {
 
     acl::register_module(py, m)?;
     push::register_module(py, m)?;
+    e2e_keys::register_module(py, m)?;
     events::register_module(py, m)?;
     http_client::register_module(py, m)?;
     rendezvous::register_module(py, m)?;
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 64f705a3da..b67c2ca985 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -22,7 +22,6 @@
 import logging
 from typing import TYPE_CHECKING, Iterable, Mapping
 
-import attr
 from canonicaljson import encode_canonical_json
 from signedjson.key import VerifyKey, decode_verify_key_bytes
 from signedjson.sign import SignatureVerifyException, verify_signed_json
@@ -35,6 +34,7 @@ from synapse.api.errors import CodeMessageException, Codes, NotFoundError, Synap
 from synapse.handlers.device import DeviceWriterHandler
 from synapse.logging.context import make_deferred_yieldable, run_in_background
 from synapse.logging.opentracing import log_kv, set_tag, tag_args, trace
+from synapse.synapse_rust.e2e_keys import SignatureListItem
 from synapse.types import (
     JsonDict,
     JsonMapping,
@@ -1132,7 +1132,7 @@ class E2eKeysHandler:
 
     async def _process_self_signatures(
         self, user_id: str, signatures: JsonDict
-    ) -> tuple[list["SignatureListItem"], dict[str, dict[str, dict]]]:
+    ) -> tuple[list[SignatureListItem], dict[str, dict[str, dict]]]:
         """Process uploaded signatures of the user's own keys.
 
         Signatures of the user's own keys from this API come in two forms:
@@ -1150,7 +1150,7 @@ class E2eKeysHandler:
         Raises:
             SynapseError: if the input is malformed
         """
-        signature_list: list["SignatureListItem"] = []
+        signature_list: list[SignatureListItem] = []
         failures: dict[str, dict[str, JsonDict]] = {}
         if not signatures:
             return signature_list, failures
@@ -1252,7 +1252,7 @@ class E2eKeysHandler:
         signed_master_key: JsonDict,
         stored_master_key: JsonMapping,
         devices: dict[str, dict[str, JsonDict]],
-    ) -> list["SignatureListItem"]:
+    ) -> list[SignatureListItem]:
         """Check signatures of a user's master key made by their devices.
 
         Args:
@@ -1296,7 +1296,7 @@ class E2eKeysHandler:
 
     async def _process_other_signatures(
         self, user_id: str, signatures: dict[str, dict]
-    ) -> tuple[list["SignatureListItem"], dict[str, dict[str, dict]]]:
+    ) -> tuple[list[SignatureListItem], dict[str, dict[str, dict]]]:
         """Process uploaded signatures of other users' keys.  These will be the
         target user's master keys, signed by the uploading user's user-signing
         key.
@@ -1312,7 +1312,7 @@ class E2eKeysHandler:
         Raises:
             SynapseError: if the input is malformed
         """
-        signature_list: list["SignatureListItem"] = []
+        signature_list: list[SignatureListItem] = []
         failures: dict[str, dict[str, JsonDict]] = {}
         if not signatures:
             return signature_list, failures
@@ -1747,16 +1747,6 @@ def _one_time_keys_match(old_key_json: str, new_key: JsonDict) -> bool:
     return old_key == new_key_copy
 
 
-@attr.s(slots=True, auto_attribs=True)
-class SignatureListItem:
-    """An item in the signature list as used by upload_signatures_for_device_keys."""
-
-    signing_key_id: str
-    target_user_id: str
-    target_device_id: str
-    signature: JsonDict
-
-
 class SigningKeyEduUpdater:
     """Handles incoming signing key updates from federation and updates the DB"""
 
diff --git a/synapse/storage/databases/main/end_to_end_keys.py b/synapse/storage/databases/main/end_to_end_keys.py
index c93ebd3dda..000cfca6c2 100644
--- a/synapse/storage/databases/main/end_to_end_keys.py
+++ b/synapse/storage/databases/main/end_to_end_keys.py
@@ -61,8 +61,8 @@ from synapse.util.iterutils import batch_iter
 from synapse.util.json import json_decoder, json_encoder
 
 if TYPE_CHECKING:
-    from synapse.handlers.e2e_keys import SignatureListItem
     from synapse.server import HomeServer
+    from synapse.synapse_rust.e2e_keys import SignatureListItem
 
 
 @attr.s(slots=True, auto_attribs=True)
diff --git a/synapse/synapse_rust/e2e_keys.pyi b/synapse/synapse_rust/e2e_keys.pyi
new file mode 100644
index 0000000000..07d3513f4d
--- /dev/null
+++ b/synapse/synapse_rust/e2e_keys.pyi
@@ -0,0 +1,24 @@
+from typing import Any
+
+class SignatureListItem:
+    """A pending cross-signing signature."""
+
+    signing_key_id: str
+    """ Full key ID of the signing key, e.g. `"ed25519:ABCDEF"`."""
+
+    target_user_id: str
+    """User whose key was signed."""
+
+    target_device_id: str
+    """Device ID (or master-key ID) that the signature targets."""
+
+    signature: Any
+    """Raw signature value."""
+
+    def __init__(
+        self,
+        signing_key_id: str,
+        target_user_id: str,
+        target_device_id: str,
+        signature: Any,
+    ) -> None: ...