From 8a631e7c29d2ee795376ff5b4fb4953793483b5f Mon Sep 17 00:00:00 2001
From: Dakota Brink <779390+codabrink@users.noreply.github.com>
Date: Tue, 17 Dec 2024 10:43:18 -0500
Subject: [PATCH] Cycle the HMAC key on installation revoke (#1427)

* cycle the hmac key on revoke and test

* use the wasm trait
---
 xmtp_mls/src/groups/device_sync/preference_sync.rs | 9 +++++++++
 xmtp_mls/src/identity_updates.rs                   | 8 +++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/xmtp_mls/src/groups/device_sync/preference_sync.rs b/xmtp_mls/src/groups/device_sync/preference_sync.rs
index 9f23374b1..f6028d64d 100644
--- a/xmtp_mls/src/groups/device_sync/preference_sync.rs
+++ b/xmtp_mls/src/groups/device_sync/preference_sync.rs
@@ -93,6 +93,7 @@ mod tests {
     use super::*;
     use crate::{
         builder::ClientBuilder,
+        groups::scoped_client::ScopedGroupClient,
         storage::consent_record::{ConsentState, ConsentType},
     };
     use crypto_utils::generate_local_wallet;
@@ -158,5 +159,13 @@ mod tests {
         let pref_b = StoredUserPreferences::load(amal_b_conn).unwrap();
 
         assert_eq!(pref_a.hmac_key, pref_b.hmac_key);
+
+        amal_a
+            .revoke_installations(vec![amal_b.installation_id().to_vec()])
+            .await
+            .unwrap();
+
+        let new_pref_a = StoredUserPreferences::load(amal_a_conn).unwrap();
+        assert_ne!(pref_a.hmac_key, new_pref_a.hmac_key);
     }
 }
diff --git a/xmtp_mls/src/identity_updates.rs b/xmtp_mls/src/identity_updates.rs
index 822c00bac..cb68afe1e 100644
--- a/xmtp_mls/src/identity_updates.rs
+++ b/xmtp_mls/src/identity_updates.rs
@@ -1,4 +1,6 @@
-use crate::storage::association_state::StoredAssociationState;
+use crate::storage::{
+    association_state::StoredAssociationState, user_preferences::StoredUserPreferences,
+};
 use futures::future::try_join_all;
 use std::collections::{HashMap, HashSet};
 use thiserror::Error;
@@ -350,6 +352,10 @@ where
             )
         }
 
+        // Cycle the HMAC key
+        let conn = self.store().conn()?;
+        StoredUserPreferences::new_hmac_key(&conn, &self.local_events)?;
+
         Ok(builder.build())
     }