diff --git a/lib/actions/integrity-actions.js b/lib/actions/integrity-actions.js
new file mode 100644
--- /dev/null
+++ b/lib/actions/integrity-actions.js
@@ -0,0 +1,5 @@
+// @flow
+
+const updateIntegrityStoreActionType = 'UPDATE_INTEGRITY_STORE';
+
+export { updateIntegrityStoreActionType };
diff --git a/lib/components/integrity-handler.react.js b/lib/components/integrity-handler.react.js
new file mode 100644
--- /dev/null
+++ b/lib/components/integrity-handler.react.js
@@ -0,0 +1,68 @@
+// @flow
+
+import * as React from 'react';
+import { useDispatch } from 'react-redux';
+
+import { updateIntegrityStoreActionType } from '../actions/integrity-actions.js';
+import type { RawThreadInfo } from '../types/thread-types.js';
+import { useSelector } from '../utils/redux-utils.js';
+
+const BATCH_SIZE = 50;
+function calculateThreadBatches(threadInfos: {
+  +[id: string]: RawThreadInfo,
+}): string[][] {
+  const threadIDs = Object.keys(threadInfos);
+  const batches = [];
+
+  let i = 0;
+  while (i < threadIDs.length) {
+    batches.push(threadIDs.slice(i, i + BATCH_SIZE));
+    i += BATCH_SIZE;
+  }
+
+  return batches;
+}
+
+function IntegrityHandler(): null {
+  const dispatch = useDispatch();
+
+  const threadInfos = useSelector(state => state.threadStore.threadInfos);
+  const integrityStore = useSelector(state => state.integrityStore);
+
+  const [batches, setBatches] = React.useState(null);
+  const timeout = React.useRef(null);
+
+  React.useEffect(() => {
+    if (!integrityStore.threadHashingComplete) {
+      clearTimeout(timeout.current);
+      setBatches(calculateThreadBatches(threadInfos));
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [integrityStore.threadHashingComplete]);
+
+  React.useEffect(() => {
+    if (!batches) {
+      return;
+    }
+    const [batch, ...rest] = batches;
+    if (!batch) {
+      dispatch({
+        type: updateIntegrityStoreActionType,
+        payload: { threadHashingComplete: true },
+      });
+      return;
+    }
+
+    dispatch({
+      type: updateIntegrityStoreActionType,
+      payload: { threadIDsToHash: batch },
+    });
+
+    timeout.current = setTimeout(() => setBatches(rest), 500);
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [batches]);
+
+  return null;
+}
+
+export default IntegrityHandler;
diff --git a/lib/reducers/integrity-reducer.js b/lib/reducers/integrity-reducer.js
new file mode 100644
--- /dev/null
+++ b/lib/reducers/integrity-reducer.js
@@ -0,0 +1,76 @@
+// @flow
+
+import { updateIntegrityStoreActionType } from '../actions/integrity-actions.js';
+import { siweAuthActionTypes } from '../actions/siwe-actions.js';
+import {
+  logInActionTypes,
+  registerActionTypes,
+} from '../actions/user-actions.js';
+import type { ThreadStoreOperation } from '../ops/thread-store-ops';
+import type { IntegrityStore } from '../types/integrity-types';
+import type { BaseAction } from '../types/redux-types.js';
+import { fullStateSyncActionType } from '../types/socket-types.js';
+import type { RawThreadInfo } from '../types/thread-types.js';
+import { hash } from '../utils/objects.js';
+
+function reduceIntegrityStore(
+  state: IntegrityStore,
+  action: BaseAction,
+  threadInfos: { +[string]: RawThreadInfo },
+  threadStoreOperations: $ReadOnlyArray<ThreadStoreOperation>,
+): IntegrityStore {
+  if (
+    action.type === logInActionTypes.success ||
+    action.type === siweAuthActionTypes.success ||
+    action.type === registerActionTypes.success ||
+    action.type === fullStateSyncActionType
+  ) {
+    return { threadHashes: {}, threadHashingComplete: false };
+  }
+  if (action.type === updateIntegrityStoreActionType) {
+    let newState = state;
+    if (action.payload.threadIDsToHash) {
+      const newThreadHashes = Object.fromEntries(
+        action.payload.threadIDsToHash
+          .map(id => [id, threadInfos[id]])
+          .filter(([, info]) => !!info)
+          .map(([id, info]) => [id, hash(info)]),
+      );
+
+      newState = {
+        ...newState,
+        threadHashes: {
+          ...newState.threadHashes,
+          ...newThreadHashes,
+        },
+      };
+    }
+    if (action.payload.threadHashingComplete) {
+      newState = {
+        ...newState,
+        threadHashingComplete: action.payload.threadHashingComplete,
+      };
+    }
+    return newState;
+  }
+  if (threadStoreOperations.length === 0) {
+    return state;
+  }
+  let processedThreadHashes = { ...state.threadHashes };
+  for (const operation of threadStoreOperations) {
+    if (operation.type === 'replace') {
+      processedThreadHashes[operation.payload.id] = hash(
+        operation.payload.threadInfo,
+      );
+    } else if (operation.type === 'remove') {
+      for (const id of operation.payload.ids) {
+        delete processedThreadHashes[id];
+      }
+    } else if (operation.type === 'remove_all') {
+      processedThreadHashes = {};
+    }
+  }
+  return { ...state, threadHashes: processedThreadHashes };
+}
+
+export { reduceIntegrityStore };
diff --git a/lib/reducers/master-reducer.js b/lib/reducers/master-reducer.js
--- a/lib/reducers/master-reducer.js
+++ b/lib/reducers/master-reducer.js
@@ -7,6 +7,7 @@
 import { reduceDraftStore } from './draft-reducer.js';
 import reduceEnabledApps from './enabled-apps-reducer.js';
 import { reduceEntryInfos } from './entry-reducer.js';
+import { reduceIntegrityStore } from './integrity-reducer.js';
 import reduceInviteLinks from './invite-links-reducer.js';
 import reduceKeyserverStore from './keyserver-reducer.js';
 import reduceLifecycleState from './lifecycle-state-reducer.js';
@@ -150,6 +151,12 @@
         state.threadActivityStore,
         action,
       ),
+      integrityStore: reduceIntegrityStore(
+        state.integrityStore,
+        action,
+        threadStore.threadInfos,
+        threadStoreOperations,
+      ),
     },
     storeOperations: {
       draftStoreOperations,
diff --git a/lib/types/integrity-types.js b/lib/types/integrity-types.js
new file mode 100644
--- /dev/null
+++ b/lib/types/integrity-types.js
@@ -0,0 +1,6 @@
+// @flow
+
+export type IntegrityStore = {
+  +threadHashes: { +[string]: number },
+  +threadHashingComplete: boolean,
+};
diff --git a/lib/types/redux-types.js b/lib/types/redux-types.js
--- a/lib/types/redux-types.js
+++ b/lib/types/redux-types.js
@@ -38,6 +38,7 @@
   CalendarThreadFilter,
   SetCalendarDeletedFilterPayload,
 } from './filter-types.js';
+import type { IntegrityStore } from './integrity-types.js';
 import type { KeyserverStore } from './keyserver-types.js';
 import type { LifecycleState } from './lifecycle-state-types.js';
 import type {
@@ -139,6 +140,7 @@
   +inviteLinksStore: InviteLinksStore,
   +keyserverStore: KeyserverStore,
   +threadActivityStore: ThreadActivityStore,
+  +integrityStore: IntegrityStore,
   ...
 };
 
@@ -1217,6 +1219,13 @@
   | {
       +type: 'UPDATE_THREAD_LAST_NAVIGATED',
       +payload: { +threadID: string, +time: number },
+    }
+  | {
+      +type: 'UPDATE_INTEGRITY_STORE',
+      payload: {
+        threadIDsToHash?: $ReadOnlyArray<string>,
+        threadHashingComplete?: boolean,
+      },
     };
 
 export type ActionPayload = ?(Object | Array<*> | $ReadOnlyArray<*> | string);
diff --git a/native/redux/default-state.js b/native/redux/default-state.js
--- a/native/redux/default-state.js
+++ b/native/redux/default-state.js
@@ -86,6 +86,7 @@
     isBackupEnabled: false,
   },
   threadActivityStore: {},
+  integrityStore: { threadHashes: {}, threadHashingComplete: false },
 }: AppState);
 
 export { defaultState };
diff --git a/native/redux/state-types.js b/native/redux/state-types.js
--- a/native/redux/state-types.js
+++ b/native/redux/state-types.js
@@ -7,6 +7,7 @@
 import type { EnabledApps } from 'lib/types/enabled-apps.js';
 import type { EntryStore, CalendarQuery } from 'lib/types/entry-types.js';
 import type { CalendarFilter } from 'lib/types/filter-types.js';
+import type { IntegrityStore } from 'lib/types/integrity-types.js';
 import type { KeyserverStore } from 'lib/types/keyserver-types.js';
 import type { LifecycleState } from 'lib/types/lifecycle-state-types.js';
 import type { InviteLinksStore } from 'lib/types/link-types.js';
@@ -60,4 +61,5 @@
   +keyserverStore: KeyserverStore,
   +threadActivityStore: ThreadActivityStore,
   +localSettings: LocalSettings,
+  +integrityStore: IntegrityStore,
 };
diff --git a/native/root.react.js b/native/root.react.js
--- a/native/root.react.js
+++ b/native/root.react.js
@@ -21,6 +21,7 @@
 
 import { EditUserAvatarProvider } from 'lib/components/edit-user-avatar-provider.react.js';
 import { ENSCacheProvider } from 'lib/components/ens-cache-provider.react.js';
+import IntegrityHandler from 'lib/components/integrity-handler.react.js';
 import { MediaCacheProvider } from 'lib/components/media-cache-provider.react.js';
 import { actionLogger } from 'lib/utils/action-logger.js';
 
@@ -242,6 +243,7 @@
       <ThemeHandler />
       <OrientationHandler />
       <BackupHandler />
+      <IntegrityHandler />
     </>
   );
   let navigation;
diff --git a/web/redux/default-state.js b/web/redux/default-state.js
--- a/web/redux/default-state.js
+++ b/web/redux/default-state.js
@@ -89,6 +89,7 @@
   },
   threadActivityStore: {},
   initialStateLoaded: false,
+  integrityStore: { threadHashes: {}, threadHashingComplete: false },
 });
 
 export { defaultWebState };
diff --git a/web/redux/redux-setup.js b/web/redux/redux-setup.js
--- a/web/redux/redux-setup.js
+++ b/web/redux/redux-setup.js
@@ -22,6 +22,7 @@
 import type { EnabledApps } from 'lib/types/enabled-apps.js';
 import type { EntryStore, CalendarQuery } from 'lib/types/entry-types.js';
 import { type CalendarFilter } from 'lib/types/filter-types.js';
+import type { IntegrityStore } from 'lib/types/integrity-types.js';
 import type { KeyserverStore } from 'lib/types/keyserver-types.js';
 import type { LifecycleState } from 'lib/types/lifecycle-state-types.js';
 import type { InviteLinksStore } from 'lib/types/link-types.js';
@@ -100,6 +101,7 @@
   +keyserverStore: KeyserverStore,
   +threadActivityStore: ThreadActivityStore,
   +initialStateLoaded: boolean,
+  +integrityStore: IntegrityStore,
 };
 
 export type Action =
diff --git a/web/root.js b/web/root.js
--- a/web/root.js
+++ b/web/root.js
@@ -9,6 +9,7 @@
 import { persistReducer, persistStore } from 'redux-persist';
 import thunk from 'redux-thunk';
 
+import IntegrityHandler from 'lib/components/integrity-handler.react.js';
 import { reduxLoggerMiddleware } from 'lib/utils/action-logger.js';
 
 import App from './app.react.js';
@@ -41,6 +42,7 @@
         </Router>
         <Socket />
         <SQLiteDataHandler />
+        <IntegrityHandler />
       </InitialReduxStateGate>
     </ErrorBoundary>
   </Provider>