diff --git a/lib/types/holder-types.js b/lib/types/holder-types.js
new file mode 100644
--- /dev/null
+++ b/lib/types/holder-types.js
@@ -0,0 +1,19 @@
+// @flow
+
+export type HolderStatus =
+  | 'PENDING_ESTABLISHMENT'
+  | 'ESTABLISHED'
+  | 'NOT_ESTABLISHED'
+  | 'PENDING_REMOVAL'
+  | 'NOT_REMOVED';
+
+export type HolderInfo = {
+  +holder: string,
+  +status: HolderStatus,
+};
+
+export type HolderStore = {
+  +storedHolders: {
+    +[blobHash: string]: HolderInfo,
+  },
+};
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
@@ -70,6 +70,7 @@
   CalendarThreadFilter,
   SetCalendarDeletedFilterPayload,
 } from './filter-types.js';
+import type { HolderStore } from './holder-types.js';
 import type { IdentityAuthResult } from './identity-service-types';
 import type { IntegrityStore } from './integrity-types.js';
 import type {
@@ -200,6 +201,7 @@
   +tunnelbrokerDeviceToken: TunnelbrokerDeviceToken,
   +_persist: ?PersistState,
   +queuedDMOperations: QueuedDMOperations,
+  +holderStore: HolderStore,
   ...
 };
 
diff --git a/lib/utils/reducers-utils.test.js b/lib/utils/reducers-utils.test.js
--- a/lib/utils/reducers-utils.test.js
+++ b/lib/utils/reducers-utils.test.js
@@ -104,6 +104,9 @@
         entryQueue: {},
         membershipQueue: {},
       },
+      holderStore: {
+        storedHolders: {},
+      },
     };
     state = {
       ...defaultState,
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
@@ -104,6 +104,9 @@
     entryQueue: {},
     membershipQueue: {},
   },
+  holderStore: {
+    storedHolders: {},
+  },
 }: AppState);
 
 export { defaultState };
diff --git a/native/redux/persist.js b/native/redux/persist.js
--- a/native/redux/persist.js
+++ b/native/redux/persist.js
@@ -1475,6 +1475,15 @@
     },
     ops: [],
   }),
+  [83]: (state: AppState) => ({
+    state: {
+      ...state,
+      holderStore: {
+        storedHolders: {},
+      },
+    },
+    ops: [],
+  }),
 };
 
 // NOTE: renaming this object, and especially the `version` property
@@ -1485,7 +1494,7 @@
   storage: AsyncStorage,
   blacklist: persistBlacklist,
   debug: __DEV__,
-  version: 82,
+  version: 83,
   transforms: [
     messageStoreMessagesBlocklistTransform,
     reportStoreTransform,
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
@@ -12,6 +12,7 @@
 import type { EnabledApps } from 'lib/types/enabled-apps.js';
 import type { EntryStore } from 'lib/types/entry-types.js';
 import type { CalendarFilter } from 'lib/types/filter-types.js';
+import type { HolderStore } from 'lib/types/holder-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';
@@ -86,6 +87,7 @@
   +auxUserStore: AuxUserStore,
   +tunnelbrokerDeviceToken: TunnelbrokerDeviceToken,
   +queuedDMOperations: QueuedDMOperations,
+  +holderStore: HolderStore,
 };
 
 export { nonUserSpecificFieldsNative };
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
@@ -100,6 +100,9 @@
     entryQueue: {},
     membershipQueue: {},
   },
+  holderStore: {
+    storedHolders: {},
+  },
 });
 
 export { defaultWebState };
diff --git a/web/redux/handle-redux-migration-failure.js b/web/redux/handle-redux-migration-failure.js
--- a/web/redux/handle-redux-migration-failure.js
+++ b/web/redux/handle-redux-migration-failure.js
@@ -16,6 +16,7 @@
   'messageStore',
   'tunnelbrokerDeviceToken',
   'queuedDMOperations',
+  'holderStore',
 ];
 
 function handleReduxMigrationFailure(oldState: AppState): AppState {
diff --git a/web/redux/persist-constants.js b/web/redux/persist-constants.js
--- a/web/redux/persist-constants.js
+++ b/web/redux/persist-constants.js
@@ -3,6 +3,6 @@
 const rootKey = 'root';
 const rootKeyPrefix = 'persist:';
 const completeRootKey = `${rootKeyPrefix}${rootKey}`;
-const storeVersion = 82;
+const storeVersion = 83;
 
 export { rootKey, rootKeyPrefix, completeRootKey, storeVersion };
diff --git a/web/redux/persist.js b/web/redux/persist.js
--- a/web/redux/persist.js
+++ b/web/redux/persist.js
@@ -632,6 +632,15 @@
     },
     ops: [],
   }),
+  [83]: (state: AppState) => ({
+    state: {
+      ...state,
+      holderStore: {
+        storedHolders: {},
+      },
+    },
+    ops: [],
+  }),
 };
 
 const persistConfig: PersistConfig = {
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
@@ -44,6 +44,7 @@
 import type { EnabledApps } from 'lib/types/enabled-apps.js';
 import type { EntryStore } from 'lib/types/entry-types.js';
 import { type CalendarFilter } from 'lib/types/filter-types.js';
+import type { HolderStore } from 'lib/types/holder-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';
@@ -133,6 +134,7 @@
   +auxUserStore: AuxUserStore,
   +tunnelbrokerDeviceToken: TunnelbrokerDeviceToken,
   +queuedDMOperations: QueuedDMOperations,
+  +holderStore: HolderStore,
 };
 
 export type Action = $ReadOnly<