diff --git a/keyserver/src/responders/user-responders.js b/keyserver/src/responders/user-responders.js
--- a/keyserver/src/responders/user-responders.js
+++ b/keyserver/src/responders/user-responders.js
@@ -468,6 +468,7 @@
   platformDetails: tPlatformDetails,
   watchedIDs: t.list(t.String),
   signedIdentityKeysBlob: t.maybe(signedIdentityKeysBlobValidator),
+  initialNotificationsEncryptedMessage: t.maybe(t.String),
 });
 
 async function siweAuthResponder(
@@ -482,6 +483,7 @@
     deviceTokenUpdateRequest,
     platformDetails,
     signedIdentityKeysBlob,
+    initialNotificationsEncryptedMessage,
   } = request;
   const calendarQuery = normalizeCalendarQuery(request.calendarQuery);
 
@@ -592,6 +594,7 @@
     calendarQuery,
     socialProof,
     signedIdentityKeysBlob,
+    initialNotificationsEncryptedMessage,
   });
 }
 
diff --git a/lib/types/siwe-types.js b/lib/types/siwe-types.js
--- a/lib/types/siwe-types.js
+++ b/lib/types/siwe-types.js
@@ -20,6 +20,7 @@
   +platformDetails: PlatformDetails,
   +watchedIDs: $ReadOnlyArray<string>,
   +signedIdentityKeysBlob?: ?SignedIdentityKeysBlob,
+  +initialNotificationsEncryptedMessage?: string,
 };
 
 export type SIWEAuthServerCall = {
diff --git a/native/account/siwe-panel.react.js b/native/account/siwe-panel.react.js
--- a/native/account/siwe-panel.react.js
+++ b/native/account/siwe-panel.react.js
@@ -25,6 +25,7 @@
 import { NavContext } from '../navigation/navigation-context.js';
 import { useSelector } from '../redux/redux-utils.js';
 import { nativeLogInExtraInfoSelector } from '../selectors/account-selectors.js';
+import { useInitialNotificationsEncryptedMessage } from '../utils/crypto-utils.js';
 import { defaultLandingURLPrefix } from '../utils/url-utils.js';
 
 const commSIWE = `${defaultLandingURLPrefix}/siwe`;
@@ -44,6 +45,8 @@
   const dispatchActionPromise = useDispatchActionPromise();
   const getSIWENonceCall = useServerCall(getSIWENonce);
   const siweAuthCall = useServerCall(siweAuth);
+  const callInitialNotificationsEncryptedMessage =
+    useInitialNotificationsEncryptedMessage();
 
   const logInExtraInfo = useSelector(state =>
     nativeLogInExtraInfoSelector({
@@ -140,15 +143,25 @@
   const handleSIWE = React.useCallback(
     async ({ message, signature }) => {
       const extraInfo = await logInExtraInfo();
+      const initialNotificationsEncryptedMessage =
+        await callInitialNotificationsEncryptedMessage();
 
       dispatchActionPromise(
         siweAuthActionTypes,
-        callSIWE(message, signature, extraInfo),
+        callSIWE(message, signature, {
+          ...extraInfo,
+          initialNotificationsEncryptedMessage,
+        }),
         undefined,
         ({ calendarQuery: extraInfo.calendarQuery }: LogInStartingPayload),
       );
     },
-    [logInExtraInfo, dispatchActionPromise, callSIWE],
+    [
+      logInExtraInfo,
+      dispatchActionPromise,
+      callSIWE,
+      callInitialNotificationsEncryptedMessage,
+    ],
   );
   const closeBottomSheet = bottomSheetRef.current?.close;
   const { nextMode } = props;