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
@@ -49,6 +49,7 @@
 import {
   identityKeysBlobValidator,
   signedIdentityKeysBlobValidator,
+  olmSessionInitializationKeysValidator,
 } from 'lib/utils/crypto-utils.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { values } from 'lib/utils/objects.js';
@@ -214,6 +215,9 @@
   // old clients, but we no longer do anything with it.
   primaryIdentityPublicKey: t.maybe(tRegex(primaryIdentityPublicKeyRegex)),
   signedIdentityKeysBlob: t.maybe(signedIdentityKeysBlobValidator),
+  notificationsSessionInitializationKeys: t.maybe(
+    olmSessionInitializationKeysValidator,
+  ),
 });
 
 async function accountCreationResponder(
@@ -361,6 +365,9 @@
   // old clients, but we no longer do anything with it.
   primaryIdentityPublicKey: t.maybe(tRegex(primaryIdentityPublicKeyRegex)),
   signedIdentityKeysBlob: t.maybe(signedIdentityKeysBlobValidator),
+  notificationsSessionInitializationKeys: t.maybe(
+    olmSessionInitializationKeysValidator,
+  ),
 });
 
 async function logInResponder(
@@ -446,6 +453,9 @@
   platformDetails: tPlatformDetails,
   watchedIDs: t.list(t.String),
   signedIdentityKeysBlob: t.maybe(signedIdentityKeysBlobValidator),
+  notificationsSessionInitializationKeys: t.maybe(
+    olmSessionInitializationKeysValidator,
+  ),
 });
 
 async function siweAuthResponder(
diff --git a/lib/types/account-types.js b/lib/types/account-types.js
--- a/lib/types/account-types.js
+++ b/lib/types/account-types.js
@@ -1,6 +1,9 @@
 // @flow
 
-import type { SignedIdentityKeysBlob } from './crypto-types.js';
+import type {
+  SignedIdentityKeysBlob,
+  OLMSessionInitializationKeys,
+} from './crypto-types.js';
 import type { PlatformDetails } from './device-types.js';
 import type {
   CalendarQuery,
@@ -104,6 +107,7 @@
   +calendarQuery: CalendarQuery,
   +deviceTokenUpdateRequest?: ?DeviceTokenUpdateRequest,
   +signedIdentityKeysBlob?: SignedIdentityKeysBlob,
+  +notificationsSessionInitializationKeys?: OLMSessionInitializationKeys,
 };
 
 export type LogInInfo = {
diff --git a/lib/types/crypto-types.js b/lib/types/crypto-types.js
--- a/lib/types/crypto-types.js
+++ b/lib/types/crypto-types.js
@@ -16,6 +16,11 @@
   +curve25519: { +[string]: string },
 };
 
+export type OLMSessionInitializationKeys = {
+  +prekey: OLMPrekey,
+  +oneTimeKeysBatch: OLMOneTimeKeys,
+};
+
 export type PickledOLMAccount = {
   +picklingKey: string,
   +pickledAccount: string,
diff --git a/lib/utils/crypto-utils.js b/lib/utils/crypto-utils.js
--- a/lib/utils/crypto-utils.js
+++ b/lib/utils/crypto-utils.js
@@ -18,6 +18,22 @@
   curve25519: tRegex(primaryIdentityPublicKeyRegex),
 });
 
+const olmPrekeyValidator: TInterface = tShape({
+  curve25519: tShape({
+    id: t.String,
+    key: t.String,
+  }),
+});
+
+const olmOneTimeKeysValidator: TInterface = tShape({
+  curve25519: t.dict(t.String, t.String),
+});
+
+const olmSessionInitializationKeysValidator: TInterface = tShape({
+  prekey: olmPrekeyValidator,
+  oneTimeKeysBatch: olmOneTimeKeysValidator,
+});
+
 const identityKeysBlobValidator: TInterface = tShape({
   primaryIdentityPublicKeys: olmIdentityKeysValidator,
   notificationIdentityPublicKeys: olmIdentityKeysValidator,
@@ -27,4 +43,7 @@
   minimumOneTimeKeysRequired,
   signedIdentityKeysBlobValidator,
   identityKeysBlobValidator,
+  olmPrekeyValidator,
+  olmOneTimeKeysValidator,
+  olmSessionInitializationKeysValidator,
 };
diff --git a/native/selectors/account-selectors.js b/native/selectors/account-selectors.js
--- a/native/selectors/account-selectors.js
+++ b/native/selectors/account-selectors.js
@@ -31,9 +31,20 @@
         payload: blobPayload,
         signature,
       };
+      const [notificationsPrekey, notificationsOneTimeKeys] = await Promise.all(
+        [
+          commCoreModule.generateNotificationsPrekey(),
+          commCoreModule.getNotificationsOneTimeKeys(1),
+        ],
+      );
+      const notificationsSessionInitializationKeys = {
+        prekey: notificationsPrekey,
+        oneTimeKeysBatch: notificationsOneTimeKeys,
+      };
       return {
         ...logInExtraInfoFunc(calendarActive),
         signedIdentityKeysBlob,
+        notificationsSessionInitializationKeys,
       };
     };
     return loginExtraFuncWithIdentityKey;