diff --git a/lib/selectors/socket-selectors.js b/lib/selectors/socket-selectors.js
index fcfed3889..8254bcb59 100644
--- a/lib/selectors/socket-selectors.js
+++ b/lib/selectors/socket-selectors.js
@@ -1,197 +1,240 @@
 // @flow
 
 import { createSelector } from 'reselect';
+import t from 'tcomb';
 
 import { currentCalendarQuery } from './nav-selectors.js';
 import {
   serverEntryInfo,
   serverEntryInfosObject,
   filterRawEntryInfosByCalendarQuery,
 } from '../shared/entry-utils.js';
 import threadWatcher from '../shared/thread-watcher.js';
 import type { SignedIdentityKeysBlob } from '../types/crypto-types.js';
-import type { RawEntryInfo, CalendarQuery } from '../types/entry-types.js';
+import {
+  type RawEntryInfo,
+  rawEntryInfoValidator,
+  type CalendarQuery,
+} from '../types/entry-types.js';
 import type { AppState } from '../types/redux-types.js';
 import type { ClientReportCreationRequest } from '../types/report-types.js';
 import {
   serverRequestTypes,
   type ClientServerRequest,
   type ClientClientResponse,
 } from '../types/request-types.js';
 import type { SessionState } from '../types/session-types.js';
 import type { OneTimeKeyGenerator } from '../types/socket-types.js';
-import type { RawThreadInfo } from '../types/thread-types.js';
-import type { CurrentUserInfo, UserInfos } from '../types/user-types.js';
+import {
+  type RawThreadInfo,
+  rawThreadInfoValidator,
+} from '../types/thread-types.js';
+import {
+  type CurrentUserInfo,
+  currentUserInfoValidator,
+  type UserInfos,
+  userInfosValidator,
+} from '../types/user-types.js';
 import { getConfig } from '../utils/config.js';
 import { minimumOneTimeKeysRequired } from '../utils/crypto-utils.js';
 import { values, hash } from '../utils/objects.js';
+import {
+  tID,
+  convertClientIDsToServerIDs,
+  keyserverPrefixID,
+  convertToNewIDSchema,
+} from '../utils/validation-utils.js';
 
 const queuedReports: (
   state: AppState,
 ) => $ReadOnlyArray<ClientReportCreationRequest> = createSelector(
   (state: AppState) => state.reportStore.queuedReports,
   (
     mainQueuedReports: $ReadOnlyArray<ClientReportCreationRequest>,
   ): $ReadOnlyArray<ClientReportCreationRequest> => mainQueuedReports,
 );
 
 const getClientResponsesSelector: (
   state: AppState,
 ) => (
   calendarActive: boolean,
   oneTimeKeyGenerator: ?OneTimeKeyGenerator,
   getSignedIdentityKeysBlob: ?() => Promise<SignedIdentityKeysBlob>,
   serverRequests: $ReadOnlyArray<ClientServerRequest>,
 ) => Promise<$ReadOnlyArray<ClientClientResponse>> = createSelector(
   (state: AppState) => state.threadStore.threadInfos,
   (state: AppState) => state.entryStore.entryInfos,
   (state: AppState) => state.userStore.userInfos,
   (state: AppState) => state.currentUserInfo,
   currentCalendarQuery,
   (
       threadInfos: { +[id: string]: RawThreadInfo },
       entryInfos: { +[id: string]: RawEntryInfo },
       userInfos: UserInfos,
       currentUserInfo: ?CurrentUserInfo,
       calendarQuery: (calendarActive: boolean) => CalendarQuery,
     ) =>
     async (
       calendarActive: boolean,
       oneTimeKeyGenerator: ?OneTimeKeyGenerator,
       getSignedIdentityKeysBlob: ?() => Promise<SignedIdentityKeysBlob>,
       serverRequests: $ReadOnlyArray<ClientServerRequest>,
     ): Promise<$ReadOnlyArray<ClientClientResponse>> => {
       const clientResponses = [];
       const serverRequestedPlatformDetails = serverRequests.some(
         request => request.type === serverRequestTypes.PLATFORM_DETAILS,
       );
       for (const serverRequest of serverRequests) {
         if (
           serverRequest.type === serverRequestTypes.PLATFORM &&
           !serverRequestedPlatformDetails
         ) {
           clientResponses.push({
             type: serverRequestTypes.PLATFORM,
             platform: getConfig().platformDetails.platform,
           });
         } else if (serverRequest.type === serverRequestTypes.PLATFORM_DETAILS) {
           clientResponses.push({
             type: serverRequestTypes.PLATFORM_DETAILS,
             platformDetails: getConfig().platformDetails,
           });
         } else if (serverRequest.type === serverRequestTypes.CHECK_STATE) {
-          const filteredEntryInfos = filterRawEntryInfosByCalendarQuery(
+          let filteredEntryInfos = filterRawEntryInfosByCalendarQuery(
             serverEntryInfosObject(values(entryInfos)),
             calendarQuery(calendarActive),
           );
+
+          if (convertToNewIDSchema) {
+            threadInfos = convertClientIDsToServerIDs(
+              keyserverPrefixID,
+              t.dict(tID, rawThreadInfoValidator),
+              threadInfos,
+            );
+            userInfos = convertClientIDsToServerIDs(
+              keyserverPrefixID,
+              userInfosValidator,
+              userInfos,
+            );
+            currentUserInfo = convertClientIDsToServerIDs(
+              keyserverPrefixID,
+              t.maybe(currentUserInfoValidator),
+              currentUserInfo,
+            );
+            filteredEntryInfos = convertClientIDsToServerIDs(
+              keyserverPrefixID,
+              t.dict(tID, rawEntryInfoValidator),
+              filteredEntryInfos,
+            );
+          }
+
           const hashResults = {};
           for (const key in serverRequest.hashesToCheck) {
             const expectedHashValue = serverRequest.hashesToCheck[key];
             let hashValue;
             if (key === 'threadInfos') {
               hashValue = hash(threadInfos);
             } else if (key === 'entryInfos') {
               hashValue = hash(filteredEntryInfos);
             } else if (key === 'userInfos') {
               hashValue = hash(userInfos);
             } else if (key === 'currentUserInfo') {
               hashValue = hash(currentUserInfo);
             } else if (key.startsWith('threadInfo|')) {
               const [, threadID] = key.split('|');
               hashValue = hash(threadInfos[threadID]);
             } else if (key.startsWith('entryInfo|')) {
               const [, entryID] = key.split('|');
               let rawEntryInfo = filteredEntryInfos[entryID];
               if (rawEntryInfo) {
                 rawEntryInfo = serverEntryInfo(rawEntryInfo);
               }
               hashValue = hash(rawEntryInfo);
             } else if (key.startsWith('userInfo|')) {
               const [, userID] = key.split('|');
               hashValue = hash(userInfos[userID]);
             } else {
               continue;
             }
             hashResults[key] = expectedHashValue === hashValue;
           }
 
           const { failUnmentioned } = serverRequest;
           if (failUnmentioned && failUnmentioned.threadInfos) {
             for (const threadID in threadInfos) {
               const key = `threadInfo|${threadID}`;
               const hashResult = hashResults[key];
               if (hashResult === null || hashResult === undefined) {
                 hashResults[key] = false;
               }
             }
           }
           if (failUnmentioned && failUnmentioned.entryInfos) {
             for (const entryID in filteredEntryInfos) {
               const key = `entryInfo|${entryID}`;
               const hashResult = hashResults[key];
               if (hashResult === null || hashResult === undefined) {
                 hashResults[key] = false;
               }
             }
           }
           if (failUnmentioned && failUnmentioned.userInfos) {
             for (const userID in userInfos) {
               const key = `userInfo|${userID}`;
               const hashResult = hashResults[key];
               if (hashResult === null || hashResult === undefined) {
                 hashResults[key] = false;
               }
             }
           }
 
           clientResponses.push({
             type: serverRequestTypes.CHECK_STATE,
             hashResults,
           });
         } else if (
           serverRequest.type === serverRequestTypes.MORE_ONE_TIME_KEYS &&
           oneTimeKeyGenerator
         ) {
           const keys: string[] = [];
           for (let i = 0; i < minimumOneTimeKeysRequired; ++i) {
             keys.push(oneTimeKeyGenerator(i));
           }
           clientResponses.push({
             type: serverRequestTypes.MORE_ONE_TIME_KEYS,
             keys,
           });
         } else if (
           serverRequest.type === serverRequestTypes.SIGNED_IDENTITY_KEYS_BLOB &&
           getSignedIdentityKeysBlob
         ) {
           const signedIdentityKeysBlob = await getSignedIdentityKeysBlob();
           clientResponses.push({
             type: serverRequestTypes.SIGNED_IDENTITY_KEYS_BLOB,
             signedIdentityKeysBlob,
           });
         }
       }
       return clientResponses;
     },
 );
 
 const sessionStateFuncSelector: (
   state: AppState,
 ) => (calendarActive: boolean) => SessionState = createSelector(
   (state: AppState) => state.messageStore.currentAsOf,
   (state: AppState) => state.updatesCurrentAsOf,
   currentCalendarQuery,
   (
       messagesCurrentAsOf: number,
       updatesCurrentAsOf: number,
       calendarQuery: (calendarActive: boolean) => CalendarQuery,
     ) =>
     (calendarActive: boolean): SessionState => ({
       calendarQuery: calendarQuery(calendarActive),
       messagesCurrentAsOf,
       updatesCurrentAsOf,
       watchedIDs: threadWatcher.getWatchedIDs(),
     }),
 );
 
 export { queuedReports, getClientResponsesSelector, sessionStateFuncSelector };