diff --git a/backend/src/federation/authenticateCommunities.ts b/backend/src/federation/authenticateCommunities.ts
index 57e0fa57b..6b8796fbf 100644
--- a/backend/src/federation/authenticateCommunities.ts
+++ b/backend/src/federation/authenticateCommunities.ts
@@ -20,7 +20,7 @@ export async function startCommunityAuthentication(
   const foreignCom = await DbCommunity.findOneByOrFail({ publicKey: foreignFedCom.publicKey })
   if (foreignCom && foreignCom.communityUuid === null && foreignCom.authenticatedAt === null) {
     try {
-      const client = AuthenticationClientFactory.getInstance(homeFedCom)
+      const client = AuthenticationClientFactory.getInstance(foreignFedCom)
       // eslint-disable-next-line camelcase
       if (client instanceof V1_0_AuthenticationClient) {
         const args = new OpenConnectionArgs()
diff --git a/backend/src/federation/validateCommunities.ts b/backend/src/federation/validateCommunities.ts
index f497be2cb..686465ac7 100644
--- a/backend/src/federation/validateCommunities.ts
+++ b/backend/src/federation/validateCommunities.ts
@@ -59,7 +59,7 @@ export async function validateCommunities(): Promise<void> {
           const pubComInfo = await client.getPublicCommunityInfo()
           if (pubComInfo) {
             await writeForeignCommunity(dbCom, pubComInfo)
-            void startCommunityAuthentication(dbCom)
+            await startCommunityAuthentication(dbCom)
             logger.debug(`Federation: write publicInfo of community: name=${pubComInfo.name}`)
           } else {
             logger.warn('Federation: missing result of getPublicCommunityInfo')
diff --git a/federation/package.json b/federation/package.json
index 55fb408be..06e1f10fb 100644
--- a/federation/package.json
+++ b/federation/package.json
@@ -54,6 +54,7 @@
     "eslint-plugin-promise": "^6.1.1",
     "eslint-plugin-security": "^1.7.1",
     "eslint-plugin-type-graphql": "^1.0.0",
+    "graphql-tag": "2.12.6",
     "jest": "^27.2.4",
     "nodemon": "^2.0.7",
     "prettier": "^2.3.1",
diff --git a/federation/src/client/1_0/AuthenticationClient.ts b/federation/src/client/1_0/AuthenticationClient.ts
index 4437e2a69..eb23886bb 100644
--- a/federation/src/client/1_0/AuthenticationClient.ts
+++ b/federation/src/client/1_0/AuthenticationClient.ts
@@ -7,7 +7,6 @@ import { openConnectionCallback } from './query/openConnectionCallback'
 import { AuthenticationArgs } from '@/graphql/api/1_0/model/AuthenticationArgs'
 import { authenticate } from './query/authenticate'
 
-
 export class AuthenticationClient {
   dbCom: DbFederatedCommunity
   endpoint: string
@@ -27,12 +26,13 @@ export class AuthenticationClient {
     })
   }
 
-  async openConnectionCallback(args: OpenConnectionCallbackArgs): Promise<boolean | undefined> {
+  async openConnectionCallback(args: OpenConnectionCallbackArgs): Promise<boolean> {
     logger.debug('Authentication: openConnectionCallback with endpoint', this.endpoint, args)
     try {
       // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-      const { data } = await this.client.rawRequest(openConnectionCallback, { args })
-      if (!data?.openConnectionCallback) {
+      const { data } = await this.client.rawRequest<any>(openConnectionCallback, { args })
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+      if (data && data.openConnectionCallback) {
         logger.warn(
           'Authentication: openConnectionCallback without response data from endpoint',
           this.endpoint,
@@ -47,24 +47,24 @@ export class AuthenticationClient {
     } catch (err) {
       logger.error('Authentication: error on openConnectionCallback', err)
     }
+    return false
   }
 
-  async authenticate(args: AuthenticationArgs): Promise<string | undefined> {
+  async authenticate(args: AuthenticationArgs): Promise<string | null> {
     logger.debug('Authentication: authenticate with endpoint=', this.endpoint)
     try {
       // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
-      const { data } = await this.client.rawRequest(authenticate, {})
+      const { data } = await this.client.rawRequest<any>(authenticate, { args })
+      logger.debug('Authentication: after authenticate: data:', data)
       // eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
-      if (!data?.authenticate) {
-        logger.warn(
-          'Authentication: authenticate without response data from endpoint',
-          this.endpoint,
-        )
-        return
+      const authUuid: string = data?.authenticate.uuid
+      if (authUuid) {
+        logger.debug('Authentication: received authenticated uuid', authUuid)
+        return authUuid
       }
-      const 
     } catch (err) {
       logger.error('Authentication: authenticate  failed for endpoint', this.endpoint)
     }
+    return null
   }
 }
diff --git a/federation/src/client/1_0/query/authenticate.ts b/federation/src/client/1_0/query/authenticate.ts
index 3079268d9..59eb64646 100644
--- a/federation/src/client/1_0/query/authenticate.ts
+++ b/federation/src/client/1_0/query/authenticate.ts
@@ -2,6 +2,8 @@ import { gql } from 'graphql-request'
 
 export const authenticate = gql`
   mutation ($args: AuthenticateArgs!) {
-    authenticate(data: $args)
+    authenticate(data: $args) {
+      uuid
+    }
   }
 `
diff --git a/federation/src/graphql/api/1_0/model/AuthenticationArgs.ts b/federation/src/graphql/api/1_0/model/AuthenticationArgs.ts
index d0dc200da..5adc476a0 100644
--- a/federation/src/graphql/api/1_0/model/AuthenticationArgs.ts
+++ b/federation/src/graphql/api/1_0/model/AuthenticationArgs.ts
@@ -1,6 +1,6 @@
-import { ArgsType, Field } from 'type-graphql'
+import { Field, InputType } from 'type-graphql'
 
-@ArgsType()
+@InputType()
 export class AuthenticationArgs {
   @Field(() => String)
   oneTimeCode: string
diff --git a/federation/src/graphql/api/1_0/model/OpenConnectionArgs.ts b/federation/src/graphql/api/1_0/model/OpenConnectionArgs.ts
index 9752f4e6f..9afdbca5f 100644
--- a/federation/src/graphql/api/1_0/model/OpenConnectionArgs.ts
+++ b/federation/src/graphql/api/1_0/model/OpenConnectionArgs.ts
@@ -1,6 +1,6 @@
-import { ArgsType, Field } from 'type-graphql'
+import { Field, InputType } from 'type-graphql'
 
-@ArgsType()
+@InputType()
 export class OpenConnectionArgs {
   @Field(() => String)
   publicKey: string
diff --git a/federation/src/graphql/api/1_0/model/OpenConnectionCallbackArgs.ts b/federation/src/graphql/api/1_0/model/OpenConnectionCallbackArgs.ts
index fa4eb17b5..461f6c3d7 100644
--- a/federation/src/graphql/api/1_0/model/OpenConnectionCallbackArgs.ts
+++ b/federation/src/graphql/api/1_0/model/OpenConnectionCallbackArgs.ts
@@ -1,13 +1,10 @@
-import { ArgsType, Field } from 'type-graphql'
+import { Field, InputType } from 'type-graphql'
 
-@ArgsType()
+@InputType()
 export class OpenConnectionCallbackArgs {
   @Field(() => String)
   oneTimeCode: string
 
-  @Field(() => String)
-  publicKey: string
-
   @Field(() => String)
   url: string
 }
diff --git a/federation/src/graphql/api/1_0/resolver/AuthenticationResolver.ts b/federation/src/graphql/api/1_0/resolver/AuthenticationResolver.ts
index cd86e87da..d1595cd35 100644
--- a/federation/src/graphql/api/1_0/resolver/AuthenticationResolver.ts
+++ b/federation/src/graphql/api/1_0/resolver/AuthenticationResolver.ts
@@ -2,14 +2,13 @@
 import { Arg, Mutation, Resolver } from 'type-graphql'
 import { federationLogger as logger } from '@/server/logger'
 import { Community as DbCommunity } from '@entity/Community'
+import { FederatedCommunity as DbFedCommunity } from '@entity/FederatedCommunity'
 import { LogError } from '@/server/LogError'
 import { OpenConnectionArgs } from '../model/OpenConnectionArgs'
-import {
-  startOpenConnectionCallback,
-  startOpenConnectionRedirect,
-} from '../util/authenticateCommunity'
+import { startAuthentication, startOpenConnectionCallback } from '../util/authenticateCommunity'
 import { OpenConnectionCallbackArgs } from '../model/OpenConnectionCallbackArgs'
-import { ApiVersionType } from '@/client/enum/apiVersionType'
+import { CONFIG } from '@/config'
+import { AuthenticationArgs } from '../model/AuthenticationArgs'
 
 @Resolver()
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
@@ -28,7 +27,8 @@ export class AuthenticationResolver {
     if (!requestedCom) {
       throw new LogError(`unknown requesting community with publicKey`, args.publicKey)
     }
-    void startOpenConnectionRedirect(args, requestedCom, ApiVersionType.V1_0)
+    // no await to respond immediatly and invoke callback-request asynchron
+    void startOpenConnectionCallback(args, requestedCom, CONFIG.FEDERATION_API)
     return true
   }
 
@@ -38,14 +38,37 @@ export class AuthenticationResolver {
     args: OpenConnectionCallbackArgs,
   ): Promise<boolean> {
     logger.debug(`Authentication: openConnectionCallback() via apiVersion=1_0 ...`, args)
-    // first find with args.publicKey the community, which invokes openConnectionCallback
-    const callbackCom = await DbCommunity.findOneBy({
-      publicKey: Buffer.from(args.publicKey),
-    })
-    if (!callbackCom) {
-      throw new LogError(`unknown callback community with publicKey`, args.publicKey)
+    // TODO decrypt args.url with homeCom.privateKey and verify signing with callbackFedCom.publicKey
+    const endPoint = args.url.slice(0, args.url.lastIndexOf('/'))
+    const apiVersion = args.url.slice(args.url.lastIndexOf('/'), args.url.length)
+    const callbackFedCom = await DbFedCommunity.findOneBy({ endPoint, apiVersion })
+    if (!callbackFedCom) {
+      throw new LogError(`unknown callback community with url`, args.url)
     }
-    void startOpenConnectionCallback(args, callbackCom)
+    // no await to respond immediatly and invoke authenticate-request asynchron
+    void startAuthentication(args.oneTimeCode, callbackFedCom)
     return true
   }
+
+  @Mutation(() => String)
+  async authenticate(
+    @Arg('data')
+    args: AuthenticationArgs,
+  ): Promise<string | null> {
+    logger.debug(`Authentication: authenticate() via apiVersion=1_0 ...`, args)
+    const authCom = await DbCommunity.findOneByOrFail({ communityUuid: args.oneTimeCode })
+    logger.debug('Authentication: found authCom:', authCom)
+    if (authCom) {
+      // TODO decrypt args.uuid with authCom.publicKey
+      authCom.communityUuid = args.uuid
+      await DbCommunity.save(authCom)
+      logger.debug('Authentication: store authCom.uuid successfully:', authCom)
+      const homeCom = await DbCommunity.findOneByOrFail({ foreign: false })
+      // TODO encrypt homeCom.uuid with homeCom.privateKey
+      if (homeCom.communityUuid) {
+        return homeCom.communityUuid
+      }
+    }
+    return null
+  }
 }
diff --git a/federation/src/graphql/api/1_0/util/authenticateCommunity.ts b/federation/src/graphql/api/1_0/util/authenticateCommunity.ts
index b2a4a832c..65e9c3e6f 100644
--- a/federation/src/graphql/api/1_0/util/authenticateCommunity.ts
+++ b/federation/src/graphql/api/1_0/util/authenticateCommunity.ts
@@ -1,19 +1,19 @@
 import { OpenConnectionArgs } from '../model/OpenConnectionArgs'
 import { Community as DbCommunity } from '@entity/Community'
-import { FederatedCommunity as DbFederatedCommunity } from '@entity/FederatedCommunity'
+import { FederatedCommunity as DbFedCommunity } from '@entity/FederatedCommunity'
 import { federationLogger as logger } from '@/server/logger'
 import { OpenConnectionCallbackArgs } from '../model/OpenConnectionCallbackArgs'
 // eslint-disable-next-line camelcase
 import { randombytes_random } from 'sodium-native'
 import { AuthenticationClientFactory } from '@/client/AuthenticationClientFactory'
-import { ApiVersionType } from '@/client/enum/apiVersionType'
 // eslint-disable-next-line camelcase
 import { AuthenticationClient as V1_0_AuthenticationClient } from '@/client/1_0/AuthenticationClient'
+import { AuthenticationArgs } from '../model/AuthenticationArgs'
 
-export async function startOpenConnectionRedirect(
+export async function startOpenConnectionCallback(
   args: OpenConnectionArgs,
   requestedCom: DbCommunity,
-  api: ApiVersionType,
+  api: string,
 ): Promise<void> {
   logger.debug(
     `Authentication: startOpenConnectionRedirect()...`,
@@ -22,14 +22,13 @@ export async function startOpenConnectionRedirect(
     requestedCom,
   )
   try {
-    // TODO verify signing of args.url with requestedCom.publicKey and decrypt with homeCom.privateKey
     const homeCom = await DbCommunity.findOneByOrFail({ foreign: false })
-    const homeFedCom = await DbFederatedCommunity.findOneByOrFail({
+    const homeFedCom = await DbFedCommunity.findOneByOrFail({
       foreign: false,
       apiVersion: api,
     })
     const oneTimeCode = randombytes_random()
-    // store oneTimeCode in requestedCom.community_uuid for authenticate-request-identifier
+    // store oneTimeCode in requestedCom.community_uuid as authenticate-request-identifier
     requestedCom.communityUuid = oneTimeCode.toString()
     await DbCommunity.save(requestedCom)
 
@@ -38,8 +37,7 @@ export async function startOpenConnectionRedirect(
     if (client instanceof V1_0_AuthenticationClient) {
       const callbackArgs = new OpenConnectionCallbackArgs()
       callbackArgs.oneTimeCode = oneTimeCode.toString()
-      callbackArgs.publicKey = homeCom.publicKey.toString('hex')
-      // TODO signing of callbackArgs.url with requestedCom.publicKey and decrypt with homeCom.privateKey
+      // TODO encrypt callbackArgs.url with requestedCom.publicKey and sign it with homeCom.privateKey
       callbackArgs.url = homeFedCom.endPoint.endsWith('/')
         ? homeFedCom.endPoint
         : homeFedCom.endPoint + '/' + homeFedCom.apiVersion
@@ -54,21 +52,45 @@ export async function startOpenConnectionRedirect(
   }
 }
 
-export async function startOpenConnectionCallback(
-  args: OpenConnectionCallbackArgs,
-  callbackCom: DbCommunity,
+export async function startAuthentication(
+  oneTimeCode: string,
+  callbackFedCom: DbFedCommunity,
 ): Promise<void> {
-  logger.debug(
-    `Authentication: startOpenConnectionCallback()...`,
-    args.publicKey,
-    args.url,
-    callbackCom,
-  )
+  logger.debug(`Authentication: startAuthentication()...`, oneTimeCode, callbackFedCom)
   try {
-    // TODO verify signing of args.url with requestedCom.publicKey and decrypt with homeCom.privateKey
     const homeCom = await DbCommunity.findOneByOrFail({ foreign: false })
-    
-    
+    const homeFedCom = await DbFedCommunity.findOneByOrFail({
+      foreign: false,
+      apiVersion: callbackFedCom.apiVersion,
+    })
+
+    // TODO encrypt homeCom.uuid with homeCom.privateKey and sign it with callbackFedCom.publicKey
+    const client = AuthenticationClientFactory.getInstance(homeFedCom)
+    // eslint-disable-next-line camelcase
+    if (client instanceof V1_0_AuthenticationClient) {
+      const authenticationArgs = new AuthenticationArgs()
+      authenticationArgs.oneTimeCode = oneTimeCode
+      // TODO encrypt callbackArgs.url with requestedCom.publicKey and sign it with homeCom.privateKey
+      if (homeCom.communityUuid) {
+        authenticationArgs.uuid = homeCom.communityUuid
+      }
+      logger.debug(`Authentication: vor authenticate()...`, authenticationArgs)
+      const fedComUuid = await client.authenticate(authenticationArgs)
+      logger.debug(`Authentication: nach authenticate()...`, fedComUuid)
+      if (fedComUuid !== null) {
+        // TODO decrypt fedComUuid with callbackFedCom.publicKey
+        const callbackCom = await DbCommunity.findOneByOrFail({
+          foreign: true,
+          publicKey: callbackFedCom.publicKey,
+        })
+        callbackCom.communityUuid = fedComUuid
+        callbackCom.authenticatedAt = new Date()
+        await DbCommunity.save(callbackCom)
+        logger.debug('Authentication: Community Authentication successful:', callbackCom)
+      } else {
+        logger.error('Authentication: Community Authentication failed:', authenticationArgs)
+      }
+    }
   } catch (err) {
     logger.error('Authentication: error in startOpenConnectionCallback:', err)
   }
diff --git a/federation/src/graphql/schema.ts b/federation/src/graphql/schema.ts
index 0951c1000..d1be63b00 100644
--- a/federation/src/graphql/schema.ts
+++ b/federation/src/graphql/schema.ts
@@ -11,6 +11,14 @@ const schema = async (): Promise<GraphQLSchema> => {
     resolvers: [getApiResolvers()],
     // authChecker: isAuthorized,
     scalarsMap: [{ type: Decimal, scalar: DecimalScalar }],
+    validate: {
+      validationError: { target: false },
+      skipMissingProperties: true,
+      skipNullProperties: true,
+      skipUndefinedProperties: false,
+      forbidUnknownValues: true,
+      stopAtFirstError: true,
+    },
   })
 }
 
diff --git a/federation/test/extensions.ts b/federation/test/extensions.ts
deleted file mode 100644
index 262a9bcdb..000000000
--- a/federation/test/extensions.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-/* eslint-disable @typescript-eslint/no-unsafe-call */
-/* eslint-disable @typescript-eslint/no-unsafe-member-access */
-/* eslint-disable @typescript-eslint/restrict-template-expressions */
-/* eslint-disable @typescript-eslint/no-empty-interface */
-/* eslint-disable @typescript-eslint/no-unsafe-argument */
-
-import { Decimal } from 'decimal.js-light'
-
-expect.extend({
-  decimalEqual(received, value) {
-    const pass = new Decimal(value).equals(received.toString())
-    if (pass) {
-      return {
-        message: () => `expected ${received} to not equal ${value}`,
-        pass: true,
-      }
-    } else {
-      return {
-        message: () => `expected ${received} to equal ${value}`,
-        pass: false,
-      }
-    }
-  },
-})
-
-interface CustomMatchers<R = unknown> {
-  decimalEqual(value: number): R
-}
-
-declare global {
-  // eslint-disable-next-line @typescript-eslint/no-namespace
-  namespace jest {
-    interface Expect extends CustomMatchers {}
-    interface Matchers<R> extends CustomMatchers<R> {}
-    interface InverseAsymmetricMatchers extends CustomMatchers {}
-  }
-}
diff --git a/federation/test/helpers.test.ts b/federation/test/helpers.test.ts
deleted file mode 100644
index 69d8f3fa4..000000000
--- a/federation/test/helpers.test.ts
+++ /dev/null
@@ -1,7 +0,0 @@
-import { contributionDateFormatter } from '@test/helpers'
-
-describe('contributionDateFormatter', () => {
-  it('formats the date correctly', () => {
-    expect(contributionDateFormatter(new Date('Thu Feb 29 2024 13:12:11'))).toEqual('2/29/2024')
-  })
-})
diff --git a/federation/test/helpers.ts b/federation/test/helpers.ts
deleted file mode 100644
index 3b05edf4d..000000000
--- a/federation/test/helpers.ts
+++ /dev/null
@@ -1,62 +0,0 @@
-/* eslint-disable @typescript-eslint/unbound-method */
-/* eslint-disable @typescript-eslint/no-unsafe-assignment */
-/* eslint-disable @typescript-eslint/no-unsafe-member-access */
-/* eslint-disable @typescript-eslint/no-explicit-any */
-/* eslint-disable @typescript-eslint/no-unsafe-call */
-/* eslint-disable @typescript-eslint/no-unsafe-return */
-import { entities } from '@entity/index'
-import { createTestClient } from 'apollo-server-testing'
-
-import { createServer } from '@/server/createServer'
-
-import { logger } from './testSetup'
-
-export const headerPushMock = jest.fn((t) => {
-  context.token = t.value
-})
-
-const context = {
-  token: '',
-  setHeaders: {
-    push: headerPushMock,
-    forEach: jest.fn(),
-  },
-  clientTimezoneOffset: 0,
-}
-
-export const cleanDB = async () => {
-  // this only works as long we do not have foreign key constraints
-  for (const entity of entities) {
-    await resetEntity(entity)
-  }
-}
-
-export const testEnvironment = async (testLogger = logger) => {
-  const server = await createServer(testLogger) // context, testLogger, testI18n)
-  const con = server.con
-  const testClient = createTestClient(server.apollo)
-  const mutate = testClient.mutate
-  const query = testClient.query
-  return { mutate, query, con }
-}
-
-export const resetEntity = async (entity: any) => {
-  const items = await entity.find({ withDeleted: true })
-  if (items.length > 0) {
-    const ids = items.map((e: any) => e.id)
-    await entity.delete(ids)
-  }
-}
-
-export const resetToken = () => {
-  context.token = ''
-}
-
-// format date string as it comes from the frontend for the contribution date
-export const contributionDateFormatter = (date: Date): string => {
-  return `${date.getMonth() + 1}/${date.getDate()}/${date.getFullYear()}`
-}
-
-export const setClientTimezoneOffset = (offset: number): void => {
-  context.clientTimezoneOffset = offset
-}
diff --git a/federation/test/testSetup.ts b/federation/test/testSetup.ts
deleted file mode 100644
index 4341a1b49..000000000
--- a/federation/test/testSetup.ts
+++ /dev/null
@@ -1,22 +0,0 @@
-import { federationLogger as logger } from '@/server/logger'
-
-jest.setTimeout(1000000)
-
-jest.mock('@/server/logger', () => {
-  const originalModule = jest.requireActual('@/server/logger')
-  return {
-    __esModule: true,
-    ...originalModule,
-    backendLogger: {
-      addContext: jest.fn(),
-      trace: jest.fn(),
-      debug: jest.fn(),
-      warn: jest.fn(),
-      info: jest.fn(),
-      error: jest.fn(),
-      fatal: jest.fn(),
-    },
-  }
-})
-
-export { logger }
diff --git a/federation/yarn.lock b/federation/yarn.lock
index 1f3cdca2c..43acc0e8a 100644
--- a/federation/yarn.lock
+++ b/federation/yarn.lock
@@ -3058,7 +3058,7 @@ graphql-subscriptions@^1.0.0, graphql-subscriptions@^1.1.0:
   dependencies:
     iterall "^1.3.0"
 
-graphql-tag@^2.11.0:
+graphql-tag@2.12.6, graphql-tag@^2.11.0:
   version "2.12.6"
   resolved "https://registry.yarnpkg.com/graphql-tag/-/graphql-tag-2.12.6.tgz#d441a569c1d2537ef10ca3d1633b48725329b5f1"
   integrity sha512-FdSNcu2QQcWnM2VNvSCCDCVS5PpPqpzgFT8+GXzqJuoDd0CBncxCY278u4mhRO7tMgo2JjgJA5aZ+nWSQ/Z+xg==