diff --git a/admin/src/components/AiChat.vue b/admin/src/components/AiChat.vue
index ca1d3a93a..d95d23ecc 100644
--- a/admin/src/components/AiChat.vue
+++ b/admin/src/components/AiChat.vue
@@ -31,15 +31,21 @@
 </template>
 
 <script setup>
-import { ref, computed } from 'vue'
+import { ref, computed, onMounted } from 'vue'
 import { useI18n } from 'vue-i18n'
-import { useMutation } from '@vue/apollo-composable'
-import { sendMessage as sendMessageMutation } from '../graphql/aiChat.graphql'
+import { useMutation, useQuery } from '@vue/apollo-composable'
+import {
+  sendMessage as sendMessageMutation,
+  resumeChat,
+  deleteThread,
+} from '../graphql/aiChat.graphql'
 import { useAppToast } from '@/composables/useToast'
 
 const { t } = useI18n()
-const { toastError } = useAppToast()
+const { toastError, toastSuccess } = useAppToast()
 const response = useMutation(sendMessageMutation, { input: ref('') })
+const deleteResponse = useMutation(deleteThread, { threadId: ref('') })
+const { result: resumeChatResult, refetch: resumeChatRefetch } = useQuery(resumeChat)
 
 const isChatOpen = ref(false)
 const newMessage = ref('')
@@ -51,6 +57,21 @@ const toggleButtonVariant = computed(() => (isChatOpen.value ? 'secondary' : 'pr
 
 const toggleChat = () => {
   isChatOpen.value = !isChatOpen.value
+  if (!isChatOpen.value && threadId.value && threadId.value.length > 0) {
+    // delete thread on closing chat
+    deleteResponse
+      .mutate({ threadId: threadId.value })
+      .then((result) => {
+        threadId.value = ''
+        messages.value = []
+        if (result.data.deleteThread) {
+          toastSuccess(t('ai.chat-thread-deleted'))
+        }
+      })
+      .catch((error) => {
+        toastError(t('ai.error-chat-thread-deleted', { error }))
+      })
+  }
 }
 
 const sendMessage = () => {
@@ -73,6 +94,19 @@ const sendMessage = () => {
     newMessage.value = ''
   }
 }
+
+onMounted(async () => {
+  if (messages.value.length === 0) {
+    loading.value = true
+    await resumeChatRefetch()
+    const messagesFromServer = resumeChatResult.value.resumeChat
+    if (messagesFromServer && messagesFromServer.length > 0) {
+      threadId.value = messagesFromServer[0].threadId
+      messages.value = messagesFromServer
+    }
+    loading.value = false
+  }
+})
 </script>
 
 <style scoped>
diff --git a/admin/src/graphql/aiChat.graphql b/admin/src/graphql/aiChat.graphql
index 7d4d726eb..30f7c7f82 100644
--- a/admin/src/graphql/aiChat.graphql
+++ b/admin/src/graphql/aiChat.graphql
@@ -1,7 +1,17 @@
+#import './fragments.graphql'
+
 mutation sendMessage($input: OpenaiMessage!) {
   sendMessage(input: $input) {
-    content
-    role
-    threadId
+    ...AiChatMessageFields
+  }
+}
+
+mutation deleteThread($threadId: String!) {
+  deleteThread(threadId: $threadId)
+}
+
+query resumeChat {
+  resumeChat {
+    ...AiChatMessageFields
   }
 }
\ No newline at end of file
diff --git a/admin/src/graphql/fragments.graphql b/admin/src/graphql/fragments.graphql
index 77bf61a7c..537a8e813 100644
--- a/admin/src/graphql/fragments.graphql
+++ b/admin/src/graphql/fragments.graphql
@@ -21,3 +21,9 @@ fragment ProjectBrandingCommonFields on ProjectBranding {
   newUserToSpace
   logoUrl
 }
+
+fragment AiChatMessageFields on ChatGptMessage {
+  content
+  role
+  threadId
+}
\ No newline at end of file
diff --git a/admin/src/locales/de.json b/admin/src/locales/de.json
index 6c853c93c..14c55f991 100644
--- a/admin/src/locales/de.json
+++ b/admin/src/locales/de.json
@@ -4,7 +4,9 @@
   "ai": {
     "chat": "Chat",
     "chat-open": "Chat öffnen",
-    "chat-placeholder": "Schreibe eine Nachricht..."
+    "chat-placeholder": "Schreibe eine Nachricht...",
+    "chat-thread-deleted": "Chatverlauf gelöscht",
+    "error-chat-thread-deleted": "Fehler beim Löschen des Chatverlaufs: {error}"
   },
   "alias": "Alias",
   "all_emails": "Alle Nutzer",
diff --git a/admin/src/locales/en.json b/admin/src/locales/en.json
index 046b2f9f6..f89329580 100644
--- a/admin/src/locales/en.json
+++ b/admin/src/locales/en.json
@@ -4,7 +4,9 @@
   "ai": {
     "chat": "Chat",
     "chat-open": "Open chat",
-    "chat-placeholder": "Type your message here..."
+    "chat-placeholder": "Type your message here...",
+    "chat-thread-deleted": "Chat thread has been deleted",
+    "error-chat-thread-deleted": "Error while deleting chat thread: {error}"
   },
   "alias": "Alias",
   "all_emails": "All users",
diff --git a/backend/.env.test_e2e b/backend/.env.test_e2e
index 8b6559e97..d92135376 100644
--- a/backend/.env.test_e2e
+++ b/backend/.env.test_e2e
@@ -2,6 +2,7 @@
 JWT_EXPIRES_IN=2m
 
 GDT_ACTIVE=false
+OPENAI_ACTIVE=false
 
 # Email
 EMAIL=true
diff --git a/backend/Dockerfile b/backend/Dockerfile
index 2375568e6..a1325fb64 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -1,7 +1,7 @@
 ##################################################################################
 # BASE ###########################################################################
 ##################################################################################
-FROM node:18.20.7-alpine3.21 as base
+FROM node:18.20.7-bookworm-slim as base
 
 # ENVs (available in production aswell, can be overwritten by commandline or env file)
 ## DOCKER_WORKDIR would be a classical ARG, but that is not multi layer persistent - shame
diff --git a/backend/package.json b/backend/package.json
index b68663ecc..c00fa9028 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -50,7 +50,7 @@
     "pug": "^3.0.2",
     "random-bigint": "^0.0.1",
     "reflect-metadata": "^0.1.13",
-    "sodium-native": "^3.3.0",
+    "sodium-native": "^3.4.1",
     "type-graphql": "^1.1.1",
     "typed-rest-client": "^1.8.11",
     "uuid": "^8.3.2",
diff --git a/backend/src/apis/openai/OpenaiClient.ts b/backend/src/apis/openai/OpenaiClient.ts
index 36d300bd5..3a58f103e 100644
--- a/backend/src/apis/openai/OpenaiClient.ts
+++ b/backend/src/apis/openai/OpenaiClient.ts
@@ -71,6 +71,49 @@ export class OpenaiClient {
     return messageThread.id
   }
 
+  /**
+   * Resumes the last message thread for the given user.
+   * @param user
+   * @returns
+   */
+  public async resumeThread(user: User): Promise<MessageModel[]> {
+    const openaiThreadEntity = await OpenaiThreads.findOne({
+      where: { userId: user.id },
+      order: { createdAt: 'DESC' },
+    })
+    if (!openaiThreadEntity) {
+      // logger.warn(`No openai thread found for user: ${user.id}`)
+      return []
+    }
+    const threadMessages = (
+      await this.openai.beta.threads.messages.list(openaiThreadEntity.id, { order: 'desc' })
+    ).getPaginatedItems()
+
+    logger.info(`Resumed thread: ${openaiThreadEntity.id}`)
+    return threadMessages
+      .map(
+        (message) =>
+          new MessageModel(
+            this.messageContentToString(message),
+            message.role,
+            openaiThreadEntity.id,
+          ),
+      )
+      .reverse()
+  }
+
+  public async deleteThread(threadId: string): Promise<boolean> {
+    const result = await this.openai.beta.threads.del(threadId)
+    if (result.deleted) {
+      await OpenaiThreads.delete({ id: threadId })
+      logger.info(`Deleted thread: ${threadId}`)
+      return true
+    } else {
+      logger.warn(`Failed to delete thread: ${threadId}`)
+      return false
+    }
+  }
+
   public async addMessage(message: MessageModel, threadId: string): Promise<void> {
     const threadMessages = await this.openai.beta.threads.messages.create(threadId, message)
     logger.info(`Added message to thread: ${threadMessages.id}`)
@@ -94,7 +137,7 @@ export class OpenaiClient {
     return new MessageModel(this.messageContentToString(message), 'assistant')
   }
 
-  messageContentToString(message: Message): string {
+  private messageContentToString(message: Message): string {
     if (message.content.length > 1) {
       logger.warn(`More than one content in message: ${message.id}`, message.content)
     }
diff --git a/backend/src/apis/openai/model/Message.ts b/backend/src/apis/openai/model/Message.ts
index d626c5341..e9a5e86a4 100644
--- a/backend/src/apis/openai/model/Message.ts
+++ b/backend/src/apis/openai/model/Message.ts
@@ -1,10 +1,11 @@
 export class Message {
   content: string
   role: 'user' | 'assistant' = 'user'
-  threadId: string
+  threadId?: string
 
-  constructor(content: string, role: 'user' | 'assistant' = 'user') {
+  constructor(content: string, role: 'user' | 'assistant' = 'user', threadId?: string) {
     this.content = content
     this.role = role
+    this.threadId = threadId
   }
 }
diff --git a/backend/src/graphql/resolver/AiChatResolver.ts b/backend/src/graphql/resolver/AiChatResolver.ts
index 15b5e919b..7c1acba73 100644
--- a/backend/src/graphql/resolver/AiChatResolver.ts
+++ b/backend/src/graphql/resolver/AiChatResolver.ts
@@ -1,4 +1,4 @@
-import { Resolver, Mutation, Authorized, Ctx, Arg } from 'type-graphql'
+import { Resolver, Mutation, Authorized, Ctx, Arg, Query } from 'type-graphql'
 
 import { OpenaiMessage } from '@input/OpenaiMessage'
 import { ChatGptMessage } from '@model/ChatGptMessage'
@@ -10,6 +10,30 @@ import { Context } from '@/server/context'
 
 @Resolver()
 export class AiChatResolver {
+  @Authorized([RIGHTS.AI_SEND_MESSAGE])
+  @Query(() => [ChatGptMessage])
+  async resumeChat(@Ctx() context: Context): Promise<ChatGptMessage[]> {
+    const openaiClient = OpenaiClient.getInstance()
+    if (!openaiClient) {
+      return Promise.resolve([new ChatGptMessage({ content: 'OpenAI API is not enabled' })])
+    }
+    if (!context.user) {
+      return Promise.resolve([new ChatGptMessage({ content: 'User not found' })])
+    }
+    const messages = await openaiClient.resumeThread(context.user)
+    return messages.map((message) => new ChatGptMessage(message))
+  }
+
+  @Authorized([RIGHTS.AI_SEND_MESSAGE])
+  @Mutation(() => Boolean)
+  async deleteThread(@Arg('threadId') threadId: string): Promise<boolean> {
+    const openaiClient = OpenaiClient.getInstance()
+    if (!openaiClient) {
+      return false
+    }
+    return openaiClient.deleteThread(threadId)
+  }
+
   @Authorized([RIGHTS.AI_SEND_MESSAGE])
   @Mutation(() => ChatGptMessage)
   async sendMessage(
diff --git a/backend/src/graphql/resolver/UserResolver.ts b/backend/src/graphql/resolver/UserResolver.ts
index ad7e983dc..b6edab784 100644
--- a/backend/src/graphql/resolver/UserResolver.ts
+++ b/backend/src/graphql/resolver/UserResolver.ts
@@ -520,7 +520,6 @@ export class UserResolver {
         'Please enter a valid password with at least 8 characters, upper and lower case letters, at least one number and one special character!',
       )
     }
-
     // load code
     const userContact = await DbUserContact.findOneOrFail({
       where: { emailVerificationCode: code },
diff --git a/backend/src/password/EncryptionWorker.ts b/backend/src/password/EncryptionWorker.ts
index 36c08f1b6..ec39e8c3b 100644
--- a/backend/src/password/EncryptionWorker.ts
+++ b/backend/src/password/EncryptionWorker.ts
@@ -14,6 +14,7 @@ import {
   crypto_pwhash,
   crypto_shorthash,
 } from 'sodium-native'
+import { createHash } from 'node:crypto'
 
 export const SecretKeyCryptographyCreateKey = (
   salt: string,
@@ -21,12 +22,29 @@ export const SecretKeyCryptographyCreateKey = (
   configLoginAppSecret: Buffer,
   configLoginServerKey: Buffer,
 ): bigint => {
+  /*
+  console.log('SecretKeyCryptographyCreateKey')
   const state = Buffer.alloc(crypto_hash_sha512_STATEBYTES)
   crypto_hash_sha512_init(state)
+  console.log('before salt')
+  console.log('salt as buffer', Buffer.from(salt).toString('hex'))
   crypto_hash_sha512_update(state, Buffer.from(salt))
+  console.log('before configLoginAppSecret')
+  console.log('configLoginAppSecret', configLoginAppSecret.toString('hex'))
   crypto_hash_sha512_update(state, configLoginAppSecret)
   const hash = Buffer.alloc(crypto_hash_sha512_BYTES)
+  console.log('hash buffer size', hash.length)
+  console.log('before final')
+  console.log(typeof crypto_hash_sha512_final)
   crypto_hash_sha512_final(state, hash)
+  console.log('after final')
+  console.log('hash', hash.toString('hex'))
+*/
+  const state = createHash('sha512')
+  state.update(Buffer.from(salt))
+  state.update(configLoginAppSecret)
+  const hash = state.digest()
+  console.log('hash', hash.toString('hex'))
 
   const encryptionKey = Buffer.alloc(crypto_box_SEEDBYTES)
   const opsLimit = 10
diff --git a/backend/src/password/EncryptorUtils.ts b/backend/src/password/EncryptorUtils.ts
index f4dc00b6c..243917944 100644
--- a/backend/src/password/EncryptorUtils.ts
+++ b/backend/src/password/EncryptorUtils.ts
@@ -58,6 +58,7 @@ export const SecretKeyCryptographyCreateKey = async (
     }
     let result: Promise<bigint>
     if (encryptionWorkerPool) {
+      console.log('encrypt password with worker')
       result = (await encryptionWorkerPool.exec('SecretKeyCryptographyCreateKey', [
         salt,
         password,
@@ -65,6 +66,7 @@ export const SecretKeyCryptographyCreateKey = async (
         configLoginServerKey,
       ])) as Promise<bigint>
     } else {
+      console.log('encrypt password without worker')
       result = Promise.resolve(
         SecretKeyCryptographyCreateKeySync(
           salt,
diff --git a/backend/yarn.lock b/backend/yarn.lock
index c67e14dd0..b1a3ee3cf 100644
--- a/backend/yarn.lock
+++ b/backend/yarn.lock
@@ -6594,7 +6594,7 @@ slick@^1.12.2:
   resolved "https://registry.yarnpkg.com/slick/-/slick-1.12.2.tgz#bd048ddb74de7d1ca6915faa4a57570b3550c2d7"
   integrity sha512-4qdtOGcBjral6YIBCWJ0ljFSKNLz9KkhbWtuGvUyRowl1kxfuE1x/Z/aJcaiilpb3do9bl5K7/1h9XC5wWpY/A==
 
-sodium-native@^3.3.0:
+sodium-native@^3.4.1:
   version "3.4.1"
   resolved "https://registry.yarnpkg.com/sodium-native/-/sodium-native-3.4.1.tgz#44616c07ccecea15195f553af88b3e574b659741"
   integrity sha512-PaNN/roiFWzVVTL6OqjzYct38NSXewdl2wz8SRB51Br/MLIJPrbM3XexhVWkq7D3UWMysfrhKVf1v1phZq6MeQ==