With symmetric key and autokey authentication, the highest level of NTP security is available.  HMC Level 2.12.0 and later provide windows that accept and generate key information to be  configured into the HMC NTP configuration. They can also issue NTP commands. The HMC offers the following symmetric key and autokey authentication and NTP commands: Symmetric key authentication is described in RFC 1305, which was made available in  NTP Version 3. Symmetric key encryption uses the same key for encryption and  decryption. Users that are exchanging data keep this key to themselves. Messages  encrypted with a secret key can be decrypted only with the same secret key. Symmetric  key authentication supports network address translation (NAT). This autokey uses public key cryptography, as described in RFC 5906, which was made  available in NTP Version 4. You can generate keys for the HMC NTP by clicking  Generate Local Host Key  in the Autokey Configuration window. This option issues the  ntp-keygen command to generate the specific key and certificate for this system. Autokey  authentication is not available with the NAT firewall. NTP command support is added to display the status of remote NTP servers and the  current NTP server (HMC). For more information about planning and setup for STP and NTP, see the following  publications: For HMC/SE Version 2.15.0, HDD encryption uses Trusted Platform Module (TPM) and Linux  Unified Key Setup (LUKS) technology. With the Audit and Log Management task, audit reports can be generated, viewed, saved,  and offloaded. The Customize Scheduled Operations task allows you to schedule audit report  generation, saving, and offloading. The Monitor System Events task allows Security Logs to  send email notifications by using the same type of filters and rules that are used for hardware  and operating system messages. HMC and SE security audit improvements HMC and SE HD encryption 10.5.10 Security and user ID management NTP symmetric key and autokey authentication GLYPH<SM590000> Symmetric key (NTP V3-V4) authentication GLYPH<SM590000> Symmetric key autokey (NTP V4) authentication GLYPH<SM590000> Issue NTP commands GLYPH<SM590000> Server Time Protocol Planning Guide , SG24-7280 GLYPH<SM590000> Server Time Protocol Implementation Guide , SG24-7281 GLYPH<SM590000> Server Time Protocol Recovery Guide,  SG24-7380 GLYPH<SM590000> Password is never stored in clear (one-way hash) GLYPH<SM590000> HMC/SE is a closed appliance; no means exist to get HDD GLYPH<SM590000> All  network traffic is TLS encrypted GLYPH<SM590000> HMC/SE features embedded firewall GLYPH<SM590000> Firmware is digitally signed and validated for delivery GLYPH<SM590000> Firmware Integrity Monitoring is used for any attempted tempering post delivery On z15 (continued emphasis on encryption): This section addresses security and user ID management considerations. 444  IBM z15 (8561) Technical Guide