From: Harlan Stenn
Figure 1 shows a typical keys file used by the reference implementation when the OpenSSL library is installed. In this figure, for key IDs in he range 1-10, the key is interpreted as a printable ASCII string. For key IDs in the range 11-20, the key is a 40-character hex digit string. The key is truncated or zero-filled internally to either 128 or 160 bits, depending on the key type. The line can be edited later or new lines can be added to change any field. The key can be change to a password, such as 2late4Me for key ID 10. Note that two or more keys files can be combined in any order as long as the key IDs are distinct.
When ntpd is started, it reads the keys file specified by the keys command and installs the keys in the key cache. However, individual keys must be activated with the trustedkey configuration command before use. This allows, for instance, the installation of possibly several batches of keys and then activating a key remotely using ntpq or ntpdc. The requestkey command selects the key ID used as the password for the ntpdc utility, while the controlkey command selects the key ID used as the password for the ntpq utility.
-In addition to the above means, ntpd now supports Microsoft Windows MS-SNTP authentication using Active Directory services. This support was contributed by the Samba Team and is still in development. It is enabled using the mssntp flag of the restrict command described on the Access Control Options page. Note: Potential users should be aware that these services involve a TCP connection to another process that could potentially block, denying services to other users. Therefore, this flag should be used only for a dedicated server with no clients other than MS-SNTP.
+In addition to the above means, ntpd now supports Microsoft Windows MS-SNTP authentication using Active Directory services. This support was contributed by the Samba Team and is still in development. It is enabled using the mssntp flag of the restrict command described on the Access Control Options page. Note: Potential users should be aware that these services involve a TCP connection to another process that could potentially block, denying services to other users. Therefore, this flag should be used only for a dedicated server with no clients other than MS-SNTP.
See the Autokey Public-Key Authentication page.