User guide

Security planning Chapter 2: Planning considerations
2-22
phn-2513_004v000 (Oct 2012)
Security planning
When planning PTP 800 links to operate in secure mode, follow the process described in
this section.
Planning for SNTP operation
To prepare for Simple Network Time Protocol (SNTP) operation:
• Identify the time zone and daylight saving requirements that apply to the system.
• Determine whether or not there is a requirement to synchronize the PTP 800 clock with
an SNTP server at regular intervals. If SNTP server synchronization is not required,
the clock can be set to run manually. The clock is battery backed and will continue to
operate for several days after the CMU is switched off.
• If SNTP server synchronization is required, identify the details of one or two SNTP
servers: IP address and server key.
• For secure applications, the PTP 800 can be configured to authenticate received NTP
messages using the DES or MD5 protocols.
Planning for AES encryption
To prepare for wireless link encryption:
• Choose 128-bit or 256-bit AES encryption.
• Use a cryptographic key generator to generate an encryption key for AES. The key
length is dictated by the selected AES encryption algorithm (128 or 256 bits). The same
encryption key is required at each link end.