Operating Manual

March 2008 5100 ES Models II/III Portable Radio Operating Manual 10-1
S ECTION
Section 10Secure Communication (Encryption)
This radio may be equipped to provide secure communication on some or all channels.
This feature encrypts the voice so that it can be understood only by someone using a radio
equipped with a similar encryption device and encryption codes.
When a secure call is received, the LED flashes Red and is indicated in the display. If
equipped with the Clear/Secure option switch and the current channel is programmed to
allow switch selection, secure communication can be manually enabled and disabled by
that switch. Otherwise, channels are strapped to Clear or Secure operation (see Section
10.3). Secure communication can be programmed on a per channel or per talk group basis
to operate in various ways. More information follows.
10.1 Encryption Algorithms
10.1.1 SecureNet™
SecureNet encryption digitizes the voice and then encrypts it using the DES algorithm. It
uses a 64-bit encryption key. The SecureNet protocols include the following algorithms:
• DES (Data Encryption Standard) provides a level of security, and also uses cipher
feedback. It was originally designed to be used only by the Federal government.
• DES-OFB - A form of DES encryption for digital channels that uses output feedback.
This protocol does not result in the degraded range that occurs with analog channels.