Table of Contents
Advertisement
keyloader. When this mode is selected, keys are loaded
directly into a PID of 0-15 that corresponds to the PID
programmed for each channel (if applicable). A Keys
Table is not programmed with this mode.
SLN Mode - The SLN mode must be selected is either
OTAR (Over-The-Air-Rekeying) or the EFJohnson
System Management Assistant (PDA keyloader) is
used. It can also be used if OTAR is not used. With
this mode, keys are loaded into a SLN (Storage Loca-
tion Number), typically from 0-4095. A Keys Table
must then be programmed to link channel PIDs to a
specific SLN.
The use of this type of indirect linking allows keysets
and key IDs to be changed via OTAR while keeping
the mapping from the channel or talk group the same.
For example, as shown in Figure 10-1, PID 4 selects
SLN 24 which selects key slot 24 in both keysets. This
slot contains Key ID 69 in Keyset 1 and Key ID 91 in
Keyset 2. Only one keyset is active at a time.
10.2.4 MAINTAINING KEYS IN MEMORY
The radio may need to be connected to a constant
power source to preserve the encryption keys in
memory. The programming of the Infinite Key Reten-
tion parameter determines if keys are permanently
stored in memory or erased soon after power is
removed.
When Infinite Key Retention is enabled, keys are
stored in memory and are not lost when power is
removed. If it is disabled, they are maintained only
until the storage capacitance discharges. With 4100
models, storage capacitors maintain the supply voltage
(and encryption keys) for approximately 30 seconds
without power applied. Therefore, when changing the
battery, make sure to reattach another within 30
seconds.
With 5300 models, the keys are maintained for
approximately 8 hours with this feature disabled.
However, a tamper switch causes immediate key
erasure when the radio cover over the logic board is
removed.
10.2.5 ENCRYPTION KEY SELECT
NOTE: This feature is available on conventional
channels only.
SECURE COMMUNICATION (ENCRYPTION)
When multiple encryption keys are programmed
(see preceding information), the Key Select option
switch can be programmed to allow selection of
another key for the current channel. This feature
changes the PID (hardware location) of the key, and
the change is permanent (cycling power or selecting a
different channel does not reselect the original key).
Therefore, to switch back to the original key, it must
be manually reselected. Proceed as follows to select a
key:
1. Press the Key Select switch or select that menu
parameter and HWKEY x is displayed. The "x"
indicates the current key PID selection.
2. Press the Up/Down switch to display the desired key
and then press the F2 (Select) key to select it. Press
the F1 (Exit) or Key Select switch again to return the
display to normal operation.
10.2.6 ENCRYPTION KEY ERASE
A Key Erase menu item can be programmed that
allows the user to permanently erase all stored keys. If
OTAR TEK and KEK keys are stored, all keys of both
types are erased. This function can be used to ensure
that unauthorized encrypted calls can no longer be
placed or received by a radio.
10.2.7 ENCRYPTION ICON OPERATION
Basically, the encryption icon
ously whenever a secure call is received or trans-
mitted. Other operation is as follows:
•
When a secure call is received on a digital channel
in either the secure or clear mode, this icon flashes.
•
When a clear call is received on a digital channel in
the secure mode, this icon is on continuously.
•
There is a programmable option on the Radio Wide
screen to sound a beep whenever a secure call is
received on a clear channel.
10.3 CLEAR/SECURE STRAPPING
10.3.1 TRANSMIT MODE OPTIONS
The following transmit options are available
when encryption is selected:
63
is on continu-
Advertisement
Table of Contents
