53SL ES Series Mobile Radio Operating Manual April 2009
8-3
Encryption Keys
Section 8 - Secure Communication (Encryption)
8.2.1
Key and Algorithm IDs
Each encryption key is programmed with a Key ID (also called Logical ID). This ID plus
the algorithm ID (ALGID) is transmitted in the message on digital channels. The radio
receiving the message must have a key with the same IDs in order to decrypt it.
8.2.2
PID / SLN Key Management Modes
The channels, talkgroups, and other calls that use encryption are linked to a specific
Physical ID (PID) when the radio is programmed. For example, Zone 1, channel 1 could
be programmed to select the key in PID 1 and Zone 1, channel 2 could select the key in
PID 3. The PID ranges are 0-63 when the PID mode is selected, and 1-64 when the SLN
mode is selected (see Figure 8.1).
Note
The term “SLN” from the Project 25 specification is equivalent to “CKR” (Common Key
Reference) also used to define this parameter.
Figure 8.1
Key Selection Example
More information on these modes follows.
PID Mode
- PID mode is analog encryption only. Since the EFJohnson Technologies
System Management Assistant (SMA) does not work with analog keys, PID mode can
be used only when keys are loaded using the Motorola KVL-3000 or KVL-3000 Plus
keyloader. When this mode is selected, keys are loaded directly into a PID of 0-63 that
corresponds to the PID programmed for each channel (if applicable). The Keys Table in
PC Configure is not programmed with this mode.
SLN Mode
- The SLN mode must be selected if either OTAR (Over-The-Air-
Rekeying) or the EFJohnson Technologies System Management Assistant (PDA
keyloader) is used. It can also be used if OTAR is not used. SLN mode is either analog
or digital encryption, and can also be used with the with the Motorola KVL-3000 Plus.
With this mode, keys are loaded into a SLN (Storage Location Number), typically from
0-4095. A Keys Table must then be programmed to link channel PIDs to a specific
SLN.
Algorithm ID
Keyset Name (Opt)
SLN 23
SLN 25
Algorithm ID
Keyset Name (Opt)
Key #21: Key ID 54
SLN 24
SLN 22
SLN 21
Keys Table
3
5
4
2
1
PID
Key #22: Key ID 65
Key #23: Key ID 67
Key #24: Key ID 69
Key #25: Key ID 73
Key #25: Key ID 90
Key #24: Key ID 91
Key #23: Key ID 99
Key #22: Key ID 98
Key #21: Key ID 94
Keyset 1
Keyset 2
Zone 1, Chan 2
Zone 2, Chan 4
Zone 2, Chan 5
Zone 3, Chan 1
Zone 3, Chan 2
