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34 | Services and Features
•
Class 2 — static key encryption (SCK).
•
Class 3 — derived key encryption (DCK, sometimes called the dynamic key), the Common Cipher Key (CCK),
and the Group Cipher Key (GCK).
TETRA DMO has two classes of encryption: Class 1 and Class 2.
The security features supported in the radio depend on the security mode.
Table 8: Security Features Required Per Security Class
Security Feature
Radio Initiated
Authentication
SwMI Initiated
Authentication
Mutual
Authentication
OTAR
SCK AIE
DCK AIE
GCK AIE
Note: In the current release the radio does not support the following security features:
•
Radio initiated authentication
•
Support for TEA4
•
Explicit authentication during DGNA
Enhanced Security, which consists of TMO Air Interface Encryption class 3G and DMO class 2, is a selling feature.
Clear Radios (Class 1)
A radio can be configured as a clear radio. In such case the radio identifies itself in registration as a Security Class 1
radio and does not support encryption. A Security Class 1 radio does not contain any encryption algorithms in its
software.
Static Cipher Key Encryption (Class 2)
The radio supports static AIE using a set of up to 32 static cipher keys (SCK) shared by the SwMI and all authorized
radios. The radio then determines which static keys to use based on the SCK Number (SCKN) and SCK version
number (SCK-VN) broadcast by the SwMI.
A radio can be configured to support static key encryption. In such case it identifies itself in registration as a Security
Class 2 radio, and attempts to negotiate Security Class 2 encryption. Each radio then uses either the TEA1 or the
TEA2 (TEA 3 — for Asia and Pacific) Key Stream Generator (KSG) algorithm. Each radio contains only one of
those algorithms in its software.
When Security Class 2 Encryption has been negotiated, encrypted PDUs are encrypted using SCK.
In DMO, the system manager may choose the SCK and the key may be distributed from the TMO SwMI using the
OTAR mechanism or provided manually using KVL.
Send Feedback
| |
Mode
Security Class 1
Security Class 2
Not Allowed
Not Allowed
Optional
Optional
Optional
Optional
N/A
Optional
N/A
Mandatory
N/A
N/A
N/A
N/A
Security Class 3
Security Class 3G
Not Allowed
Not Allowed
Mandatory
Mandatory
Optional
Optional
Mandatory
Mandatory
N/A
N/A
Mandatory
Mandatory
N/A
Mandatory
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