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ESK

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M/A-COM Introduces EDACS Security Key (ESK) for Enhanced Radio System Security

Feature Provides Additional Protection to Restrict Programming, Eavesdropping and Unauthorized Transmission

Lowell, MA, April 24, 2002

M/A-COM, Inc. a unit of Tyco Electronics and a leading manufacturer of critical radio systems deployed around the world, today announced availability of the Enhanced Digital Access Communications System (EDACS) Security Key (ESK) to provide heightened security on EDACS and ProVoice radio systems. This new feature provides additional protection against eavesdropping and unauthorized transmissions on critical communications systems.

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Using EDACS ESK, each customer is able to define a unique security code for radio products and site equipment. In the event that the codes do not match, calls will not be received or sent between the two.

Interoperability and Compatibility

In emergency situations that require immediate interoperability, the ESK function can be temporarily disabled by the Communications System Director (CSD) to allow communications with EDACS radios that do not support ESK or have a different ESK stored.

Setting Authorization


All radios within an Integrated Multisite and Console Controller (IMC) region must have the ESK feature enabled with the correct programming in order to be utilized in that region. Once the CSD activates the ESK feature, any radios with incorrect programming are not able to receive or transmit calls.

The EDACS ESK feature is compatible with the following products:

  • Portables – LPE-200, M-RK and Jaguar
  • Mobiles – EDACS 500M, Orion and Jaguar
  • Site equipment – SitePro/Site Interface Module (SIM) or GETC/Site Controller
  • Network equipment – Communications System Director (CSD)

How does ESK work?

For those of you that are not familiar with the EDACS control channel, it is broken down into a number of frames. Each frame is preceded by a specific command word, which identifies to the receiver what the purpose of the frame is. With EDACS system key, this command word has been XOR'd with a specific 8 bit value.

ESK Frame
0101110101001100 000100000001     5D4c 101
|      |   |   | |     |    |
|      |   |   | |     |----|---- System ID                (normal)   
|      |   |---|-|----------|---- Data Channel LCN (9-12)  (normal)
|      ||-|----|-|----------|---- Status Bits              (normal)
|------|-------|-|----------|---- Command Word (1-8)       (XOR)
|              | |          |
|----msg 1a----| |--msg 1b--|     ESK FRAME Site 01 LCN #12
1234567890123456 123456789012 

Thus, reversing the simple XOR to the expected value for common command words results in a value of "A0", which is the value that the command words are XOR'd with.