Figure 3-10. Traffic Decryption Key Negotiation - Comtech EF Data DMD-2050E Installation And Operation Manual

DMD2050E Universal Satellite Modem
Lynyx sets everyone up to start the
decryption process, the TRANSEC
FPGA initiates based on SOF and
TEK Update message (Key Roll)
Event: KA Message Received
Action: Resend KAR Message,
Compute TEK Load TEK
MN-DMD2050E Revision 2
Startup
Event: Key Agreement Message (KA) Received
Action: Create Key Agreement Response (KAR) Message, Send KAR Message,
Compute TDK, Load TDK
Waiting for
Event: Key Rollover
Action: None
Waiting for
Event: One good Frame
Action: None
Does Crypto loose sync on every key
Decrypting
rollover? How to we initiate the roll
without sync loss event
Event: N Bad Frames or Loss of Demod Sync or Loss of IF Lock
Action: Zeroize TEK, Send RX Sync Lost Message

Figure 3-10. Traffic Decryption Key Negotiation

MnC needs to mail the overriding
state of the decryption to the FIPs
may not be enabvled
Event: KA Received, Encryption Not Enabled
Idle
Action: Send Key Agreement NACK
Key
Rollover
Crypto
Event: Loss of Demod Sync or Loss of IF Lock
Sync
Action: Zeroize TEK, Send RX Sync Lost
Message
TRANSEC FPGA will clear its N Bad
frame counter after the first good
frame is ID'd
Crypto
Sync Lost
EVENT: Timeout
Action Back to Idle
We'll need a user defined timeout
Theory of Operation
Lynyx sets everyone up to start the
decryption process, the TRANSEC
FPGA initiates based on SOF and
TEK Update message (Key Roll)
3–23