Comtech EF Data DMD-2050E - Manual (Page 65)

DMD2050E Universal Satellite Modem Theory of Operation
MN-DMD2050E Revision 2 3–23
Idle
Waiting for
Key
Rollover
Startup
Event: Key Agreement Message (KA) Received
Action: Create Key Agreement Response (KAR) Message, Send KAR Message,
Compute TDK, Load TDK
Waiting for
Crypto
Sync
Event: Key Rollover
Action: None
Decrypting
Event: One good Frame
Action: None
Crypto
Sync Lost
Event: N Bad Frames or Loss of Demod Sync or Loss of IF Lock
Action: Zeroize TEK, Send RX Sync Lost Message
Event: KA Message Received
Action: Resend KAR Message,
Compute TEK Load TEK
Event: Loss of Demod Sync or Loss of IF Lock
Action: Zeroize TEK, Send RX Sync Lost
Message
Event: KA Received, Encryption Not Enabled
Action: Send Key Agreement NACK
MnC needs to mail the overriding
state of the decryption to the FIPs
may not be enabvled
Lynyx sets everyone up to start the
decryption process, the TRANSEC
FPGA initiates based on SOF and
TEK Update message (Key Roll)
Lynyx sets everyone up to start the
decryption process, the TRANSEC
FPGA initiates based on SOF and
TEK Update message (Key Roll)
TRANSEC FPGA will clear its N Bad
frame counter after the first good
frame is ID’d
Does Crypto loose sync on every key
rollover? How to we initiate the roll
without sync loss event
EVENT: Timeout
Action Back to Idle
We’ll need a user defined timeout
Figure 3-10. Traffic Decryption Key Negotiation