User's Manual

Draft 02 - Sep 1 2015
Viking Mobile Radio Operating Manual 7-3
Secure Communication (Encryption)
7.2 Encryption Keys
An encryption key is a cryptographic variable that is required by the encryption algorithm
to encrypt and decrypt voice or data. To maintain system security, these keys must be
protected from disclosure and also periodically replaced or updated.
With the AES and DES hardware encryption and ARC4 software encryption used by
EFJohnson Technologies radios (see Section 7.1), the same encryption key is used by both
the encrypting (sending) and decrypting (receiving) radio. AES encryption keys are
generated from a string of 64 hexadecimal characters, and DES keys are generated from a
string of 16 hexadecimal characters. Another four hexadecimal characters are used to
specify the key ID. Multiple keys can be loaded into a radio using OTAR or manual
loading. ARC4 software encryption keys are generated from a string of 10 hexadecimal
characters. Multiple keys can be loaded into a radio using Armada.
If an attempt is made to transmit a secure message without loading the corresponding key,
“KEYFAIL” is displayed. The message must then be transmitted in the clear mode (this is
possible only if the channel is strapped to “switchable”) or the key must be loaded.
7.2.1 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.