E.F. Johnson Company 53SL ES Series Operating Manual page 148

Over-the-Air Rekeying (OTAR) Section 8 - Secure Communication (Encryption)
Keyset Changeover - The process used to switch the active keyset setting on a subscriber
unit to the currently inactive keyset so that the keys in the newly inactive keyset can be
replaced without interrupting encrypted communication.
Key Loader - Any type of device used to load encryption keys into a radio. With OTAR,
this device must be used to provide the initial key loading of a subscriber unit so that it
contains the basic keys needed for OTAR by the KMF. If OTAR is not used, it is always
used to load encryption keys. All keys stored in the key loader are themselves encrypted.
EFJohnson Technologies offers a PDA-based keyloader.
Logical Link ID (LLID) - An ID transmitted with a CAI data message to identify the
destination of the message.
Message Number Period (MNP) - The maximum difference between message numbers
that can occur before a message is declared invalid (see Section 8.5.4).
Over-The-Air-Rekeying (OTAR) - The process of sending new encryption keys over the
air using an RF interface.
Red - Refers to information that is not encrypted. The opposite is "Black".
Rekey - The process of preparing, sending, and loading encryption keys into a subscriber
unit for current or future use. This may be done over-the-air (OTAR) or by directly
connecting a keyloader to the subscriber unit.
Radio Set Identifier (RSI) - Subscriber units are programmed with one or two Radio Set
Identifier (RSI) numbers that identify the unit for OTAR purposes. The RSI can be unique
to an individual subscriber unit or unique to a group of subscriber units. An individual
(unit) RSI is always assigned and a RSI may be assigned. The individual RSI is typically
programmed when the subscriber unit is initially brought into service. The KMF is also
identified by an RSI (KMFRSI) to use as the destination of any KMMs a subscriber unit
originates. The KMMs (Key Management Messages) generated by the KMF (Key
Management Facility) are addressed to a specific RSI.
Storage Location Number (SLN) - A link to a TEK in a given keyset. A given SLN can
contain two keys, one for the active keyset and one for the inactive keyset. SLNs and
CKRs are equivalent terms (see Section 8.2).
Traffic Encryption Key (TEK) - A key used to encrypt voice or data. The other type of
key is the Key Encryption Key (KEK) which is used to encrypt keys contained in Key
Management Messages. TEKs can be either the DES type.
Unique Key Encryption Key (UKEK) - A KEK unique to a particular subscriber unit.
Refer to "KEK" for more information. These keys can be either the DES type.
Zeroize - The process of deleting all keys from a compromised subscriber unit to disable
it. To make the unit encryptionally functional again, the keys must be reloaded by a
keyloader.
8-14 53SL ES Series Mobile Radio Operating Manual April 2009