4-7 OTAR
Without OTAR, the operator has to collect all radios
and reprogram them to change the keys. Or a
technician must go around and visit all the radio
sites with a PC and a programmer just to change
keys – it is time-consuming.
OTAR or Over-The-Air-Rekeying is the common name
for the method of changing the encryption keys over
a radio channel or “over the air”. It is also referred to
as Over-the-Air Transfer (OTAT).
Regular key changing is one of the basic
In addition, without OTAR, it is very difficult or even
impossible to re-program the scramblers with a
wired programmer due to their big number and
distances of one from another.
OTAR solves all these problems - you can do without
reprogramming all the radios and visiting the radio
sites. You can easil
s or
requirements for secure radio communication. Key
changing can be achieved by reprogramming of
scramblers with a wired programmer or over the air.
Presently radio communication systems, secured by
scramblers, prefer to use the OTAR method of key
changing due to the following benefits.
change them over completely regardless of the
distance and big numbers.
To make the most of these benefits, leading
manufacturers of scramblers began to design
various methods of key changing over the air.
Many of the newer NSA (National Security Agency )
cryptosystems that use the 128
■Benefits from using OTAR
Brisk and efficient – these are the words to describe
the benefits from using OTAR.
zThe operator can change over the keys of many
radios at the same time regardless of the distance.
cryptosystems that use the 128
such as the ANDVT, KY-58, KG-84 A/C, and KY-75
are capable of obtaining new or updated key by
OTAR. All an operator would have to do is to observe
the alarm indications and ensure the alarm indicator
returns to operate. The electronic key would normally
come from the Net Control Station (NCS).
zThe keys which are consisted of big numbers can
be easily changed or updated without manual
programming.
zThe use of OTAR drastically reduces the
distribution of physical keying material and the
physical process of loading crypto equipments with
function. (OTAR function became available from the
firmware Rev.1.40 on.)
nothing to do with actual physical CRYPTO
changeovers on a day-to-day basis.
The dispatcher
Old key New key
Update or change Electronic
keys remotely
the operator to update the current
electronic keys or change them over with
the new keys remotely.
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