|
|
|
|
|
|
|
← Racal Phone
Secure phone adapter
MA-4471 is secure telephone adapter,
developed around 1996 by
Racal COMSEC Ltd in Salisbury (Wiltshire, UK).
It is intended for analogue (PSTN) telephone sets, and allows them to make
secure calls over insecure networks. The MA-4471 is based
on the military voice encryptor MA-4470.
|
The image on the right shows the MA-4471 with its sloped control panel at
the front. The top surface of the unit is large enough to place a standard
telephone set on. All controls are accessible from the front.
At the rear, the MA-4471 has only three connections: one for the power
supply unit, one for the phone and one for connection to the telephone line.
The unit is clearly designed exclusively for the UK market, as it features
the proprietary British phone connectors, rather than the more common
modular jacks.
|
|
|
The MA-4471 communicates with the user via a small LCD display at the
front. To the left of the display are two coloured buttons to select
between CLEAR and SECURE speech.
To the right of the display is a small numerical keypad with the digits
0-9. Additional keys are hidden behind a small panel at the right.
These keys are used when entering the cryptographic key(s).
Also behind the panel is a 5-pin Fisher socket for the connection of a
key fill device, as an alternative to entering keys manually.
|
At present, we have no further information about this device.
If you know more, or if you happen to have a manual for this unit,
please contact us.
It is unclear whether the MA-4471 has been distributed widely and whether
they are still in use today.
As the MA-4471 was introduced just before Racal was taken over by Thomson
(now Thales) it is quite possible that this has prevented a wide-spread
roll-out.
|
After opening the unit, it becomes clear that the MA-4471 is not TEMPEST compliant. The two PCBs, a digital board
and an analog board,
are placed inside a plastic unshielded case.
Furthermore, the entire encryption is carried out in firmware and there are
no anti-tamper provisions, suggesting that this device was only intended for
medium-grade encryption.
|
The image on the right shows the 8-bit Toshiba AMPZ84C00 processor that is
running here at 6 MHz. Aside the processor are two 8 KB static RAM chips
(TC5564) and an EEPROM. Encryption takes place completely in the digital
domain.
The CPU (the digital board) is nearly identical to that of the
military MA-4470. The same 8-bit processor and peripheral
ICs are used and the controls are also very similar.
The main difference is in the analog circuitry.
The audio in/out circuitry and the telephone line interface are both on the
so-called analog board.
|
|
|
The MA-4471 was clearly designed for the UK market, as it is wired for the UK
telehone network. There is no reason why it shouldn't work in another country
though, provided that proper conversion cables or plugs are used.
|
-
Document kindly provided by Anastasios Pingios. May 2021.
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Tuesday 14 September 2010. Last changed: Tuesday, 04 May 2021 - 16:18 CET.
|
 |
|
|
|
