|
|
|
|
|
|
|
Motorola
Digital Voice Protection
Digital Voice Protection, abbreviated DVP, 1 is a proprietary self-synchronising algorithm
for the encryption and decryption of voice communication,
developed in the 1970s by Motorola Inc.
in Chicago (Illinois, USA). The algorithm was internally known at
Motorola
by the codename VULCAN [1]. The name 'DVP' refers to both the VULCAN
algorithm and the equipment that incorporates it.
DVP (VULCAN) typically works with a 12 kb/s bitstream from
a continuous variable slope delta modulation (CVSD) digitiser.
The cipher is basically a Ciphertext Auto Key (CTAK), also known as
Cipher Feedback (CFB) or autoclave.
Although it has nonlinear properties, the shift-register-based algorithm is
basically a linear one.
Encryption and decryption takes place in a custom chip
marked SC76807.
For encoding and decoding CVSD, Motorola used a custom CMOS
integrated circuit (IC), codenamed BUTTERSCOTCH [1].
|
|
DVP was succeeded in the late 1980s by DVP-XL,
which is not based on the VULCAN algorithm.
Instead it uses the improved LINUS algorithm
plus a clever technique — internally known as REX 2 — which converts the
1-bit CTAK block cipher into a kind of counter addressing mode.
The addition of REX — denoted by the suffix 'XL' — makes the device less
prone to error propagation, especially near the edge of the device's range.
It is described in US Patent 4,893,339 [3].
|
-
Registered trademark of Motorola Inc.
-
REX is a diminutive of Range Extension.
|
|
|
DVP equipment on this website
|
|
|
In 2014, Cornelius, Jenkins and Riddler reverse engineered the
SC76807 custom-developed cryptographic chip and the firmware of the
T-3010 key loader, and came to the conclusion that the algorithm
is notoriously weak, even by the standards of the 1970s.
They managed to simulate the algorithm in software and proved that it could
be broken in realtime with simple methods.
It seems likely that the algorithm was deliberately weakened in oder to
obtain an export licence.
➤ Description and analysis of the VULCAN algorithm
|
|
|
|
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?
© Crypto Museum. Created: Monday 22 August 2022. Last changed: Monday, 22 August 2022 - 14:03 CET.
|
 |
|
|
|
