Name: Decypher

Text: btt - Decypher
BTT Decipher provides A5/2 Decryption Algorithm.
The over-the-air privacy of GSM telephone conversations is protected by theA5 stream
cipher. A5/2 version is used by 100s of millions customers in many countries, with A5/2
decoding product we supply a way to decipher A5/2 and extract the conversation key in
less than a second.
Each GSM phone conversation can be encrypted by a new session key K,which is
derived in a noninvertible way from the user's master key and a random value by another
algorithm known as A8. By having some part of the traffic our A5/2 decoder is able to
output the key.
Law enforcement agencies, public protection organisations that utilize GSM receiver
can have A5/2 decypher unit to be incorporated into their receivers to enable them
monitor the target phone conversation.

11001101
10111011
10111001
11001101
11100110
10101101

btt bilgi teknoloji tasarım ltd.
www.btt-int.com

*Documents subject to change without notice!

Customisation and development services are available upon request.

btt - Decypher
Specifications:

Description and Capabilities:
The A52 decipher is expected to run as a single application on a Single Board
Computer(S.B.C).
The A52 decipher board offers Kc extraction from SDCCH bursts.
Input to the extraction unit is 8 consecutive SDCCH/8 bursts or 12 consecutive
SDCCH/4 bursts.
Output is 8 bytes of Kc.

Performance:
Current implementation is based on a Pentium-m processor, clocked at 1.8GHz with
2GBytes of RAM. Disk usage is 20GBytes;
Average response time is 25mSec. Max response time is 60mSec.

Minimum Requirements:
- Dedicated SBC
- 2 GBytes RAM
- 20 GBytes disk space
- Operating System Windows XP Pro SP2
Usage:

#define MSG_TYPE_DCU_KC

0x00000002

struct SDCUKey {DWORD MsgType; int Dmu; int SessionID; UINT64 Kc; DWORD TimeToFindKey; };
#define MSG_TYPE_DCU_BURSTS

0x00000003

struct SDCUBursts {DWORD MsgType; int Dmu; int SessionID; int NumBursts;
DWORD *FrameNumbers, BYTE *BurstData};

btt bilgi teknoloji tasarım ltd.
www.btt-int.com

*Documents subject to change without notice!

The board uses the GTCPLib communication library as an interface. The protocol is
described using the C++ code below :

Document Path: ["180-btt-bilgi-teknoloji-tasarim-brochure-decypher.pdf"]

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