Re: CHECKSUM CHALLENGE - (US$ 100)

From: Rene Tschaggelar (none_at_none.net)
Date: 02/11/04


Date: Wed, 11 Feb 2004 21:07:38 +0100

Carlos Gomez wrote:

> CHECKSUM CHALLENGE
>
> We're offering US$100 to have a checksum/CRC algorithm
> reverse-engineered.
>
> We have a microcontroller-based system that connects via modem to a
> remote PC. The PC runs a software that talks to the microcontroller,
> sending and receiving data. The person that developed this system for
> us is no longer available.
> We have the protocol to control the system but we don't know the
> checksum algorithm and therefore can't get the new data accepted by
> the receiving machine.
> Apparently the last two bytes of each data packet are Checksum/CRC.
> The first byte is the number of bytes that follows in the packet (we
> don't know if this byte is computed in the Checksum/CRC).
>
> Examples of the data and resultant checksum are provided below.
>
> If interested, please email me for further details. I will let you
> know how many others have applied. The money goes to the first one who
> returns a working algorithm preferably implemented in VB.
>
> Thanks,
>
> Carlos Gomez
> carlos_gomez_73@hotmail.com
>
> 06 FF 01 FF 09 FF 46 FF 36 FF D8 FF F5
> 06 FF 01 FF 09 FF 0A FF 3C FF F1 FF 95
> 06 FF 01 FF 09 FF 7C FF 2A FF E0 FF A3
> 06 FF 01 FF 09 FF A6 FF 36 FF D8 FF C1
> 06 FF 01 FF 09 FF D6 FF 2A FF DE FF 5B
> 06 FF 01 FF 07 FF 06 FF 1E FF 7D FF D7
> 06 FF 01 FF 07 FF 24 FF F5 FF 23 FF 91
> 06 FF 01 FF 08 FF 80 FF 1E FF 22 FF 9D
> 06 FF 01 FF 08 FF 9E FF 42 FF 72 FF C1

Did you try to look at a packet as :
06 01 09 46 36 D8 F5

Rene

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