help trying to reverse engineer CRC algorithm
- From: mramirez <manologab@xxxxxxxxx>
- Date: Fri, 4 Jul 2008 13:16:27 -0700 (PDT)
Hi,
This a protocol I'm trying to implement but I can't figure out what's
the
CRC algorithm used (assuming that it's indeed a CRC).
Here are some captures, I included those that I consider more helpful.
This packages are all 136 bytes long, all the .... are filled with
0x00,
each line is a diferent packet except the last one.
26 00 00 00 .... 00 AD D2 7E
26 05 00 00 .... 00 2A 24 7E
26 04 00 00 .... 00 0B BA 7E
26 20 00 00 .... 00 AE 8F 7E
26 21 00 00 .... 00 8F 11 7E
26 22 00 00 .... 00 FD BB 7E
26 23 00 00 .... 00 DC 25 7E
26 24 00 00 .... 00 08 E7 7E
26 28 00 00 .... 00 E2 5E 7E
26 02 01 00 .... 00 C4 1E 7E
27 43 02 15 38 30 39 33 30 37 36 35 35 30 40 61 6C 6C 74 65 6C 2E 6E
65\
74 00 .... 00 16 07 7E
There are other packages of different lengths also.
41 30 30 30 30 30 30 DF 8A 7E
41 01 70 41 7E
29 01 00 31 40 7E
I tried to apply the method described here:
http://www.derkeiler.com/Newsgroups/sci.crypt/2006-05/msg01205.html
with the 26 2x packets, but I got an strange result:
26 00 = ADD2
26 20 = AE8F
26 21 = 8F11
26 22 = FDBB
26 24 = 08E7
26 28 = E25E
AE8F^8F11=219E
AE8F^FDBB=5334
AE8F^08E7=A668
AE8F^E25E=4CD1
219E*2 ^ 5334 = 1008
5334*2 ^ A668 = 0
A668*2 ^ 4CD1 = 10001
It feels like I'm almost there but I must be missing something
obvious.
Any ideas?
Thanks in advance.
Manolo Ramirez T.
.
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