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Help with possible crc16


 

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Author Message
vesko_hard
New User



Joined: 18 Mar 2014
Posts: 2


Mar 18, 2014 7:53 am

Hi,
i have problem with data checksumm, i think its CRC16 .

Here is examle data:

$31$4B$30$30$33$35$32$37$34$42$00$00$00$00($E8$F8)
E8_F8 is checksumm

Here is another packet:
$33$43$30$30$33$35$32$37$39$00$00$00$00$00($D8$1E)

I try to use revend, but without success(maybe i dont understand all of its features).
Its possible to find(brutr-force) algo(parameteres) with reveng.
Any help is wellcome.

Thanks in advance.
Gammatester
Guest







Mar 19, 2014 7:35 am

SRP16 gives two possible parameter sets for the polynomial $1021
Code:

===== Result parameter sets =====
CRC=$f8e8  Poly=$1021  init=$0002  xorout=$0000  refin=false  refout=false
 *** Second data set verified
CRC=$f8e8  Poly=$1021  init=$f0a7  xorout=$ffff  refin=false  refout=false
 *** Second data set verified===== done =====
I prefer the set with xorout=$0000 because it is closely related to the XModem/ZModem algorithm. In fact you can directly use Lammert's online calculator with XModem for your problem if you prefix your bytes with $2a $c3:
Code:
"2ac3314B303033353237344200000000" (hex)
1 byte checksum   16
...
CRC-CCITT (XModem)   0xF8E8
Hope that helps
Gammatester

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