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Old 11-26-2018, 06:44 AM   #1
qrange
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guess CRC32 algo


Is there a way to 'guess' the used algorithm (CRC parameters)?

I have data and the expected checksum value, but I'm not sure if it really is CRC.

Would like Jacksum or similar to try all common algorithms if there is no 'shortcut'.

Thanks.

Last edited by qrange; 11-26-2018 at 06:51 AM.
 
Old 11-26-2018, 07:27 AM   #2
ehartman
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Quote:
Originally Posted by qrange View Post
Is there a way to 'guess' the used algorithm (CRC parameters)?

I have data and the expected checksum value, but I'm not sure if it really is CRC.

Would like Jacksum or similar to try all common algorithms if there is no 'shortcut'.

Thanks.
CRC32 is 4 bytes (32-bits) so 8 hex digits. Other algorithmns normally have a different (larger) number of digits (i.e. MD5 has 32). Even the old DES encryption normally already had 11 digits. So with 8 ones you can safely gues it is CRC32 (and with 4 digits CRC16).
 
Old 12-07-2018, 09:23 AM   #3
ntubski
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Reverse-Engineering a CRC Algorithm

But it's probably worth just guessing and checking a couple of the most common crc parameter combinations first.
 
  


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