Thread: Reverse CRC ...
View Single Post
Old 01-14-2020, 03:11
chants chants is online now
Join Date: Jul 2016
Posts: 515
Rept. Given: 5
Rept. Rcvd 34 Times in 20 Posts
Thanks Given: 434
Thanks Rcvd at 779 Times in 361 Posts
chants Reputation: 34
I think identification of CRC algorithm is a better description. Reversing a compression function in the mathematical sense is simply not possible unless there are trapdoors or biases and the like. But in the reverse engineering context I think we can imply as such.

Have you tried all CRC16 possibilities on this page in Javascript?

Considering it could be a truncated CRC32 or CRC64 or concatenated CRC8 of subpieces or a custom CRC, it is somewhat hard to say. If its based off a polynomial may e there is a way to find it but I've not seen a technique for this but it sounds promising. Otherwise you may need to see if you can white box reverse this.

I doubt glancing at what seem to be CRC16 type values will be trivially obvious to anyone though
Reply With Quote