Title: Cyclic Redundancy Chase
Brought to you by horst35
Thanks and cheers to horst35!
Is there a misprint in the python code?
Should len(b) really be len(s)?
Yes, you are right, of course.
Sphinx, can you please change that?
Fixed.
The connection between 1/59 and 5/28 was clear, but I have not been able to make this method work for 5/28.\
Also, a different (in appearance) approach also fails on 5/28. Either I keep making the same error each \
time or the following two lines are mutually inconsistent:
crc(sol, 0xFADED) = 0x5B21B
crc(sol, 0xC0DEBAD) = 0x54905E
Could this be another misprint?
I will check this when I have access to my code later. If this indeed another bug, I will be very frustrated with myself as I triple checked each checksum, and simultaneously very sorry for your loss of time so far. For your sake, I hope that you implemented your approach as a computer program so that you don't have to invest the same amount of time again.
EDIT: Yes, you are correct again. It should be C0D3BAD instead of CODEBAD. I can't believe this mistake actually crept in. Sphinx can please fix this new single letter bug?
My next idea was to exhaust over all one character misprints for 0xFADED and 0xC0DEBAD, but due to my fixation on where I thought the misprint was, I would have only tried to correct the crc values, not the poly.
Yes, my work was by computer, with four implementations of the "blackout" idea and one totally different idea. My MacBookPro is glad for the work, but I eventually get frustrated. Don't even ask how long I fought with the RSA problem because of a trivial bug at the very end that prevented the correct answer from being printed.
BTW: Thanks for doing the work of creating and posting problems. Myself, I'd be too terrified that I would make some trivial error in the posting. :)
Fixed.
Can anyone have a code to verify the crc values are correct?
I believe that my code is working but I couldn't find a solution that fit the conditions. can I pm anyone in the matter maybe?
I get server connection timeout whenever I submit a correct solution... Does it mean this problem has broken?
Just checked. Works perfectly.
I am really frustrated by this challenge level.
I believe I know the math necessary for this challenge.
I've been coding a 400 line code in python for the past week in order to solve it (including tests).
My program is able to crack solutions with exactly the same arguments (but different crc outputs) which I feed them, in a matter of a second if it is up to 13-14 characters.
It can also crack passwords up to 16 characters in about two hours (slow python execution). The ONLY thing I assume on solutions longer than 14 characters is that their ASCII values are up to 127 (otherwise, there are practically endless number of solutions).
I've tested my program on my own secret phrases evaluated CRCs and it succeeds every time!
Nevertheless, when I run it on the challenge inputs, it cracks outputs which have non-printable characters.
Can someone please verify that my implementation of the crc function (as supplied in this challenge) is actually correct. If it's not, it will explain where I started wrong.
>>> crc('hc PdYZv#m0x', 0xDEAD)
26991
>>> crc('hc PdYZv#m0x', 0xF00D)
30431
>>> crc('hc PdYZv#m0x', 0xFADED)
505961
>>> crc('hc PdYZv#m0x', 0xC0D3BAD)
20612737
>>> crc('hc PdYZv#m0x', 0xFACADE13)
1786503438
Are these the actual crc outputs? Such outputs are cracked by my program in seconds.
Are these correct: ?
>>> crc('?F$e;#6VrZi8wYa2', 0xDEAD)
1323
>>> crc('?F$e;#6VrZi8wYa2', 0xF00D)
22874
>>> crc('?F$e;#6VrZi8wYa2', 0xFADED)
292312
>>> crc('?F$e;#6VrZi8wYa2', 0xC0D3BAD)
14757065
>>> crc('?F$e;#6VrZi8wYa2', 0xFACADE13)
264014396
Once again. My program can even crack this in two hours.
And yet, when I try the numbers in the actual challenge, nothing comes out... This is so frustrating...
Please let me know if my evaluated crc signatures are correct.