dajoh's CrackMe3 - Security by obscurity and amateur crypto

Author:
dajoh

Language:
C/C++

Upload:
2021-02-20 22:24

Download

Platform:
Windows

Difficulty:
4.0

Quality:
4.0

Arch:
x86

Downloads:
23

Size:
116.66 KB

Writeups:
0

Comments:
4

Description

Security by obscurity and amateur crypto, what could go wrong? This CrackMe includes various anti-debugging tricks and the code has been obfuscated. If you solve this CrackMe post the flag instead of the password.

Comments (4)
Writeups (0)

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4epuxa on 2021-03-10 19:27: I reversed your crackme, as I understand it uses the generation of the crc table, there is also a xor of a hard-coded table with our password, the size of the table is 0x00012800, which is 75 776 in decimal. Then the crc table is generated, which is then used at the very end before checking our hash ... It was similar to the crc32 algorithm. Accordingly, I cannot reverse algorithm because it is one-way hash function, I need to brute-force it. The biggest problem is that there is no exact number of characters, so brute-force can take about 10,000,000 years. Crackme has no solution. The author, if I am wrong, correct me.

Towel on 2021-03-10 20:42: @4epuxa The CRC32 algorithm is not a cryptographic hash algorithm and can be easily abused and manipulated to craft given hashes, specific inputs, or even both. I'll leave that as an exercise to the reader. Here's a quick example you can verify yourself: $ crc32

Towel on 2021-03-10 20:42: $ crc32

Towel on 2021-03-10 20:44: CM1 is filtering my other comments, so they weren't displaying properly. Here's a pastebin: https[:]//pastebin[.]com/raw/d0YXuydF

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dajoh's CrackMe3 - Security by obscurity and amateur crypto