Google CTF – Woodman (Crypto 100)

How honest are you? Running here Summary: breaking a weak PRNG

25 2013 CTF – Crypto 350 (BREW’r’Y)

BREW’r’Y (Category: Crypto) Author(s): dwuid Finally, the robots managed to sneak into one of our breweries. I guess I won’t have to explain how bad that really is. That darn non-physical ones even shutdown our login system. Shiny thing, advanced technology, all based on fingerprints. Been secure as hell. If only it was running. Well,… Continue reading »


PoliCTF 2012 Crypto 200

This is an OpenCL binary. Go! opencl.bin Summary: xor and xor


SIMD [250] (Pirating)

After examining some code retrieved by our operative we are unsure whether it was written by an evil genius or a google employee. We will let you decide. Summary: linux x64 binary, obfuscated xor


NuitDuHack 2012 Prequals – executable1.ndh

Meanwhile, we got fresh news from our mystery guy. He came along with an intersting binary file. It just looks like an executable, but it is not ELF nor anything our experts would happen to know or recognize. Some of them we quite impressed by your skills and do think you may be able to… Continue reading »


NuitDuHack 2012 Prequals – executable2.ndh

Our anonymous guy managed to get access to another bunch of files. We also need to get as much information as possible about the file itself. If you succeed, you will be rewarded with $2500 for the ndh file. executable2.ndh NDH Virtual Machine Summary: VM in the NDH VM, crackme


CodeGate 2012 Quals Forensic 500 Write-up

This file is Forensic file format which is generally used. Check the information of imaged DISK, find the GUIDs of every partition. Answer: strupr((part1_GUID) XOR (part2_GUID) XOR …) Download : B704361ACF90390C17F6103DF4811E2D Forensic 500 features EWF format container with EFI GPT partition table.


Gits 2012 #19 – Crypto 250

Question: SuperSecure 250 Points Use your team name and generate a valid answer. (File) Summary: xor-chained sha256 and sha512


MozillaCTF 2012 SecureFileLock (250) Writeup

This very secure locking mechanism encloses files and only gives them to you when you know the passphrase. Find it and you will have the flag. Category: reversing Summary: find out a xor cipher, use xortool to get the key

21 CTF 2011 Simplexor (200)

Category: crypto To get a better security we deceided to encrypt our most secret document with the secure xor-algorithm. Unfortunately we lost the key. Now we are sad. Can you help us recovering the key? Download Summary: recovering multibyte xor-key, using autocorrelation


Codegate CTF 2011 Mini writeups

Some mini writeups on Codegate 2011 Prequals: Issue100,200, Net100,200, Crypto100,200.