Author's details

Date registered: September 14, 2010

Latest posts

  1. 0CTF 2018 Quals – zer0C5 (Crypto 785) — April 2, 2018
  2. 0CTF 2018 Quals – zer0SPN (Crypto 550) — April 2, 2018
  3. 0CTF 2018 Quals – zer0TC (Crypto 916) — April 2, 2018
  4. TWCTF 2017 – Solutions for BabyPinhole, Liar’s Trap, Palindrome Pairs Challenge — September 4, 2017
  5. Polictf 2017 – Lucky Consecutive Guessing (Crypto) — July 9, 2017

Most commented posts

  1. Codegate 2014 Quals – Minibomb (pwn 400) — 12 comments
  2. Codegate 2014 Quals – Angry Doraemon (pwn 250) — 9 comments
  3. Hack.lu 2012 CTF Challenge #14-15 (150+250) — 8 comments
  4. Hack.lu 2012 CTF Challenge #17 (400) — 7 comments
  5. Leet More 2010 Time Traveller writeup — 6 comments

Author's posts listings


0CTF 2018 Quals – zer0C5 (Crypto 785)

0ops Cipher 4, hope you enjoy it:) zer0C4.zip nc 1234 Summary: related-key attack on weakened variant of RC4


0CTF 2018 Quals – zer0SPN (Crypto 550)

0ops SPN, hope you enjoy it:) zer0SPN.zip Summary: linear cryptanalysis on toy block cipher


0CTF 2018 Quals – zer0TC (Crypto 916)

0ops Toy Cipher, hope you enjoy it:) zer0TC.zip Summary: meet-in-the-middle and key-schedule constraints


TWCTF 2017 – Solutions for BabyPinhole, Liar’s Trap, Palindrome Pairs Challenge

Scripts with short explanations: BabyPinhole (crypto 163) Liar’s Trap (crypto/ppc 281) Palindrome Pairs – Challenge Phase (ppc 63+337)


Polictf 2017 – Lucky Consecutive Guessing (Crypto)

We implemented a random number generator. We’ve heard that rand()’s 32 bit seeds can be easily cracked, so we stayed on the safe side. nc lucky.chall.polictf.it 31337 chall.py Summary: breaking truncated-to-MSB LCG with top-down bit-by-bit search.


Google CTF 2017 Quals – BLT (Bleichenbacher’s Lattice Task – Insanity Check)

A slow descent into the dark, into madness, futility, and despair. BLT.jar (not necessary) STDOUT Flag.java Summary: DSA with short secrets, lattice + meet-in-the-middle attack.


Google CTF 2017 Quals – Crypto writeups

Scripts with short explanations for all crypto tasks (except RSA) from Google CTF Quals 2017: Crypto Backdoor Introspective CRC Shake It RSA CTF Challenge (no writeup, but I think it’s similar to this old one) Rubik Bleichenbacher’s Lattice Task (full writeup here)


0CTF 2017 Quals – Zer0llvm

Talent Yang loves to customize his own obfuscator. Unfortunately, he lost his seed when he was watching Arsenal’s UEFA game. What a sad day! His team and his seed were lost together. To save him, could you help him to get back his seed? We can not save the game, but we may be able… Continue reading »


0CTF 2017 Quals – OneTimePad 1 and 2

I swear that the safest cryptosystem is used to encrypt the secret! oneTimePad.zip Well, maybe the previous one is too simple. So I designed the ultimate one to protect the top secret! oneTimePad2.zip Summary: breaking a linear and an LCG-style exponential PRNGs.


33C3 CTF 2016 – beeblebrox (Crypto 350)

Make bad politicians resign! nc 2048 files Summary: factorization-based attack on a signature method


HITCON CTF QUALS 2016 – Reverse (Reverse + PPC 500)

At least our ETA is better than M$. http://xkcd.com/612/ reverse.bin Summary: optimizing an algorithm using Treap data structure and CRC32 properties.


HITCON CTF QUALS 2016 – PAKE / PAKE++ (Crypto 250 + 150)

pake1.rb pake2.rb Summary: attacking password-based key exchange schemes based on SPEKE with MITM.


TUM CTF 2016 – Shaman (Crypto 500)

Oh great shaman! Somehow the village idiot got his hands on this fancy control machine controlling things. Obviously, we also want to control things (who wouldn’t?), so we reverse-engineered the code. Unfortunately, the machine is cryptographically protected against misuse. Could you please maybe spend a few seconds of your inestimably valuable time to break that… Continue reading »


TUM CTF 2016 – Tacos (Crypto 400)

All my fine arts and philosophy student friends claim discrete logarithms are hard. Prove them wrong. nc 1729 vuln_tacos.py Summary: bypassing Fermat primality test with Carmichael numbers and solving discrete logarithm using Pohlig-Hellman algorithm.


TUM CTF 2016 – ndis (Crypto 300)

We have a HTTPS server and client talking to each other with you right in the middle! The client essentially executes curl –cacert server.crt https://nsa.gov with some magic to redirect the transmitted data to your socket, to which the server responds with a lovely German-language poem. NOTE: There is nothing else hosted on the server;… Continue reading »

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