My Writeups / Challenge Solutions
Here I have collected links to my writeups/solutions for challenges from various competitions (mainly Capture The Flag). The main topic is cryptography, but some others are covered too: reverse-engineering, exploitation of memory corruption bugs, sandbox escapes, steganography, etc.
The most interesting from my point of view are marked as .
2024
idekCTF 2024
- summertime (writeup) :: crypto/codes
CodegateCTF 2024 Preliminary
- Babylogin (writeup) :: crypto/elliptic
- DatingGame (writeup) :: crypto/AES-GCM
- FactorGame (code) :: crypto/RSA
- LACUCARA_VM (code) :: crypto/linear
2023
corCTF 2023
- Superbox (writeup) :: crypto/block-cipher, crypto/DDT, crypto/S-box
- Oil-Spill (writeup) :: crypto/multivariate, crypto/LLL, crypto/linear
2022
CodegateCTF 2022
- Happy S-box (writeup) :: crypto/linear, crypto/LFSR, crypto/cube, crypto/integral
- Prime Generator (writeup) :: crypto/RSA, crypto/primes, crypto/small-roots
TetCTF 2022
- shares (writeup) :: crypto/linear, crypto/secret-sharing
- shares2 (writeup) :: crypto/linear, crypto/secret-sharing, crypto/LLL
- algebra (writeup) :: crypto/elliptic
- fault (writeup) :: crypto/RSA, crypto/fault, crypto/LLL
2021
Dragon CTF 2021
- CRC recursive warmup+hard (writeup) :: crypto/linear, crypto/nonlinear, crypto/CRC
Zer0pts CTF 2021
- wa(rsa)mup (writeup) :: crypto/RSA
- OT or NOT OT (writeup) :: crypto/discrete-log, crypto/oblivious-transfer
- easy pseudo random (writeup) :: crypto/PRNG, crypto/small-roots, crypto/multivariate
- 3-AES (writeup) :: crypto/AES
- pure division (writeup) :: crypto/elliptic
- signme (writeup) :: crypto/PRNG, crypto/RSA, pwn, lang/C
- NOT Mordell primes (writeup) :: crypto/elliptic, crypto/RSA, crypto/multivariate
- Tokyo Network (writeup) :: quantum
Aero CTF 2021
2020
CONFidence CTF 2020 Finals
Crypto CTF 2nd
0CTF/TCTF 2020 Quals
RCTF 2020
- infantECC (writeup) :: crypto/elliptic, crypto/LLL, crypto/RSA
- MultipleMultiply (code) :: crypto/subset-sum, crypto/LLL, crypto/discrete-log
De1CTF 2020
- NLFSR (code) :: crypto/LFSR
- EasyRSA (code) :: crypto/RSA, crypto/small-roots
- Mini Pure Plus (writeup) :: crypto/block-cipher, crypto/integral
PlaidCTF 2020
- MPKC (code) :: crypto/MQ
Codegate 2020 Preliminary
- Munch (code) :: crypto/RSA, crypto/small-roots
- Polynomials (code) :: crypto/NTRU, crypto/LLL
2019
CTFZone 2019 Quals
- NTRU (code) :: crypto/NTRU
SECCON 2019 CTF Quals
- Crazy Repetition of Codes (writeup) :: crypto/CRC, crypto/linear
HITCON CTF 2019 Quals
- Randomly Select a Cat (writeup) :: crypto/RSA, crypto/LLL, crypto/approximate-GCD
- Lost Key Again (writeup) :: crypto/RSA, crypto/LLL
- Lost Modulus Again (writeup) :: crypto/RSA
- Very Simple Haskell (writeup) :: crypto/primes
Balsn CTF 2019
- pyshv1,2,3 (writeup) :: pyjail, pickle
- listcomp ppm (code) :: programming, golf, python
- collision (writeup) :: crypto/linear
- unpredictable (code) :: crypto/PRNG, crypto/MersenneTwister, crypto/linear
- harc4 (writeup) :: crypto/RC4
PwnThyBytes CTF 2019
- Wrong Ring (writeup) :: crypto/RingLWE
- LOTR (code) :: crypto/linear
- Avec (code) :: crypto/AES-GCM
- Primitive Obsession (code) :: reverse-engineering
- Unconventional (code) :: reverse-engineering
Crypto CTF 1st
- Midnight Moon (writeup) :: crypto/RSA
- Starving Parrot (writeup) :: crypto/RSA
- Olivier Twist (writeup) :: crypto/elliptic
SpamAndFlags Teaser 2019
- quadhash (code) :: crypto/hash
Midnight Sun CTF 2019 Quals
- open-gyckel-krypto (writeup) :: crypto/RSA
- tulpan (writeup) :: crypto/codes
0CTF/TCTF 2019 Quals
2018
NSUCRYPTO 2018
- Twin Peaks 2 (code) :: crypto/block-cipher
HITCON 2018
- Lost Key (code) :: crypto/RSA
- Lost Modulus (code) :: crypto/Paillier
Midnight Sun CTF 2018 Finals
0CTF/TCTF 2018 Quals
- zer0C5 (writeup) :: crypto/RC4
- zer0SPN (writeup) :: crypto/block-cipher, crypto/SPN
- zer0TC (writeup) :: crypto/block-cipher, crypto/SPN
- MathGame (code) :: misc, lang/C, printf, pwn
Codegate 2018 Preliminary
- RsaBaby (code) :: crypto/RSA
2017
NSUCRYPTO 2017
- FNV2 Hash (code) :: crypto/hash, crypto/LLL
TokyoWesterns CTF 3rd 2017
- BabyPinhole (writeup) :: crypto/Paillier
- Liar's Trap (writeup) :: crypto/secret-sharing, crypto/codes
- Palindrome Pairs - Challenge Phase (writeup) :: algorithms, crypto/hash, crypto/LLL
PoliCTF 2017
- Lucky Consecutive Guessing (writeup) :: crypto/PRNG, crypto/LCG, crypto/LLL
Google CTF 2017 Quals
- Bleichenbacher's Lattice Task - Insanity Check (writeup) :: crypto/LLL, crypto/DSA
- Crypto Backdoor (writeup) :: crypto/discrete-log
- Introspective CRC (code) :: crypto/linear, crypto/CRC
- Shake It (code) :: crypto/key-exchange, crypto/discrete-log
- Rubik (writeup) :: crypto/key-exchange, math
HITCON 2017 Quals
- Secret Server Revenge (writeup) :: crypto/MD5
0CTF/TCTF 2017 Quals
- zer0llvm (writeup) :: crypto/AES, crypto/block-cipher, reverse-engineering
- OneTimePad 1,2 (writeup) :: crypto/LCG, crypto/linear, crypto/PRNG
HXP CTF 2017
- FLEA (code) :: crypto/RSA
- 4ES (writeup) :: crypto/AES
- ouchenticated (writeup) :: crypto/AES, crypto/CRC
PlaidCTF 2017
- Common (code) :: crypto/RSA, crypto/LLL, crypto/small-roots
DEF CON CTF Qualifier 2017
- Godzilla (writeup) :: crypto/RSA, crypto/fault
ASIC CTF 2017 Finals
- Marijuana (writeup) :: crypto/LLL
Hack.lu CTF 2017
- McEliece (writeup) :: crypto/codes
2016
33C3 CTF
- beeblebrox (writeup) :: crypto/RSA, crypto/primes
HITCON CTF 2016 Quals
- reverse (writeup) +code :: algorithms, crypto/CRC, crypto/linear, reverse-engineering
- PAKE 1,2 (writeup) :: crypto/PAKE, crypto/man-in-the-middle
- RSA (code) :: crypto/RSA, crypto/fault
- Sharingan (code) :: misc, programming
- Beelzemon (code) :: programming, crypto/subset-sum
TUM CTF 2016
- shaman (writeup) :: crypto/hash, crypto/SHA1, crypto/secret-sharing, crypto/length-extension
- ndis (writeup) :: crypto/TLS, crypto/man-in-the-middle, crypto/AES-GCM
- tacos (writeup) :: crypto/primes, crypto/discrete-log
- hxphash (code) :: reverse-engineering, crypto/solvers
CSAW CTF Qualification Round 2016
- Broken Box (writeup) :: crypto/RSA, crypto/fault, crypto/small-roots
Tokyo Westerns/MMA CTF 2nd 2016
- Backdoored Crypto System (writeup) :: crypto/AES, crypto/block-cipher, reverse-engineering
- Pinhole Attak (writeup) :: crypto/RSA
Google CTF 2016 Quals
- Woodman (writeup) :: crypto/PRNG, crypto/LCG
- Spotted Wobbegong (writeup) :: crypto/RSA, crypto/PKCSv1.5
- Jekyll (writeup) :: crypto/hash
- Wolf Spider (writeup) :: crypto/hash, crypto/block-cipher, crypto/padding-oracle, crypto/length-extension
PlaidCTF 2016
- sexec (writeup) :: crypto/NTRU, crypto/LLL
- ratioactive (writeup) :: crypto/RSA, crypto/fault
0CTF 2016 Quals
- Equation (writeup) :: crypto/RSA
- RSA? (writeup) :: crypto/RSA
- Arsenal (code) :: crypto/AES
- (code) :: crypto/AES
Boston Key Party CTF 2016
- Feistel (writeup) :: crypto/block-cipher
- GCM (writeup) :: crypto/AES-GCM
- HMAC-CRC (writeup) :: crypto/HMAC, crypto/CRC, crypto/linear
- supercomputer (code) :: circuits, reverse-engineering
Hack The Vote 2016
- SMTPresident (code) :: crypto/RSA
2013
PHDays CTF 2013 Quals
- bin300 (code) :: crypto/discrete-log
To be completed... See MSLC Blog