Overview 2022

An overview of all CTF challenges I checked out this year. Some even contain a write-up I wrote, although they can be quite sparse. Feel free to contact me about any of the challenges below. ^w^

Check out write-ups by my teammates on K3RN3L4RMY.com

HackPack CTF 2022


The challenges I wrote:

  • Repeating Offense - Crypto 443 pts (20 solves) › Homomorphism attack on layered RSA + Paillier scheme(s)
  • P(ai)^3 - Crypto 469 pts (15 solves) › Faulty Paillier scheme leaks primes and message

UMassCTF 2022


The challenges I wrote:

  • HatMash - Crypto 500 pts (1 solve) › Hashing algorithm based on linear algebra

LINE CTF 2022


  • ss-puzzle - Crypto 100 pts (221 solves) › Simple XOR puzzle
  • X Factor - Crypto 100 pts (102 solves) › Homomorphically combined unpadded RSA signatures to forge a signature
  • Baby crypto revisited - Crypto 138 pts (48 solves) › ECDSA hidden number problem solved with lattice magic
  • Forward-or - Crypto 145 pts (43 solves) › Present cipher meet-in-the-middle attack
  • lazy-STEK - Crypto 290 pts (9 solves) ›

zer0pts CTF 2022


  • Anti-Fermat - Crypto 90 pts (125 solves) › RSA with related primes allows for factorisation of public modulus
  • CurveCrypto - Crypto 156 pts (36 solves) › EC encryption scheme susceptible to Coppersmith’s short-pad attack
  • EDDH - Crypto 188 pts (24 solves) › Invalid curve attack on key exchange over Edwards curve
  • OK - Crypto 289 pts (9 solves) ›
  • Karen - Crypto 304 pts (8 solves) ›

UTCTF 2022


  • Scrambled - Crypto 937 pts (54 solves) › Substitution cipher broken by frequency analysis
  • Failed Hash Function - Crypto 974 pts (35 solves) › Keyed hash function leaks key bits through i/o analysis
  • Sunset - Crypto 996 pts (15 solves) › Alternative diffie-hellman key exchange broken through simple linear algebra

DaVinciCTF 2022


  • RSA - Crypto 87 pts (79 solves) › Factorisation of public modulus using leaked totient
  • small weiner - Crypto 355 pts (72 solves) › RSA Weiner attack to recover small private exponent
  • Secure Or Not Secure - Crypto 383 pts (65 solves) › Re-used key stream into cookie forgery
  • Cwyptographic Owacle - Crypto 467 pts (35 solves) › ECDSA with predictable nonce generation leaks private key

DefCamp CTF 21-22 Online


  • algorithm - Crypto 50 pts (94 solves) › Polynomial RSA still does not work
  • raw-image - Crypto 179 pts (46 solves) › Image XOR
  • malwy - Rev 200 pts (43 solves) ›
  • rsa-factory - Crypto 450 pts (8 solves) ›
  • P2DPI - Crypto 450 pts (8 solves) ›

ATR HAX by Trellix


  • Modnar - Crypto 300 pts (? solves) › Time-seeded PRNG

DiceCTF 2022


  • baby-rsa - Crypto 117 pts (162 solves) › (p-1)(q-1) divisible by e**2
  • rejected - Crypto 117 pts (162 solves) › Simulated timing leaks internal state bits
  • correlated - Crypto 117 pts (162 solves) › Noisy LFSR output recovered by fast correlation attack, or by luck :)
  • commitment-issues - Crypto 117 pts (162 solves) ›
  • pow-pow - Crypto 117 pts (162 solves) ›
  • learning without errors - Crypto 117 pts (162 solves) ›
  • shibari - Crypto 117 pts (162 solves) ›
  • psych - Crypto 117 pts (162 solves) ›

Real World CTF 4th


  • Treasure Hunter - Crypto ? pts (? solves) › Smart contract with sparse Merkle tree verification

TetCTF 2022


  • shares - Crypto 216 pts (29 solves) ›
  • shares_v2 - Crypto 804 pts (15 solves) ›
  • algebra - Crypto 831 pts (14 solves) ›
  • fault - Crypto 831 pts (14 solves) ›