Misc

A bunch of interesting stuff that doesn't fit anywhere else.


One Time Pad

Toggle
  • Gotta Go Fast
    40 pts · 1015 Solves · 23 Solutions

    I won't have have to worry about running out of entropy, I'm going to have my OTP generated forever with this new script!

    Connect at nc socket.cryptohack.org 13372

    Challenge files:
      - 13372.py

    You must be logged in to submit your flag.


  • No Leaks
    100 pts · 756 Solves · 36 Solutions

    Each time you connect, I generate a new one time pad. I also check for leaks, so there's no chance you can learn anything about my secrets!

    Connect at nc socket.cryptohack.org 13370

    Challenge files:
      - 13370.py

    You must be logged in to submit your flag.



PRNGs

Toggle
  • Lo-Hi Card Game
    120 pts · 313 Solves · 6 Solutions

    I'm opening a virtual casino and this is my first game. It's all luck-based and biased towards the house so I'll be a multi-millionaire in no time.

    Connect at nc socket.cryptohack.org 13383

    Challenge files:
      - 13383.py

    You must be logged in to submit your flag.


  • Nothing Up My Sleeve
    150 pts · 188 Solves · 3 Solutions

    My first casino game was a big hit, but there was an issue with the RNG. Some players cheated and others thought it wasn't fair. This time I've picked a better RNG from a cryptographic standard, and I'm mixing in some lucky numbers chosen by the players so that everyone is happy.

    Connect at nc socket.cryptohack.org 13387

    Challenge files:
      - 13387.py

    You must be logged in to submit your flag.


  • Trust Games
    150 pts · 137 Solves · 2 Solutions

    Following the issues with our casino games, we're testing a stronger random number generator. Can you win our trust by finding an attack on our latest model?

    Connect at nc socket.cryptohack.org 13396

    Challenge files:
      - 13396.py


    Challenge contributed by $in

    You must be logged in to submit your flag.



LFSR

Toggle

ElGamal

Toggle

Secret Sharing Schemes

Toggle
  • Armory
    100 pts · 338 Solves · 5 Solutions

    Here's my improvement on Shamir's scheme with deterministically derived shares. Great for storing Bitcoin private keys and other secret data.
    You've only got the first share and you need 3 to unlock the flag so you have no chance.

    Challenge files:
      - armory.py
      - share.txt

    You must be logged in to submit your flag.


  • Toshi's Treasure
    150 pts · 239 Solves · 7 Solutions

    You are hyperreality and you are playing an online treasure hunt with your team mpeg, codecrafting, RichGirlOnLSD and pogo.

    There's one million dollars in a Bitcoin wallet - which nobody yet knows the address for - awaiting the first team to gain 5 of 6 SSSS shares and combine them to a private key. Each member of your team has found one share and you're ready to do the key ceremony to unlock the prize.

    The SSSS implementation is simply the example code on Wikipedia, with the 13th Mersenne prime. The server will tell you your share in the first message.

    You've all agreed to split the million dollars equally, however in a final moment of greed you decide you want it all for yourself!

    Here's your evil plan:

    1. Disrupt the first combination by submitting a fake share. The others assume a mistake was made and try again.

    2. This time, submit a fake share such that the combined secret is a private key for a wallet that you own containing just $1k. This will confuse your teammates and make them think they have been cheated by the game creators, not you.

    3. Unlock the real wallet and use the funds to escape to an island nation where nobody will ever be able to find you.

    Connect at nc socket.cryptohack.org 13384

    Challenge files:
      - hyper_privkey.txt

    You must be logged in to submit your flag.



LWE

Toggle
  • Too Many Errors
    100 pts · 200 Solves · 5 Solutions

    To protect my flag against quantum computers, I've used a quantum-safe Learning With Errors (LWE) distribution on Z_127 to encrypt it. The LWE sample generator is not quite finished though, sometimes it outputs a faulty sample...

    Connect at nc socket.cryptohack.org 13390

    Challenge files:
      - 13390.py


    Challenge contributed by joachim

    You must be logged in to submit your flag.



Password Complexity

Toggle

Level Up

level up icon

You are now level Current level