AlpacaHack Logo

Challenges

Sign InSign Up

Rows:

CHALLENGEAUTHORS

SOLVES

(CURRENT)

SOLVE RATE

(AT CONTEST TIME)

AlpacaHack 2100

Daily AlpacaHack

admin

1761

solves

-

1574

solves

-

Daily AlpacaHack

934

solves

-

AlpacaHack Round 2 (Web)

628

solves

Top 28%

= 84/300 users

Daily AlpacaHack

623

solves

-

Daily AlpacaHack

606

solves

-

SECCON Beginners CTF 2024

542

solves

Top 73%

= 683/928 teams

Daily AlpacaHack

409

solves

-

Daily AlpacaHack

406

solves

-

Daily AlpacaHack

375

solves

-

Daily AlpacaHack

367

solves

-

echo

AlpacaHack Round 1 (Pwn)

363

solves

Top 32%

= 56/174 users

Daily AlpacaHack

349

solves

-

Daily AlpacaHack

342

solves

-

Daily AlpacaHack

337

solves

-

Daily AlpacaHack

331

solves

-

Encoding Basics

Daily AlpacaHack

331

solves

-

🐈

Daily AlpacaHack

323

solves

-

Bars

Daily AlpacaHack

318

solves

-

108

Daily AlpacaHack

306

solves

-

Rows:

high and low

Daily AlpacaHackTopic: RNGReleased: Mar 7, 2026

91 solves
Crypto
Hard

by

theoremoon

theoremoon

guess the high or low!

Beginner Hint 1 (AI-translated)
  • server.py implements a custom RNG called RNG.
  • This RNG is a simplified version of Mersenne Twister, making it easier to predict.
  • The goal of this challenge is to predict this custom RNG and increase money until the flag is printed.
Beginner Hint 2 (AI-translated)
  • To predict the RNG, you need to reproduce the server's RNG state on your own machine.
  • The RNG state consists of state and p.
  • p is easy to predict because it is only incremented each time next_value is called.
  • So what about state?
  • Focus on the fact that x can be recovered from y.
server.py
descriptionsolveswriteups