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Tag: Flag Checker

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Flag Checker

Flag checkers are a common type of challenge in the Reverse Engineering category.

An executable or script called a flag checker takes the player's input and outputs whether that input matches the flag.

These challenges may also be called "crackmes" in a broader sense. (automatically translated from Japanese)

minaminao
·Updated May 3, 2026
Flag Checker Challenges

Sugoi Flag Checker

Daily AlpacaHackTopic: ELFReleased: Dec 12, 2025

224 solves
Rev

by

chocorusk

chocorusk

A super flag checker that uses a super cryptographic algorithm.

Beginner Hint 1 (AI-translated)
  • chal is an ELF executable. First, try decompiling it with a reverse engineering tool such as IDA Free, Ghidra, or Binary Ninja.
  • Also, this challenge is Hard, so if you are a beginner, we recommend using AI as needed.
  • For example, you can drag and drop the binary into ChatGPT and ask it to help with the analysis.
Beginner Hint 2: Spoiler Alert! (AI-translated)
  • Actually, you can solve this challenge without understanding most of the cryptographic processing.
  • Focus on what strings are being compared by the strcmp function.
chal

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