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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

Ruby Flag Checker

Daily AlpacaHackTopic: RubyReleased: Jan 3, 2026

317 solves
Rev

by

hiikunz

hiikunz

🦙 < I created a flag checker using the Ruby programming language.

Beginner Hint
  • This challenge is in the Rev (Reverse Engineering) category.
  • Flag checkers are a common theme in Rev problems.
  • A flag checker executable or script accepts player input and tells you whether it matches the flag.
  • The provided files are the Ruby source main.rb.
  • The goal is to find an input (the flag) that makes the program print Correct!.
main.rb

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