Sugoi Flag Checker

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Rows:

CHALLENGE	AUTHORS	SOLVES (CURRENT)	SOLVE RATE (AT CONTEST TIME)
Welcome Misc	admin	1428 solves	-
AlpacaHack 2100 Misc Daily AlpacaHack	admin	1250 solves	-
a fact of CTF Crypto Daily AlpacaHack	xornet	737 solves	-
Simple Login Web AlpacaHack Round 2 (Web)	ark	570 solves	Top 28% = 84/300 users
Emojify Web Daily AlpacaHack	ark	499 solves	-
Leaked Flag Checker Rev Daily AlpacaHack	minaminao	480 solves	-
simpleoverflow Pwn Daily AlpacaHack	n01e0	426 solves	-
echo Pwn AlpacaHack Round 1 (Pwn)	ptr-yudai	339 solves	Top 32% = 56/174 users
super-tomato Crypto Daily AlpacaHack	kanon	325 solves	-
hit-and-miss Misc Daily AlpacaHack	ark	314 solves	-
Alpaca Bank Web Daily AlpacaHack	hiikunz	288 solves	-
Xmas Login Web Daily AlpacaHack	hiikunz	287 solves	-
Integer Writer Pwn Daily AlpacaHack	mora	283 solves	-
Fushigi Crawler Web Daily AlpacaHack	minaminao	282 solves	-
Read Assembly Rev Daily AlpacaHack	xrekkusu	278 solves	-
size limit Crypto Daily AlpacaHack	jp3bgy	277 solves	-
Encoding Basics Misc Crypto Daily AlpacaHack	kurenaif	272 solves	-
🐈 Web Daily AlpacaHack	ark	270 solves	-
Treasure Hunt Web AlpacaHack Round 7 (Web)	ark	265 solves	Top 15% = 71/458 users
108 Misc Daily AlpacaHack	admin	252 solves	-

Rows:

186 solves

Author:

chocorusk

A super flag checker that uses a super cryptographic algorithm.

Beginner Hint①

chal は ELF 実行ファイルです。まずは、IDA Free, Ghidra, Binary Ninja などのリバースエンジニアリングツールでデコンパイルしてみましょう。
また、この問題の難易度は Hard なので、初心者の方は適宜 AI を活用することをおすすめします。
例えば、 ChatGPT にはバイナリをドラッグ・アンド・ドロップで添付でき、解析を手伝ってくれます。

Beginner Hint② (ネタバレ注意！)