52 lines
2.0 KiB
Python
52 lines
2.0 KiB
Python
import os
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from fastapi import FastAPI
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from fastapi.responses import HTMLResponse
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app = FastAPI()
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def generate_substitution_cipher(flag):
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substitution_rules = []
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for i, char in enumerate(flag):
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position = i + 1 # 1-based index
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if char.isalpha():
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if char.isupper():
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substitution_rules.append(f"the {position}th flag is '{char}', upper.\n")
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else: # char is lowercase
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substitution_rules.append(f"the {position}th flag is '{char}', lower.\n")
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else:
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substitution_rules.append(f"the {position}th flag is '{char}', character.\n")
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substitution_dict = {
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'a': 'x', 'b': 'y', 'c': 'z', 'd': 'a', 'e': 'b', 'f': 'c', 'g': 'd',
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'h': 'e', 'i': 'f', 'j': 'g', 'k': 'h', 'l': 'i', 'm': 'j', 'n': 'k',
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'o': 'l', 'p': 'm', 'q': 'n', 'r': 'o', 's': 'p', 't': 'q', 'u': 'r',
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'v': 's', 'w': 't', 'x': 'u', 'y': 'v', 'z': 'w',
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'A': 'X', 'B': 'Y', 'C': 'Z', 'D': 'A', 'E': 'B', 'F': 'C', 'G': 'D',
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'H': 'E', 'I': 'F', 'J': 'G', 'K': 'H', 'L': 'I', 'M': 'J', 'N': 'K',
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'O': 'L', 'P': 'M', 'Q': 'N', 'R': 'O', 'S': 'P', 'T': 'Q', 'U': 'R',
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'V': 'S', 'W': 'T', 'X': 'U', 'Y': 'V', 'Z': 'W',
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' ': ' ' # 保持空格不变
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}
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substitution_rules.append("The quick brown fox jumps a lazy dog.")
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encrypted_rules = []
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for rule in substitution_rules:
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for char in rule:
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if char in substitution_dict:
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encrypted_rules.append(substitution_dict[char])
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else:
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encrypted_rules.append(char)
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return ''.join(encrypted_rules)
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@app.get("/", response_class=HTMLResponse)
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async def read_root():
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flag = os.getenv("GZCTF_FLAG", "Woodpecker{test-Flag_0}")
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cipher_text = generate_substitution_cipher(flag)
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return f"<h1>下面的密文有Flag哦（PS：单表替换）：</h1><p>{cipher_text}</p>"
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if __name__ == "__main__":
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import uvicorn
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uvicorn.run(app, host="0.0.0.0", port=8000)
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