40 lines
1.4 KiB
Python
40 lines
1.4 KiB
Python
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from modes.hash_mode import HashMode
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class AvalancheTest:
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"""
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Проверка эффекта лавины:
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небольшое изменение во входном сообщении должно сильно менять хэш.
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"""
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def run(self, variant: str, message: str, salt: str = "", bytes: int = 16) -> dict:
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hasher = HashMode()
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# базовый хэш
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h1 = hasher.run(variant, message, salt=salt, bytes=bytes)
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# изменяем один символ (если пусто — подставим "a")
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if message:
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i = 0 # всегда первый символ для простоты
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flipped_char = chr((ord(message[i]) + 1) % 128)
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mod_msg = flipped_char + message[1:]
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else:
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mod_msg = "a"
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h2 = hasher.run(variant, mod_msg, salt=salt, bytes=bytes)
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# сравнение побитово
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diff_bits = sum(c1 != c2 for c1, c2 in zip(
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bin(int(h1, 16))[2:], bin(int(h2, 16))[2:]))
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total_bits = len(h1) * 4 # HEX -> биты
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return {
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"original": message,
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"modified": mod_msg,
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"hash1": h1,
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"hash2": h2,
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"diff_bits": diff_bits,
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"total_bits": total_bits,
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"diff_percent": round(100 * diff_bits / total_bits, 2),
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}
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