90 lines
2.4 KiB
Python
90 lines
2.4 KiB
Python
"""虎牙证书 nonce(rnd) 本地生成器。
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基于 XXTEA 算法与 uid + k1 派生密钥。
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"""
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from __future__ import annotations
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import hashlib
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import struct
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import time
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K1_DEFAULT = "865a4924a40897ac1fcfe6b4c2cbb0e3"
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def _xxtea_encrypt_words(v: list[int], k: list[int]) -> list[int]:
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"""标准 XXTEA (delta=0x9e3779b9, rounds=6+52/n)。"""
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n = len(v)
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if n < 2:
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return v
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z = v[n - 1]
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y = v[0]
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s = 0
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delta = 0x9E3779B9
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q = 6 + 52 // n
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while q > 0:
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s = (s + delta) & 0xFFFFFFFF
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e = (s >> 2) & 3
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p = 0
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while p < n - 1:
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y = v[p + 1]
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z = (
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v[p]
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+ (
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(((z >> 5) ^ (y << 2)) + ((y >> 3) ^ (z << 4)))
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^ ((s ^ y) + (k[(p & 3) ^ e] ^ z))
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)
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) & 0xFFFFFFFF
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v[p] = z
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p += 1
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y = v[0]
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z = (
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v[n - 1]
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+ (
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(((z >> 5) ^ (y << 2)) + ((y >> 3) ^ (z << 4)))
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^ ((s ^ y) + (k[((n - 1) & 3) ^ e] ^ z))
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)
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) & 0xFFFFFFFF
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v[n - 1] = z
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q -= 1
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return v
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def xxtea_encrypt(data: bytes, key16: bytes) -> bytes:
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"""虎牙专用 XXTEA: 输出 words = ceil(len/4)+1, 末尾 word 存原始长度。"""
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n = len(data)
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nwords = (n // 4) + 1
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v = [0] * nwords
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for i in range(n // 4):
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v[i] = struct.unpack("<I", data[i * 4 : i * 4 + 4])[0]
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v[nwords - 1] = n
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k = [struct.unpack("<I", key16[i * 4 : i * 4 + 4])[0] for i in range(4)]
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_xxtea_encrypt_words(v, k)
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return b"".join(struct.pack("<I", w & 0xFFFFFFFF) for w in v)
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def pack_u64(v: int) -> bytes:
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"""8字节小端裸值。"""
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return struct.pack("<Q", v & 0xFFFFFFFFFFFFFFFF)
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def gen_nonce(
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uid: int,
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k1: str = K1_DEFAULT,
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service_time_ms: int | None = None,
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counter: int = 0,
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) -> bytes:
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"""按设备算法生成 20B nonce(rnd)。
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- uid: 虎牙 uid 数字（如 1199666914671）
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- k1: 设备常量 32hex
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- service_time_ms: 缺省为当前毫秒时间戳
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- counter: 计数器（通常为 0）
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"""
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st = service_time_ms if service_time_ms is not None else int(time.time() * 1000)
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st &= 0x7FFFFFFFFFFF
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nonce_val = (counter & 0xFFFF) | (st << 16)
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data = pack_u64(st) + pack_u64(nonce_val)
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key = hashlib.md5((str(uid) + k1).encode()).hexdigest()[:16].encode()
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return xxtea_encrypt(data, key)
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