92 lines
2.4 KiB
Python
92 lines
2.4 KiB
Python
"""虎牙 udb 登录证书 (biz_token) 铸造与解析工具。
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证书格式：base64( [0x0c][key_idx][AES-128-ECB(key16, zeropad(P1))] )
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"""
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from __future__ import annotations
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import base64
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import os
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import struct
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from .udb_aes import udb_decrypt, udb_encrypt
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KEY_TABLE_RAW = [
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"4VYcPdvKKqjBHZtCmbroRXHk",
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"xXEDWqiKLGwEZ6HubEiswCqK",
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"3FMHubdKosFrhmXNLHTNHZwe",
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]
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DEFAULT_KEY16 = KEY_TABLE_RAW[0][:16].encode()
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def build_p1(
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app_id: bytes,
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fingerprint: bytes,
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cred: bytes,
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rnd: bytes | None = None,
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) -> bytes:
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"""按样本结构组装 P1 明文。
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- app_id: b'5008' 等 4 字节
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- fingerprint: 40 字节 ASCII hex
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- cred: 114 字节 hyCred
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- rnd: 20 字节 nonce，缺省用 os.urandom(20)
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"""
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assert len(fingerprint) == 40, f"指纹应为40B, 实际为 {len(fingerprint)}"
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assert len(cred) == 114, f"cred应为114B, 实际为 {len(cred)}"
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r = os.urandom(20) if rnd is None else rnd
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p1 = b"\x01\x04\x00" + app_id
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p1 += struct.pack("<H", len(r)) + r
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p1 += struct.pack("<H", len(fingerprint)) + fingerprint
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p1 += struct.pack("<H", len(cred)) + cred
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assert len(p1) == 187, f"P1长度应为187，实际为 {len(p1)}"
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return p1
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def parse_p1(data: bytes) -> dict:
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"""解析 P1 结构。"""
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o = 0
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def tk(n: int) -> bytes:
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nonlocal o
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b = data[o : o + n]
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o += n
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return b
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out = {
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"head": tk(3).hex(),
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"app_id": tk(4),
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}
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n = struct.unpack("<H", tk(2))[0]
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out["rnd"] = tk(n)
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n = struct.unpack("<H", tk(2))[0]
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out["fingerprint"] = tk(n)
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n = struct.unpack("<H", tk(2))[0]
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out["cred"] = tk(n)
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out["trailing"] = data[o:]
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return out
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def forge_cert(
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p1: bytes,
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key16: bytes = DEFAULT_KEY16,
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key_idx: int = 0x20,
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type_byte: int = 0x0C,
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) -> bytes:
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"""P1 -> 二进制证书 [type][key_idx][192B AES 密文]。"""
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ct = udb_encrypt(key16, p1)
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assert len(ct) == 192, len(ct)
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return bytes([type_byte, key_idx]) + ct
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def parse_cert(blob: bytes) -> tuple[int, int, bytes]:
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"""[0x0c][idx][192B] -> (type, idx, ct)。"""
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assert blob[0] == 0x0C and len(blob) >= 194, "非证书结构"
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return blob[0], blob[1], blob[2:194]
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def decrypt_cert(blob: bytes, key16: bytes = DEFAULT_KEY16) -> bytes:
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"""解密二进制证书为 P1 明文。"""
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_, _, ct = parse_cert(blob)
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return udb_decrypt(key16, ct)
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