#!/usr/bin/env python3
"""虎牙 udb 登录证书(biz_token)解析/铸造工具 —— 算法已完全闭环(2026-08-25)。

== 已证实的完整算法链 ==

证书 = base64( [0x0c][key_idx][AES-128-ECB(key16, zeropad(P1))] )

  P1 (187B) 结构（两份活体样本逐字段对齐验证）:
    [0x01][0x04][0x00]        固定头
    ["5008"]                  appId
    [u16_le=20][20B 随机数]    每次生成时随机
    [u16_le=40][40B 指纹hex]   设备指纹ASCII("02df39879743..."), 设备绑定、跨会话不变
    [u16_le=114][114B cred]   hyCred 二进制 (=udb_cred base64解码)

  key16 来源: AESkeyMgr 密钥表。rodata 内置默认三条(0x1bc810, 注册id=3/4/5):
      4VYcPdvKKqjBHZtCmbroRXHk   <- 本次活体实测在用(取前16字节)
      xXEDWqiKLGwEZ6HubEiswCqK
      3FMHubdKosFrhmXNLHTNHZwe
  服务端可下发会话密钥(NEWKEY/key_id机制), 证书第二字节即 key_idx:
      今日 getQUrlData 样本 idx=0x20 <-> "4VYcPdvKKqjBHZtC";
      更早样本 idx=0x50 用默认钥解不开 => 属服务端下发钥。
  UdbAESUtil 本体为标准 AES-128-ECB(FIPS-197 KAT 逐位一致), 无魔改。

调用链: HandlerGetH5InfoEx::onHandler -> BusinessCfg::getOtp -> ... ->
  gen_biz_token(BIZTOKEN,P1部件...,out) @0x3307e4
  -> enpack_header/enpack_body/cred_packls/xxtea_encrypt
  -> encode_aes(P1, key24, out) @0x330218   # C1 只读 key 前16字节
  -> UdbAESUtil::encrypt @0x250038          # 补零到16倍数逐块
  -> CBase64::Encode

验证脚本: scripts/hook_aes_diff.py(差分) / scripts/hook_cert_keycap.py(抓钥)
证据: evidence/aes_diff.json / evidence/cert_keycap.json
"""
from __future__ import annotations

import base64
import os
import struct
import sys
from pathlib import Path

sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
from tools.udb_aes import udb_decrypt, udb_encrypt  # noqa: E402

# so rodata 0x1bc810 起连排的三条24字符默认密钥(AESkeyMgr 注册 id=3/4/5)
KEY_TABLE_RAW = [
    "4VYcPdvKKqjBHZtCmbroRXHk",
    "xXEDWqiKLGwEZ6HubEiswCqK",
    "3FMHubdKosFrhmXNLHTNHZwe",
]
DEFAULT_KEY16 = KEY_TABLE_RAW[0][:16].encode()  # 本次活体验证在用


# ---------------------------------------------------------------- P1 组装/解析
def build_p1(app_id: bytes, fingerprint: bytes, cred: bytes,
             rnd: bytes | None = None) -> bytes:
    """按活体样本结构组装 P1 明文。

    fingerprint: 40字节 ASCII hex 形如 b'02df39879743...'（设备绑定）
    cred:        114 字节 hyCred 二进制（base64(udb_cred) 解码后）
    rnd:         缺省用 os.urandom(20)
    """
    assert len(fingerprint) == 40, f"指纹应40B, 得到{len(fingerprint)}"
    assert len(cred) == 114, f"cred应114B, 得到{len(cred)}"
    r = os.urandom(20) if rnd is None else rnd
    p1 = b"\x01\x04\x00" + app_id
    p1 += struct.pack("<H", len(r)) + r
    p1 += struct.pack("<H", len(fingerprint)) + fingerprint
    p1 += struct.pack("<H", len(cred)) + cred
    assert len(p1) == 187, len(p1)
    return p1


def parse_p1(data: bytes) -> dict:
    o = 0

    def tk(n: int) -> bytes:
        nonlocal o
        b = data[o:o + n]
        o += n
        return b

    out = {
        "head": tk(3).hex(),
        "app_id": tk(4),
    }
    n = struct.unpack("<H", tk(2))[0]
    out["rnd"] = tk(n)
    n = struct.unpack("<H", tk(2))[0]
    out["fingerprint"] = tk(n)
    n = struct.unpack("<H", tk(2))[0]
    out["cred"] = tk(n)
    out["trailing"] = data[o:]
    return out


# ---------------------------------------------------------------- 证书层
def forge_cert(p1: bytes, key16: bytes = DEFAULT_KEY16,
               key_idx: int = 0x20, type_byte: int = 0x0C) -> bytes:
    """P1 -> 二进制证书 [type][key_idx][192B AES 密文]。"""
    ct = udb_encrypt(key16, p1)
    assert len(ct) == 192, len(ct)
    return bytes([type_byte, key_idx]) + ct


def cert_b64(cert: bytes) -> str:
    return base64.b64encode(cert).decode()


def parse_cert(blob: bytes) -> tuple[int, int, bytes]:
    """[0x0c][idx][192B] -> (type, idx, ct)。"""
    assert blob[0] == 0x0C and len(blob) >= 194, "非证书结构"
    return blob[0], blob[1], blob[2:194]


def decrypt_cert(blob: bytes, key16: bytes = DEFAULT_KEY16) -> bytes:
    _, _, ct = parse_cert(blob)
    return udb_decrypt(key16, ct)


# ---------------------------------------------------------------- 兼容旧接口
def try_decrypt_all(ct192: bytes) -> list[tuple[str, bytes]]:
    return [(k[:16], udb_decrypt(k[:16].encode(), ct192)) for k in KEY_TABLE_RAW]


if __name__ == "__main__":
    import json
    ev = json.load(open(Path(__file__).resolve().parent.parent /
                        "evidence/cert_keycap.json"))
    enc_in = next(e for e in ev if e.get("type") == "enc_in")
    P1 = bytes.fromhex(enc_in["x1s"]["v"])
    fields = parse_p1(P1)
    print("P1 解析:", {k: (v.hex()[:32] if isinstance(v, bytes) else v)
                      for k, v in fields.items()})
    # 用捕获的 P1 重铸并与活体密文比对
    qurl = next(e["data"] for e in ev if e.get("type") == "qurl_done" and e.get("data"))
    import re
    raw = base64.b64decode(qurl)
    inner = []
    for x in re.findall(rb"[A-Za-z0-9+/]{100,}={0,2}", raw):
        try:
            inner.append(base64.b64decode(x + b"=" * ((-len(x)) % 4)))
        except Exception:
            pass
    blob = max(inner, key=len)
    mine = forge_cert(P1)
    print("活体证书 :", blob.hex()[:64])
    print("重铸证书 :", mine.hex()[:64])
    print("FULL MATCH:", mine == blob)