#!/usr/bin/env python3
"""dfpReport 编解码器 — R37 攻坚定论 (2026-08-29)

算法 (R35-R37 三轮活体捕获 + 12/12 历史密文解密验证):
  明文 JSON -> gzip (zlib deflate, gzip wrapper, 头 1f8b08 00 00000000 02 03)
  -> C = RC4(key) keystream XOR gzip (逐字节, 长度保持, 标准 KSA/PRGA 无 drop)
  -> wire body = 密文整段 (前 10B 即所谓 magic 571882cf664bb39401ee = keystream XOR gzip 头,
     不是魔数! 密钥同则 magic 同)
  -> 尾部 10B 为 gzip 流之后的附加段 (decompressobj unused_data)

密钥 = 32 字符 hex ASCII 串 = **APK 内嵌静态常量** (非随机、非设备派生!):
  libhydeviceid.so .data (datadiv 加密) 字符串表 @offset 3912240, 紧邻 "dfpReport"/"appid"/"terminal":
    [3912240] "865a4924a40897ac1fcfe6b4c2abc798"  ← turing appkey/通道密钥 (R39 实锤)
  同族兄弟: k1=...cbb0e3 (BusinessCfg+0x10), channelKey=...cbb045 (resinfo 服务端下发)
  新版本 APK 离线重提取: unidbg hydev harness 跑 datadiv 解密, 或 0x60e6c x1 一次抓取.
XXTEA/静态密钥 f15e... 与 dfpReport 无关 (那是 hdid 子系统) — 45 函数零调用之谜即此.
"""
from __future__ import annotations
import sys, zlib


def rc4_keystream(key: bytes, n: int) -> bytes:
    S = list(range(256))
    j = 0
    for i in range(256):
        j = (j + S[i] + key[i % len(key)]) & 0xFF
        S[i], S[j] = S[j], S[i]
    out = bytearray()
    i = j = 0
    for _ in range(n):
        i = (i + 1) & 0xFF
        j = (j + S[i]) & 0xFF
        S[i], S[j] = S[j], S[i]
        out.append(S[(S[i] + S[j]) & 0xFF])
    return bytes(out)


def decrypt(body: bytes, key: bytes) -> bytes:
    """body = wire body (magic 10B + cipher) -> 指纹 JSON 明文."""
    ks = rc4_keystream(key, len(body))
    plain = bytes(a ^ b for a, b in zip(body, ks))
    d = zlib.decompressobj(31)  # gzip
    json_bytes = d.decompress(plain, 1 << 20)
    return json_bytes


def encrypt(json_bytes: bytes, key: bytes) -> bytes:
    """指纹 JSON -> wire body. 尾部 10B 附加段按全 0 处理 (服务端解 gzip 忽略)."""
    gz = gzip_wrap(json_bytes)
    ks = rc4_keystream(key, len(gz) + 10)
    return bytes(a ^ b for a, b in zip(gz + b"\x00" * 10, ks))


def gzip_wrap(json_bytes: bytes) -> bytes:
    co = zlib.compressobj(9, zlib.DEFLATED, 31)  # gzip wrapper
    gz = co.compress(json_bytes) + co.flush()
    # 对齐 turing 原生 gzip 头: OS 字节 = 0x03 (Unix), Python 写 0x13
    return gz[:9] + b"\x03" + gz[10:]


def _selftest():
    MAGIC = bytes.fromhex("571882cf664bb39401ee")
    KEY = b"865a4924a40897ac1fcfe6b4c2abc798"
    body = open("evidence/dfp_live/dfp_body_4303.bin", "rb").read()
    i = body.find(MAGIC)
    wire = body[i:]
    js = decrypt(wire, KEY)
    assert js.startswith(b'{"Athena"'), js[:40]
    print(f"decrypt OK: {len(js)}B JSON")
    gz = gzip_wrap(js)
    re_enc = encrypt(js, KEY)
    n = len(gz)
    print(f"re-encrypt: gzip {n}B + 10B tail vs wire {len(wire)}B, "
          f"cipher part {'IDENTICAL' if re_enc[:n] == wire[:n] else 'DIFFERS'} "
          f"(magic10 {'==' if re_enc[:10] == wire[:10] else '!='})")


if __name__ == "__main__":
    if len(sys.argv) >= 3 and sys.argv[1] == "dec":
        key = sys.argv[3].encode()
        body = open(sys.argv[2], "rb").read()
        MAGIC = bytes.fromhex("571882cf664bb39401ee")
        i = body.find(MAGIC)
        sys.stdout.buffer.write(decrypt(body[i:], key))
    else:
        _selftest()