"""
native/wb_aes.py
=================
Whitebox AES key storage generator.

Instead of storing the AES key as 16 consecutive bytes (trivially
extractable from memory), we scatter the key bytes across a 64-byte
decoy array (_KD) filled with AES Te0 table values:

    aes_key[i] = _KD[_KP[i]] ^ _KM[i]

where _KD is 64 bytes of mixed real-key-bytes + Te0 decoys,
      _KP is the index array (which positions hold key bytes),
      _KM is the XOR mask array (per-byte deobfuscation mask).

This is NOT full whitebox AES (which would require T-tables),
but it prevents trivial key extraction via `strings` or memory scan.
"""
from __future__ import annotations
import random


_SBOX = [
    0x63,0x7c,0x77,0x7b,0xf2,0x6b,0x6f,0xc5,0x30,0x01,0x67,0x2b,0xfe,0xd7,0xab,0x76,
    0xca,0x82,0xc9,0x7d,0xfa,0x59,0x47,0xf0,0xad,0xd4,0xa2,0xaf,0x9c,0xa4,0x72,0xc0,
    0xb7,0xfd,0x93,0x26,0x36,0x3f,0xf7,0xcc,0x34,0xa5,0xe5,0xf1,0x71,0xd8,0x31,0x15,
    0x04,0xc7,0x23,0xc3,0x18,0x96,0x05,0x9a,0x07,0x12,0x80,0xe2,0xeb,0x27,0xb2,0x75,
    0x09,0x83,0x2c,0x1a,0x1b,0x6e,0x5a,0xa0,0x52,0x3b,0xd6,0xb3,0x29,0xe3,0x2f,0x84,
    0x53,0xd1,0x00,0xed,0x20,0xfc,0xb1,0x5b,0x6a,0xcb,0xbe,0x39,0x4a,0x4c,0x58,0xcf,
    0xd0,0xef,0xaa,0xfb,0x43,0x4d,0x33,0x85,0x45,0xf9,0x02,0x7f,0x50,0x3c,0x9f,0xa8,
    0x51,0xa3,0x40,0x8f,0x92,0x9d,0x38,0xf5,0xbc,0xb6,0xda,0x21,0x10,0xff,0xf3,0xd2,
    0xcd,0x0c,0x13,0xec,0x5f,0x97,0x44,0x17,0xc4,0xa7,0x7e,0x3d,0x64,0x5d,0x19,0x73,
    0x60,0x81,0x4f,0xdc,0x22,0x2a,0x90,0x88,0x46,0xee,0xb8,0x14,0xde,0x5e,0x0b,0xdb,
    0xe0,0x32,0x3a,0x0a,0x49,0x06,0x24,0x5c,0xc2,0xd3,0xac,0x62,0x91,0x95,0xe4,0x79,
    0xe7,0xc8,0x37,0x6d,0x8d,0xd5,0x4e,0xa9,0x6c,0x56,0xf4,0xea,0x65,0x7a,0xae,0x08,
    0xba,0x78,0x25,0x2e,0x1c,0xa6,0xb4,0xc6,0xe8,0xdd,0x74,0x1f,0x4b,0xbd,0x8b,0x8a,
    0x70,0x3e,0xb5,0x66,0x48,0x03,0xf6,0x0e,0x61,0x35,0x57,0xb9,0x86,0xc1,0x1d,0x9e,
    0xe1,0xf8,0x98,0x11,0x69,0xd9,0x8e,0x94,0x9b,0x1e,0x87,0xe9,0xce,0x55,0x28,0xdf,
    0x8c,0xa1,0x89,0x0d,0xbf,0xe6,0x42,0x68,0x41,0x99,0x2d,0x0f,0xb0,0x54,0xbb,0x16,
]


def _xtime(x: int) -> int:
    return ((x << 1) ^ (0x1b if x >> 7 else 0)) & 0xFF


def _te0(i: int) -> int:
    s = _SBOX[i]
    return ((_xtime(s)<<24)|(s<<16)|(s<<8)|(_xtime(s)^s)) & 0xFFFFFFFF


def generate(aes_key: bytes, rng: random.Random) -> tuple:
    """
    Returns (kd, kp, km):
        kd : list[int] length 64  — decoy array
        kp : list[int] length 16  — index positions of key bytes in kd
        km : list[int] length 16  — XOR masks per key byte

    Invariant: aes_key[i] == kd[kp[i]] ^ km[i]
    """
    assert len(aes_key) == 16
    positions = rng.sample(range(64), 16)
    masks     = [rng.randint(0, 255) for _ in range(16)]

    # Fill kd with Te0-derived bytes as decoys
    kd = [0] * 64
    for i in range(16):
        v = _te0((i * 4) % 256)
        kd[(i*4)   % 64] = (v >> 24) & 0xFF
        kd[(i*4+1) % 64] = (v >> 16) & 0xFF
        kd[(i*4+2) % 64] = (v >>  8) & 0xFF
        kd[(i*4+3) % 64] = (v      ) & 0xFF

    # Place masked key bytes at chosen positions
    for i, (pos, mask, kb) in enumerate(zip(positions, masks, aes_key)):
        kd[pos] = kb ^ mask

    return kd, positions, masks


def to_c_header(kd: list, kp: list, km: list) -> str:
    """Return C source fragment to inject via -include at build time."""
    def arr(lst, typ="uint8_t"):
        inner = ",".join(f"0x{b:02x}" for b in lst)
        return f"static const {typ} {{name}}[{len(lst)}]={{{inner}}};"
    return (
        "/* Pyrph WB key storage — generated per-build */\n"
        + arr(kd,"uint8_t").replace("{name}","_KD") + "\n"
        + arr(kp,"uint8_t").replace("{name}","_KP") + "\n"
        + arr(km,"uint8_t").replace("{name}","_KM") + "\n"
        + "/* key[i] = _KD[_KP[i]] ^ _KM[i] */\n"
    )


def verify(aes_key: bytes, kd: list, kp: list, km: list) -> bool:
    return all(aes_key[i] == (kd[kp[i]] ^ km[i]) for i in range(16))
