Port PSN pkg decryption to pure Python (drop Wine requirement)
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"""Pure-Python PSP/PSX PSN ``.pkg`` decryption (no Wine / pkg2zip needed).
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Ports the folder-mode extraction used by pkgi-psp's depackager and pkg2zip:
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parse the ``\\x7FPKG`` header, derive the PSP AES key, AES-CTR-decrypt the file
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entries, and write the game's ``EBOOT.PBP`` (+ siblings) into a folder. The
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resulting ``EBOOT.PBP`` keeps its DATA.PSP EDAT-encrypted, so it runs on CFW
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with the ``npdrm_free`` plugin (ARK ships it) — same as pkgi-psp's install.
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"""
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from __future__ import annotations
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from pathlib import Path
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PKG_MAGIC = 0x7F504B47
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# Static PSN keys (key type 1 = PSP).
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PSP_KEY = bytes.fromhex("07f2c68290b50d2c33818d709b60e62b")
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PS3_KEY = bytes.fromhex("2e7b71d7c9c9a14ea3221f188828b8f8")
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try:
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from Crypto.Cipher import AES as _AES # pycryptodome (fast)
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_HAVE_CRYPTO = True
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except ImportError: # noqa: BLE001
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_HAVE_CRYPTO = False
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# --------------------------------------------------------------------------- #
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# Pure-Python AES-128 (fallback when pycryptodome is unavailable)
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# --------------------------------------------------------------------------- #
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_SBOX = bytes.fromhex(
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"637c777bf26b6fc53001672bfed7ab76ca82c97dfa5947f0add4a2af9ca472c0"
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"b7fd9326363ff7cc34a5e5f171d8311504c723c31896059a071280e2eb27b275"
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"09832c1a1b6e5aa0523bd6b329e32f8453d100ed20fcb15b6acbbe394a4c58cf"
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"d0efaafb434d338545f9027f503c9fa851a3408f929d38f5bcb6da2110fff3d2"
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"cd0c13ec5f974417c4a77e3d645d197360814fdc222a908846eeb814de5e0bdb"
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"e0323a0a4906245cc2d3ac629195e479e7c8376d8dd54ea96c56f4ea657aae08"
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"ba78252e1ca6b4c6e8dd741f4bbd8b8a703eb5664803f60e613557b986c11d9e"
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"e1f8981169d98e949b1e87e9ce5528df8ca1890dbfe6426841992d0fb054bb16"
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)
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_RCON = (0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1B, 0x36)
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def _key_schedule(key):
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w = list(key)
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for i in range(4, 44):
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t = list(w[(i - 1) * 4:(i - 1) * 4 + 4])
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if i % 4 == 0:
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t = t[1:] + t[:1]
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t = [_SBOX[b] for b in t]
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t[0] ^= _RCON[i // 4 - 1]
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w += [w[(i - 4) * 4 + j] ^ t[j] for j in range(4)]
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return [bytes(w[i * 16:(i + 1) * 16]) for i in range(11)]
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def _shift_rows(s):
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return [s[0], s[5], s[10], s[15], s[4], s[9], s[14], s[3],
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s[8], s[13], s[2], s[7], s[12], s[1], s[6], s[11]]
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def _xtime(a):
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a <<= 1
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return (a ^ 0x1B) & 0xFF if a & 0x100 else a & 0xFF
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def _mix_columns(s):
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out = [0] * 16
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for c in range(4):
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a0, a1, a2, a3 = s[4 * c], s[4 * c + 1], s[4 * c + 2], s[4 * c + 3]
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out[4 * c] = _xtime(a0) ^ (_xtime(a1) ^ a1) ^ a2 ^ a3
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out[4 * c + 1] = a0 ^ _xtime(a1) ^ (_xtime(a2) ^ a2) ^ a3
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out[4 * c + 2] = a0 ^ a1 ^ _xtime(a2) ^ (_xtime(a3) ^ a3)
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out[4 * c + 3] = (_xtime(a0) ^ a0) ^ a1 ^ a2 ^ _xtime(a3)
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return out
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def _aes_encrypt_block(rk, block):
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s = [block[i] ^ rk[0][i] for i in range(16)]
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for rnd in range(1, 10):
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s = [_SBOX[b] for b in s]
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s = _shift_rows(s)
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s = _mix_columns(s)
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s = [s[i] ^ rk[rnd][i] for i in range(16)]
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s = [_SBOX[b] for b in s]
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s = _shift_rows(s)
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s = [s[i] ^ rk[10][i] for i in range(16)]
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return bytes(s)
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def _add128(counter, n):
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c = bytearray(counter)
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for i in range(15, -1, -1):
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n += c[i]
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c[i] = n & 0xFF
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n >>= 8
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return bytes(c)
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def _ctr_decrypt_py(key, iv, block_index, data):
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"""AES-CTR decrypt (pure-Python): counter = iv + block_index, +1 per block."""
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rk = _key_schedule(key)
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counter = _add128(iv, block_index)
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out = bytearray()
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for i in range(0, len(data), 16):
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ks = _aes_encrypt_block(rk, counter)
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out += bytes(b ^ k for b, k in zip(data[i:i + 16], ks))
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counter = _add128(counter, 1)
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return bytes(out)
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def _ctr_decrypt(key, iv, block_index, data):
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"""AES-CTR decrypt: 128-bit big-endian counter at ``iv + block_index``."""
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if _HAVE_CRYPTO:
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nonce = iv[:8]
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init = int.from_bytes(iv[8:16], "big") + block_index
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return _AES.new(key, _AES.MODE_CTR, nonce=nonce, initial_value=init).decrypt(data)
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return _ctr_decrypt_py(key, iv, block_index, data)
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def _make_ctr_decryptor(key, iv, block_index):
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"""Return a streaming decryptor (callable: bytes -> bytes) for a data run."""
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if _HAVE_CRYPTO:
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nonce = iv[:8]
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init = int.from_bytes(iv[8:16], "big") + block_index
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cipher = _AES.new(key, _AES.MODE_CTR, nonce=nonce, initial_value=init)
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return cipher.decrypt
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rk = _key_schedule(key)
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counter = _add128(iv, block_index)
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state = {"rk": rk, "counter": counter}
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def decrypt(chunk):
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out = bytearray()
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for i in range(0, len(chunk), 16):
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ks = _aes_encrypt_block(state["rk"], state["counter"])
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out += bytes(b ^ k for b, k in zip(chunk[i:i + 16], ks))
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state["counter"] = _add128(state["counter"], 1)
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return bytes(out)
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return decrypt
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# --------------------------------------------------------------------------- #
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# PKG extraction
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# --------------------------------------------------------------------------- #
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def extract(pkg_path, dest_dir, progress_cb=None, cancel_event=None):
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"""Decrypt a PSP/PSX PSN pkg into ``dest_dir/<TITLE_ID>/``.
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Returns ``(kind, title_id, folder)`` where kind is ``"psp"`` or ``"psx"``.
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"""
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from .store import TransferCancelled
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pkg_path = Path(pkg_path)
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dest_dir = Path(dest_dir)
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with open(pkg_path, "rb") as fh:
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header = fh.read(0x100)
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if len(header) < 0xE8 or int.from_bytes(header[0:4], "big") != PKG_MAGIC:
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raise RuntimeError(f"not a PKG file: {pkg_path.name}")
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meta_offset = int.from_bytes(header[8:12], "big")
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meta_count = int.from_bytes(header[12:16], "big")
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item_count = int.from_bytes(header[20:24], "big")
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enc_offset = int.from_bytes(header[32:40], "big")
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iv = header[0x70:0x80]
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key_type = header[0xE7] & 7
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title_id = header[0x37:0x40].decode("ascii", "replace").rstrip("\x00").strip() or "PKG"
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content_type = 0
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items_offset = 0
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with open(pkg_path, "rb") as fh:
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off = meta_offset
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for _ in range(meta_count):
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fh.seek(off)
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m = fh.read(16)
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if len(m) < 16:
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break
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mtype = int.from_bytes(m[0:4], "big")
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msize = int.from_bytes(m[4:8], "big")
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if mtype == 2:
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content_type = int.from_bytes(m[8:12], "big")
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elif mtype == 13:
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items_offset = int.from_bytes(m[8:12], "big")
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off += 8 + msize
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if content_type == 6:
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kind = "psx"
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elif content_type in (7, 0xE, 0xF, 0x10):
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kind = "psp"
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else:
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raise RuntimeError(f"unsupported NoPayStation content type 0x{content_type:x}")
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if key_type != 1:
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raise RuntimeError(f"unsupported PKG key type {key_type}")
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main_key = PSP_KEY
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ps3_key = PS3_KEY
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# Decrypt the whole item table in one shot.
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with open(pkg_path, "rb") as fh:
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fh.seek(enc_offset + items_offset)
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table = fh.read(item_count * 32)
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table = _ctr_decrypt(main_key, iv, items_offset // 16, table)
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entries = []
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for i in range(item_count):
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e = table[i * 32:(i + 1) * 32]
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name_offset = int.from_bytes(e[0:4], "big")
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name_size = int.from_bytes(e[4:8], "big")
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data_offset = int.from_bytes(e[8:16], "big")
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data_size = int.from_bytes(e[16:24], "big")
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psp_type = e[24]
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flags = e[27]
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if flags in (4, 18) or data_size == 0:
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continue
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item_key = main_key if psp_type == 0x90 else ps3_key
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entries.append((name_offset, name_size, data_offset, data_size, item_key))
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folder = dest_dir / title_id
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folder.mkdir(parents=True, exist_ok=True)
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written = []
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total = sum(ds for *_, ds, _ in entries) or 1
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done = 0
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with open(pkg_path, "rb") as fh:
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for name_offset, name_size, data_offset, data_size, item_key in entries:
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if cancel_event is not None and cancel_event.is_set():
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raise TransferCancelled()
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fh.seek(enc_offset + name_offset)
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name = _ctr_decrypt(item_key, iv, name_offset // 16, fh.read(name_size))
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name = name.split(b"\x00", 1)[0].decode("utf-8", "replace")
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base = name.rsplit("/", 1)[-1]
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if kind == "psx" and base not in ("EBOOT.PBP", "DOCUMENT.DAT"):
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continue
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if kind == "psp" and base not in ("EBOOT.PBP", "PSP-KEY.EDAT", "CONTENT.DAT"):
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continue
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dest = folder / base
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decrypt = _make_ctr_decryptor(item_key, iv, data_offset // 16)
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fh.seek(enc_offset + data_offset)
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with open(dest, "wb") as out:
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remaining = data_size
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while remaining > 0:
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if cancel_event is not None and cancel_event.is_set():
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raise TransferCancelled()
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chunk = fh.read(min(1 << 20, remaining))
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if not chunk:
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break
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out.write(decrypt(chunk))
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remaining -= len(chunk)
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done += len(chunk)
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if progress_cb is not None:
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progress_cb("Extracting", min(done / total, 1.0), "")
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written.append(dest)
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if not (folder / "EBOOT.PBP").exists():
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raise RuntimeError(f"no EBOOT.PBP found in {pkg_path.name}")
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return kind, title_id, folder
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