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from __future__ import annotations

import ast

import random

from collections.abc import Sequence

class StringEncryptor(ast.NodeTransformer):

def __init__(self, rng: random.Random, decrypt_str_name: str, decrypt_bytes_name: str, pool_name: str):

self.rng = rng

self.dec_s = decrypt_str_name

self.dec_b = decrypt_bytes_name

self.pool_name = pool_name

self.entries: list[tuple[list[bytes], list[bytes], list[int], list[int], int, int]] = []

def _strip_docstring(self, body: list[ast.stmt]) -> list[ast.stmt]:

if body and isinstance(body[0], ast.Expr) and isinstance(body[0].value, ast.Constant) and isinstance(body[0].value.value, str):

return body[1:] or [ast.Pass()]

return body

def visit_Module(self, node: ast.Module) -> ast.AST:

node.body = self._strip_docstring(node.body)

self.generic_visit(node)

return node

def visit_FunctionDef(self, node: ast.FunctionDef) -> ast.AST:

node.body = self._strip_docstring(node.body)

self.generic_visit(node)

return node

visit_AsyncFunctionDef = visit_FunctionDef

def visit_ClassDef(self, node: ast.ClassDef) -> ast.AST:

node.body = self._strip_docstring(node.body)

self.generic_visit(node)

return node

def visit_JoinedStr(self, node: ast.JoinedStr) -> ast.AST:

new_values: list[ast.AST] = []

for v in node.values:

if isinstance(v, ast.FormattedValue):

v.value = self.visit(v.value)

if v.format_spec is not None:

v.format_spec = self.visit(v.format_spec)

new_values.append(v)

else:

new_values.append(v)

node.values = new_values

return node

def visit_match_case(self, node: ast.match_case) -> ast.AST:

if node.guard is not None:

node.guard = self.visit(node.guard)

node.body = [self.visit(stmt) for stmt in node.body]

return node

def visit_Constant(self, node: ast.Constant) -> ast.AST:

v = node.value

if isinstance(v, bool):

return node

if isinstance(v, str):

return self._encrypt_str(v) if v else node

if isinstance(v, bytes):

return self._encrypt_bytes(v) if v else node

return node

def _make_key(self, n_min: int=4, n_max: int=24) -> bytes:

return bytes((self.rng.randrange(256) for _ in range(self.rng.randint(n_min, n_max))))

def _xor(self, data: bytes, key: bytes) -> bytes:

return bytes((b ^ key[i % len(key)] for i, b in enumerate(data)))

def _rotate_left(self, data: bytes, amount: int) -> bytes:

if not data:

return data

amount %= len(data)

return data[amount:] + data[:amount]

def _split_chunks(self, data: bytes) -> list[bytes]:

if len(data) <= 2:

return [data]

max_chunks = min(8, len(data))

min_chunks = 2 if len(data) > 4 else 1

count = self.rng.randint(min_chunks, max_chunks)

if count <= 1:

return [data]

cuts = sorted(self.rng.sample(range(1, len(data)), count - 1))

positions = [0, *cuts, len(data)]

return [data[positions[i]:positions[i + 1]] for i in range(len(positions) - 1)]

def _shuffle_chunks(self, chunks: Sequence[bytes]) -> tuple[list[bytes], list[int]]:

if len(chunks) <= 1:

return list(chunks), [0]

shuffled_indexes = list(range(len(chunks)))

self.rng.shuffle(shuffled_indexes)

shuffled = [chunks[i] for i in shuffled_indexes]

order = [shuffled_indexes.index(i) for i in range(len(chunks))]

return shuffled, order

def _bytes_tuple(self, values: Sequence[bytes]) -> ast.Tuple:

return ast.Tuple(elts=[ast.Constant(value=value) for value in values], ctx=ast.Load())

def _int_tuple(self, values: Sequence[int]) -> ast.Tuple:

return ast.Tuple(elts=[ast.Constant(value=value) for value in values], ctx=ast.Load())

def _encoded_entry(self, data: bytes, key: bytes) -> tuple[list[bytes], list[bytes], list[int], list[int], int, int]:

enc = self._xor(data, key)

rotation = self.rng.randrange(len(enc)) if enc else 0

rotated = self._rotate_left(enc, rotation)

data_chunks, data_order = self._shuffle_chunks(self._split_chunks(rotated))

key_chunks, key_order = self._shuffle_chunks(self._split_chunks(key))

mode = self.rng.randrange(3)

return data_chunks, key_chunks, data_order, key_order, rotation, mode

def _store_entry(self, data: bytes, key: bytes) -> int:

idx = len(self.entries)

self.entries.append(self._encoded_entry(data, key))

return idx

def _pool_ref(self, idx: int, decoder_name: str) -> ast.Call:

return ast.Call(

func=ast.Name(id=decoder_name, ctx=ast.Load()),

args=[

ast.Name(id=self.pool_name, ctx=ast.Load()),

ast.Constant(value=idx),

],

keywords=[],

)

def _encrypt_str(self, s: str) -> ast.AST:

try:

data = s.encode('utf-8')

except UnicodeEncodeError:

return ast.Constant(value=s)

key = self._make_key()

return self._pool_ref(self._store_entry(data, key), self.dec_s)

def _encrypt_bytes(self, b: bytes) -> ast.AST:

key = self._make_key()

return self._pool_ref(self._store_entry(b, key), self.dec_b)

def build_pool_stmt(self) -> ast.stmt | None:

if not self.entries:

return None

entry_nodes = []

for data_chunks, key_chunks, data_order, key_order, rotation, mode in self.entries:

entry_nodes.append(

ast.Tuple(

elts=[

self._bytes_tuple(data_chunks),

self._bytes_tuple(key_chunks),

self._int_tuple(data_order),

self._int_tuple(key_order),

ast.Constant(value=rotation),

ast.Constant(value=mode),

],

ctx=ast.Load(),

)

)

return ast.Assign(

targets=[ast.Name(id=self.pool_name, ctx=ast.Store())],

value=ast.Tuple(elts=entry_nodes, ctx=ast.Load()),

)

def build_decrypt_helper(decrypt_str_name: str, decrypt_bytes_name: str) -> list[ast.stmt]:

src = f'''

def _pw_join_chunks(_chunks, _order):

return b''.join(_chunks[_i] for _i in _order)

def _pw_unrotate(_data, _amount):

if not _data:

return _data

_amount %= len(_data)

return _data[-_amount:] + _data[:-_amount] if _amount else _data

def _pw_xor_a(_data, _key):

return bytes(_b ^ _key[_i % len(_key)] for _i, _b in enumerate(_data))

def _pw_xor_b(_data, _key):

_out = bytearray(len(_data))

for _i, _b in enumerate(_data):

_out[_i] = _b ^ _key[_i % len(_key)]

return bytes(_out)

def _pw_xor_c(_data, _key):

return bytes(map(lambda _p: _p[1] ^ _key[_p[0] % len(_key)], enumerate(_data)))

def _pw_decode_entry(_pool, _idx):

_d, _k, _do, _ko, _rot, _mode = _pool[_idx]

_data = _pw_unrotate(_pw_join_chunks(_d, _do), _rot)

_key = _pw_join_chunks(_k, _ko)

if _mode == 1:

return _pw_xor_b(_data, _key)

if _mode == 2:

return _pw_xor_c(_data, _key)

return _pw_xor_a(_data, _key)

def {decrypt_bytes_name}(_pool, _idx):

return _pw_decode_entry(_pool, _idx)

def {decrypt_str_name}(_pool, _idx):

return _pw_decode_entry(_pool, _idx).decode()

'''

return ast.parse(src).body