mirror of
https://github.com/bikini/patchwork
synced 2026-06-27 08:08:41 +00:00
bikini
71 lines
2.4 KiB
Python
71 lines
2.4 KiB
Python
from __future__ import annotations
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import ast
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import random
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class NumberObfuscator(ast.NodeTransformer):
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def __init__(self, rng: random.Random, prob: float=0.85):
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self.rng = rng
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self.prob = prob
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def visit_Constant(self, node: ast.Constant) -> ast.AST:
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v = node.value
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if isinstance(v, bool):
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return node
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if isinstance(v, int):
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if self.rng.random() <= self.prob:
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return self._obfuscate(v)
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return node
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def visit_match_case(self, node: ast.match_case) -> ast.AST:
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if node.guard is not None:
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node.guard = self.visit(node.guard)
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node.body = [self.visit(stmt) for stmt in node.body]
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return node
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def _obfuscate(self, n: int) -> ast.AST:
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choices = ['xor', 'sum', 'shift', 'frombytes', 'affine', 'split']
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kind = self.rng.choice(choices)
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try:
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return getattr(self, f'_t_{kind}')(n)
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except Exception:
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return ast.Constant(value=n)
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def _t_xor(self, n: int) -> ast.AST:
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k = self.rng.randrange(1, 1 << 32)
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return self._parse_expr(f'(({n ^ k}) ^ {k})')
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def _t_sum(self, n: int) -> ast.AST:
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a = self.rng.randint(-(1 << 16), 1 << 16)
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return self._parse_expr(f'(({n - a}) + ({a}))')
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def _t_shift(self, n: int) -> ast.AST:
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if abs(n) >= 1 << 60:
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return self._t_xor(n)
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s = self.rng.randint(1, 8)
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return self._parse_expr(f'(({n} << {s}) >> {s})')
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def _t_frombytes(self, n: int) -> ast.AST:
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signed = n < 0
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bit_len = max(1, n.bit_length() + (1 if signed else 0))
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byte_len = (bit_len + 7) // 8
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try:
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data = n.to_bytes(byte_len, 'big', signed=signed)
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except OverflowError:
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return self._t_xor(n)
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signed_arg = 'True' if signed else 'False'
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return self._parse_expr(f"int.from_bytes({data!r}, 'big', signed={signed_arg})")
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def _t_affine(self, n: int) -> ast.AST:
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a = self.rng.randint(2, 64)
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b = self.rng.randint(-(1 << 12), 1 << 12)
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return self._parse_expr(f'((({n * a + b}) - ({b})) // {a})')
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def _t_split(self, n: int) -> ast.AST:
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p = self.rng.randint(-(1 << 16), 1 << 16)
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q = n - p
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return self._parse_expr(f'({p} + ({q}))')
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def _parse_expr(self, src: str) -> ast.AST:
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return ast.parse(src, mode='eval').body
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