mirror of
https://github.com/bikini/patchwork
synced 2026-06-27 08:08:41 +00:00
bikini
49 lines
1.4 KiB
Python
49 lines
1.4 KiB
Python
from __future__ import annotations
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import hashlib
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import random
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def keystream(key: bytes, length: int) -> bytes:
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out = bytearray()
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ctr = 0
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while len(out) < length:
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out.extend(hashlib.sha256(key + ctr.to_bytes(8, 'big')).digest())
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ctr += 1
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return bytes(out[:length])
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def stream_xor(data: bytes, key: bytes) -> bytes:
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ks = keystream(key, len(data))
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return bytes((a ^ b for a, b in zip(data, ks)))
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def make_perm(key: bytes) -> bytes:
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seed = int.from_bytes(hashlib.sha256(key).digest(), 'big')
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rng = random.Random(seed)
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perm = list(range(256))
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rng.shuffle(perm)
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return bytes(perm)
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def invert_perm(perm: bytes) -> bytes:
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inv = bytearray(256)
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for i, p in enumerate(perm):
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inv[p] = i
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return bytes(inv)
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def perm_apply(data: bytes, key: bytes) -> bytes:
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perm = make_perm(key)
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return bytes((perm[b] for b in data))
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def perm_invert(data: bytes, key: bytes) -> bytes:
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inv = invert_perm(make_perm(key))
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return bytes((inv[b] for b in data))
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def _rot_left(b: int, n: int) -> int:
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n &= 7
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if not n:
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return b
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return (b << n | b >> 8 - n) & 255
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def rot_apply(data: bytes, key: bytes) -> bytes:
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return bytes((_rot_left(b, key[i % len(key)]) for i, b in enumerate(data)))
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def rot_invert(data: bytes, key: bytes) -> bytes:
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return bytes((_rot_left(b, -key[i % len(key)] & 7) for i, b in enumerate(data)))
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