78 lines
2.2 KiB
Python
78 lines
2.2 KiB
Python
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import struct
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from nacl.secret import SecretBox
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from .util import bytes_to_long, long_to_bytes
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NONCE_SIZE = 24
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HEADER_LENGTH = 2 + 16 + 16
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MAX_SEGMENT_SIZE = 4 * 1024
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TERMINATION_HEADER = (b'\x00' * HEADER_LENGTH)
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MAX_NONCE = (8 * NONCE_SIZE)
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def inc_nonce(nonce):
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num = bytes_to_long(nonce) + 1
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if num > 2**MAX_NONCE:
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num = 0
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bnum = long_to_bytes(num)
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bnum = b'\x00' * (NONCE_SIZE - len(bnum)) + bnum
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return bnum
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def get_stream_pair(reader, writer, **kwargs):
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shared_secret = kwargs.pop('shared_secret')
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return UnboxStream(reader, shared_secret, **kwargs), BoxStream(writer, shared_secret, **kwargs)
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class UnboxStream(object):
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def __init__(self, reader, shared_secret, **key_data):
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self.reader = reader
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self.decrypt_key = key_data.get('decrypt_key')
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self.decrypt_nonce = key_data.get('decrypt_nonce')
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async def process(self):
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while True:
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data = await self.reader.read(HEADER_LENGTH)
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if not data:
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break
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box = SecretBox(self.decrypt_key)
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header = box.decrypt(data, self.decrypt_nonce)
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if header == TERMINATION_HEADER:
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return
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length = struct.unpack('>H', header[:2])[0]
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mac = header[2:]
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data = await self.reader.read(length)
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self.decrypt_nonce = inc_nonce(self.decrypt_nonce)
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body = box.decrypt(mac + data, self.decrypt_nonce)
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self.decrypt_nonce = inc_nonce(self.decrypt_nonce)
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yield body
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print('Disconnect')
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class BoxStream(object):
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def __init__(self, writer, shared_secret, **key_data):
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self.writer = writer
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self.encrypt_key = key_data.get('decrypt_key')
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self.encrypt_nonce = key_data.get('decrypt_nonce')
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async def write(self, data):
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box = SecretBox(self.encrypt_key)
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# XXX: This nonce logic is almost for sure wrong
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self.encrypt_nonce = inc_nonce(self.encrypt_nonce)
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body = box.encrypt(data, self.encrypt_nonce)
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header = struct.pack('>H', len(body)) + body[:16]
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self.writer.write(box.encrypt(header, self.encrypt_nonce))
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self.encrypt_nonce = inc_nonce(self.encrypt_nonce)
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self.writer.write(body)
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