65 lines
2.1 KiB
Python
65 lines
2.1 KiB
Python
from __future__ import print_function, absolute_import, unicode_literals
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from attr import attrs, attrib
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from attr.validators import provides, instance_of
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from zope.interface import implementer
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from automat import MethodicalMachine
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from . import _interfaces
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from ._key import derive_phase_key, encrypt_data
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@attrs
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@implementer(_interfaces.ISend)
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class Send(object):
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_side = attrib(validator=instance_of(type(u"")))
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_timing = attrib(validator=provides(_interfaces.ITiming))
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m = MethodicalMachine()
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set_trace = m.setTrace
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def __attrs_post_init__(self):
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self._queue = []
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def wire(self, mailbox):
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self._M = _interfaces.IMailbox(mailbox)
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@m.state(initial=True)
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def S0_no_key(self): pass # pragma: no cover
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@m.state(terminal=True)
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def S1_verified_key(self): pass # pragma: no cover
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# from Receive
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@m.input()
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def got_verified_key(self, key): pass
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# from Boss
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@m.input()
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def send(self, phase, plaintext): pass
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@m.output()
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def queue(self, phase, plaintext):
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assert isinstance(phase, type("")), type(phase)
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assert isinstance(plaintext, type(b"")), type(plaintext)
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self._queue.append((phase, plaintext))
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@m.output()
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def record_key(self, key):
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self._key = key
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@m.output()
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def drain(self, key):
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del key
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for (phase, plaintext) in self._queue:
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self._encrypt_and_send(phase, plaintext)
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self._queue[:] = []
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@m.output()
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def deliver(self, phase, plaintext):
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assert isinstance(phase, type("")), type(phase)
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assert isinstance(plaintext, type(b"")), type(plaintext)
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self._encrypt_and_send(phase, plaintext)
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def _encrypt_and_send(self, phase, plaintext):
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assert self._key
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data_key = derive_phase_key(self._key, self._side, phase)
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encrypted = encrypt_data(data_key, plaintext)
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self._M.add_message(phase, encrypted)
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S0_no_key.upon(send, enter=S0_no_key, outputs=[queue])
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S0_no_key.upon(got_verified_key, enter=S1_verified_key,
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outputs=[record_key, drain])
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S1_verified_key.upon(send, enter=S1_verified_key, outputs=[deliver])
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