47 lines
1.5 KiB
Python
47 lines
1.5 KiB
Python
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from . import _curve25519
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from hashlib import sha256
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import os
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# the curve25519 functions are really simple, and could be used without an
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# OOP layer, but it's a bit too easy to accidentally swap the private and
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# public keys that way.
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def _hash_shared(shared):
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return sha256(b"curve25519-shared:"+shared).digest()
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class Private:
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def __init__(self, secret=None, seed=None):
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if secret is None:
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if seed is None:
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secret = os.urandom(32)
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else:
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secret = sha256(b"curve25519-private:"+seed).digest()
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else:
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assert seed is None, "provide secret, seed, or neither, not both"
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if not isinstance(secret, bytes) or len(secret) != 32:
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raise TypeError("secret= must be 32-byte string")
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self.private = _curve25519.make_private(secret)
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def serialize(self):
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return self.private
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def get_public(self):
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return Public(_curve25519.make_public(self.private))
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def get_shared_key(self, public, hashfunc=None):
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if not isinstance(public, Public):
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raise ValueError("'public' must be an instance of Public")
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if hashfunc is None:
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hashfunc = _hash_shared
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shared = _curve25519.make_shared(self.private, public.public)
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return hashfunc(shared)
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class Public:
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def __init__(self, public):
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assert isinstance(public, bytes)
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assert len(public) == 32
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self.public = public
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def serialize(self):
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return self.public
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