Extract secret-handshake into separate lib
This commit is contained in:
Pedro Ferreira
parent
761b503c95
commit
21af5fba09
@ -1,3 +1,4 @@
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pynacl
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simplejson
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pytest
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secret-handshake
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@ -1,77 +0,0 @@
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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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@ -1,7 +1,7 @@
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import struct
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from enum import Enum
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from .shs.socket import SHSClient, SHSServer
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from secret_handshake import SHSClient, SHSServer
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import simplejson
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@ -33,17 +33,25 @@ class PSMessage(object):
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class PSSocket(object):
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async def read(self):
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while True:
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try:
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header = await self.connection.read().__anext__()
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body = await self.connection.read().__anext__()
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header = await self.connection.read()
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if not header:
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return
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body = await self.connection.read()
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flags, length, req = struct.unpack('>BIi', header)
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yield PSMessage(bool(flags & 0x08), bool(flags & 0x04), flags & 0x03, body)
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return PSMessage(bool(flags & 0x08), bool(flags & 0x04), flags & 0x03, body)
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except StopAsyncIteration:
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await self.connection.disconnect()
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break
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return None
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async def write(self, type_, data, req=0):
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async def __aiter__(self):
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while True:
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data = await self.read()
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if data is None:
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return
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yield data
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def write(self, type_, data, req=0):
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type_ = PSMessageType[type_]
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if type_ == PSMessageType.JSON:
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data = simplejson.dumps(data)
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@ -51,27 +59,29 @@ class PSSocket(object):
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# XXX: Not yet handling flags that nicely
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header = struct.pack('>BIi', 0x08 | type_.value, len(data), req)
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await self.connection.write(header)
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await self.connection.write(data.encode('utf-8'))
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self.connection.write(header)
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self.connection.write(data.encode('utf-8'))
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class PSClient(PSSocket):
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def __init__(self, host, port, client_kp, server_pub_key, ephemeral_key=None, application_key=None):
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def __init__(self, host, port, client_kp, server_pub_key, ephemeral_key=None, application_key=None, loop=None):
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self.connection = SHSClient(host, port, client_kp, server_pub_key, ephemeral_key=ephemeral_key,
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application_key=application_key)
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application_key=application_key, loop=loop)
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self.loop = loop
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async def connect(self, loop=None):
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await self.connection.connect(loop=loop)
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def connect(self):
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self.connection.connect()
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class PSServer(PSSocket):
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def __init__(self, host, port, client_kp, application_key=None):
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self.connection = SHSServer(host, port, client_kp, application_key=application_key)
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def __init__(self, host, port, client_kp, application_key=None, loop=None):
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self.connection = SHSServer(host, port, client_kp, application_key=application_key, loop=loop)
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self.loop = loop
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async def listen(self, loop=None):
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await self.connection.listen(loop=loop)
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def listen(self):
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self.connection.listen()
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def on_connect(self, handler):
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def on_connect(self, cb):
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async def _on_connect():
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await handler(self)
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self.connection._on_connect = _on_connect
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await cb(self)
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self.connection.on_connect(_on_connect)
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@ -1,4 +0,0 @@
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from .crypto import SHSClientCrypto, SHSServerCrypto
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from .socket import SHSClient, SHSServer
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__all__ = ('SHSClient', 'SHSClientCrypto', 'SHSServer', 'SHSServerCrypto')
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@ -1,160 +0,0 @@
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import hashlib
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import hmac
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from base64 import b64decode
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from nacl.bindings import crypto_scalarmult, crypto_box_afternm, crypto_box_open_afternm
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from nacl.exceptions import CryptoError
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from nacl.public import PrivateKey
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from nacl.signing import VerifyKey
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APPLICATION_KEY = b64decode('1KHLiKZvAvjbY1ziZEHMXawbCEIM6qwjCDm3VYRan/s=')
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class SHSError(Exception):
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"""A SHS exception."""
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pass
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class SHSCryptoBase(object):
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def __init__(self, local_key, ephemeral_key=None, application_key=None):
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self.local_key = local_key
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self.application_key = application_key or APPLICATION_KEY
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self._reset_keys(ephemeral_key or PrivateKey.generate())
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def _reset_keys(self, ephemeral_key):
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self.local_ephemeral_key = ephemeral_key
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self.local_app_hmac = (hmac.new(self.application_key, bytes(ephemeral_key.public_key), digestmod='sha512')
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.digest()[:32])
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def generate_challenge(self):
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"""Generate and return a challenge to be sent to the server."""
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return self.local_app_hmac + bytes(self.local_ephemeral_key.public_key)
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def verify_challenge(self, data):
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"""Verify the correctness of challenge sent from the client."""
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assert len(data) == 64
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sent_hmac, remote_ephemeral_key = data[:32], data[32:]
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h = hmac.new(self.application_key, remote_ephemeral_key, digestmod='sha512')
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self.remote_app_hmac = h.digest()[:32]
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ok = self.remote_app_hmac == sent_hmac
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if ok:
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# this is (a * b)
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self.shared_secret = crypto_scalarmult(bytes(self.local_ephemeral_key), remote_ephemeral_key)
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self.remote_ephemeral_key = remote_ephemeral_key
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# this is hash(a * b)
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self.shared_hash = hashlib.sha256(self.shared_secret).digest()
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return ok
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def clean(self, new_ephemeral_key=None):
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self._reset_keys(new_ephemeral_key or PrivateKey.generate())
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self.shared_secret = None
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self.shared_hash = None
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self.remote_ephemeral_key = None
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def get_box_keys(self):
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shared_secret = hashlib.sha256(self.box_secret).digest()
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return {
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'shared_secret': shared_secret,
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'encrypt_key': hashlib.sha256(shared_secret + bytes(self.remote_pub_key)).digest(),
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'decrypt_key': hashlib.sha256(shared_secret + bytes(self.local_key.verify_key)).digest(),
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'encrypt_nonce': self.remote_app_hmac[:24],
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'decrypt_nonce': self.local_app_hmac[:24]
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}
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class SHSServerCrypto(SHSCryptoBase):
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def verify_client_auth(self, data):
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assert len(data) == 112
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a_bob = crypto_scalarmult(bytes(self.local_key.to_curve25519_private_key()), self.remote_ephemeral_key)
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box_secret = hashlib.sha256(self.application_key + self.shared_secret + a_bob).digest()
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self.hello = crypto_box_open_afternm(data, b'\x00' * 24, box_secret)
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signature, public_key = self.hello[:64], self.hello[64:]
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signed = self.application_key + bytes(self.local_key.verify_key) + self.shared_hash
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pkey = VerifyKey(public_key)
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# will raise an exception if verification fails
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pkey.verify(signed, signature)
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self.remote_pub_key = pkey
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b_alice = crypto_scalarmult(bytes(self.local_ephemeral_key),
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bytes(self.remote_pub_key.to_curve25519_public_key()))
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self.box_secret = hashlib.sha256(self.application_key + self.shared_secret + a_bob + b_alice).digest()[:32]
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return True
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def generate_accept(self):
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okay = self.local_key.sign(self.application_key + self.hello + self.shared_hash).signature
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d = crypto_box_afternm(okay, b'\x00' * 24, self.box_secret)
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return d
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def clean(self, new_ephemeral_key=None):
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super(SHSServerCrypto, self).clean(new_ephemeral_key=new_ephemeral_key)
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self.hello = None
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self.local_lterm_shared = None
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class SHSClientCrypto(SHSCryptoBase):
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"""An object that encapsulates all the SHS client-side crypto.
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:param local_key: the :class:`ssb.keys.KeyPair` used by the client
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:param local_ephemeral_key: a fresh local :class:`nacl.public.PrivateKey`
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:param server_pub_key: the server's public key (``byte`` string)
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:param application_key: the unique application key (``byte`` string), defaults to SSB's
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"""
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def __init__(self, local_key, server_pub_key, ephemeral_key, application_key=None):
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super(SHSClientCrypto, self).__init__(local_key, ephemeral_key, application_key)
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self.remote_pub_key = VerifyKey(server_pub_key)
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def verify_server_challenge(self, data):
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"""Verify the correctness of challenge sent from the server."""
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# TODO: use super.verify_challenge and add extra logic
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return super(SHSClientCrypto, self).verify_challenge(data)
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def generate_client_auth(self):
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"""Generate box[K|a*b|a*B](H)"""
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curve_pkey = self.remote_pub_key.to_curve25519_public_key()
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# remote_lterm_shared is (a * B)
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remote_lterm_shared = crypto_scalarmult(bytes(self.local_ephemeral_key), bytes(curve_pkey))
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self.remote_lterm_shared = remote_lterm_shared
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# this shall be hash(K | a * b | a * B)
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box_secret = hashlib.sha256(self.application_key + self.shared_secret + remote_lterm_shared).digest()
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# and message_to_box will correspond to H = sign(A)[K | Bp | hash(a * b)] | Ap
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signed_message = self.local_key.sign(self.application_key + bytes(self.remote_pub_key) + self.shared_hash)
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message_to_box = signed_message.signature + bytes(self.local_key.verify_key)
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self.client_auth = message_to_box
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nonce = b"\x00" * 24
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# return box(K | a * b | a * B)[H]
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return crypto_box_afternm(message_to_box, nonce, box_secret)
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def verify_server_accept(self, data):
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"""Verify that the server's accept message is sane"""
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curve_lkey = self.local_key.to_curve25519_private_key()
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# local_lterm_shared is (A * b)
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local_lterm_shared = crypto_scalarmult(bytes(curve_lkey), self.remote_ephemeral_key)
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self.local_lterm_shared = local_lterm_shared
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# this is hash(K | a * b | a * B | A * b)
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self.box_secret = hashlib.sha256(self.application_key + self.shared_secret + self.remote_lterm_shared +
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local_lterm_shared).digest()
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nonce = b"\x00" * 24
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try:
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# let's use the box secret to unbox our encrypted message
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signature = crypto_box_open_afternm(data, nonce, self.box_secret)
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except CryptoError:
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raise SHSError('Error decrypting server acceptance message')
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# we should have received sign(B)[K | H | hash(a * b)]
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# let's see if that signature can verify the reconstructed data on our side
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self.remote_pub_key.verify(self.application_key + self.client_auth + self.shared_hash, signature)
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return True
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def clean(self, new_ephemeral_key=None):
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super(SHSClientCrypto, self).clean(new_ephemeral_key=new_ephemeral_key)
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self.remote_lterm_shared = None
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self.local_lterm_shared = None
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@ -1,88 +0,0 @@
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from asyncio import open_connection, start_server
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from ..boxstream import get_stream_pair
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from .crypto import SHSClientCrypto, SHSServerCrypto
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class SHSClientException(Exception):
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pass
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class SHSSocket(object):
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async def read(self):
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async for msg in self.read_stream.process():
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yield msg
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async def write(self, data):
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await self.write_stream.write(data)
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async def disconnect(self):
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self.writer.close()
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class SHSServer(SHSSocket):
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def __init__(self, host, port, server_kp, application_key=None):
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self.host = host
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self.port = port
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self.crypto = SHSServerCrypto(server_kp.private_key, application_key=application_key)
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self._on_connect = None
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async def _handshake(self, reader, writer):
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data = await reader.read(64)
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if not self.crypto.verify_challenge(data):
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raise SHSClientException('Client challenge is not valid')
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writer.write(self.crypto.generate_challenge())
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data = await reader.read(112)
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if not self.crypto.verify_client_auth(data):
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raise SHSClientException('Client auth is not valid')
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writer.write(self.crypto.generate_accept())
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async def handle_connection(self, reader, writer):
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self.crypto.clean()
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await self._handshake(reader, writer)
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keys = self.crypto.get_box_keys()
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self.crypto.clean()
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self.read_stream, self.write_stream = get_stream_pair(reader, writer, **keys)
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self.writer = writer
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if self._on_connect:
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await self._on_connect()
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async def listen(self, loop=None):
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await start_server(self.handle_connection, self.host, self.port, loop=loop)
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class SHSClient(SHSSocket):
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def __init__(self, host, port, client_kp, server_pub_key, ephemeral_key=None, application_key=None):
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self.host = host
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self.port = port
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self.crypto = SHSClientCrypto(client_kp.private_key, server_pub_key, ephemeral_key=ephemeral_key,
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application_key=application_key)
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async def _handshake(self, reader, writer):
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writer.write(self.crypto.generate_challenge())
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data = await reader.read(64)
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if not self.crypto.verify_server_challenge(data):
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raise SHSClientException('Server challenge is not valid')
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writer.write(self.crypto.generate_client_auth())
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data = await reader.read(80)
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if not self.crypto.verify_server_accept(data):
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raise SHSClientException('Server accept is not valid')
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async def connect(self, loop=None):
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reader, writer = await open_connection(self.host, self.port, loop=loop)
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await self._handshake(reader, writer)
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keys = self.crypto.get_box_keys()
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self.crypto.clean()
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self.read_stream, self.write_stream = get_stream_pair(reader, writer, **keys)
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self.writer = writer
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@ -1,17 +0,0 @@
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import hashlib
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import pytest
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from nacl.public import PrivateKey
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from ssb.shs import SecretHandShake
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@pytest.fixture()
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def appkey():
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return hashlib.sha256(b'app_key').digest()
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def test_client_challenge(appkey):
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pk = PrivateKey.generate()
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shs = SecretHandShake(pk, application_key=appkey)
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assert shs.client_challenge
|
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@ -1,19 +1,28 @@
|
||||
import os
|
||||
from asyncio import get_event_loop
|
||||
from base64 import b64decode
|
||||
|
||||
from ssb.keys import KeyPair
|
||||
import yaml
|
||||
from nacl.signing import SigningKey
|
||||
|
||||
from ssb.packet_stream import PSClient
|
||||
|
||||
server_pub_key = b64decode('--- your public key ---')
|
||||
|
||||
with open(os.path.expanduser('~/.ssb/secret')) as f:
|
||||
config = yaml.load(f)
|
||||
|
||||
|
||||
server_pub_key = b64decode(config['public'][:-8])
|
||||
|
||||
|
||||
async def main(loop):
|
||||
await packet_stream.connect(loop)
|
||||
async for msg in packet_stream.read():
|
||||
async for msg in packet_stream:
|
||||
print(msg)
|
||||
print('bye')
|
||||
|
||||
packet_stream = PSClient('127.0.0.1', 8008, KeyPair(), server_pub_key)
|
||||
loop = get_event_loop()
|
||||
|
||||
packet_stream = PSClient('127.0.0.1', 8008, SigningKey.generate(), server_pub_key, loop=loop)
|
||||
packet_stream.connect()
|
||||
loop.run_until_complete(main(loop))
|
||||
loop.close()
|
||||
|
||||
@ -1,19 +1,20 @@
|
||||
import os
|
||||
from asyncio import get_event_loop
|
||||
from base64 import b64decode
|
||||
|
||||
from ssb.keys import KeyPair
|
||||
import yaml
|
||||
from nacl.signing import SigningKey
|
||||
|
||||
from ssb.packet_stream import PSServer
|
||||
|
||||
|
||||
priv_key = b64decode('--- your private key ---')
|
||||
|
||||
|
||||
async def main(loop):
|
||||
await packet_stream.listen(loop)
|
||||
with open(os.path.expanduser('~/.ssb/secret')) as f:
|
||||
config = yaml.load(f)
|
||||
|
||||
|
||||
async def on_connect(server):
|
||||
await server.write('JSON', {"name": ["createHistoryStream"],
|
||||
server.write('JSON', {
|
||||
"name": ["createHistoryStream"],
|
||||
"args": [{
|
||||
"id": "@/Odg52x38pt7OivNnxK1Lm+H/+x6yV4DhMeXHBQRYc0=.ed25519",
|
||||
"seq": 9,
|
||||
@ -21,11 +22,15 @@ async def on_connect(server):
|
||||
"keys": False
|
||||
}],
|
||||
"type": "source"}, req=1)
|
||||
print(await server.read().__anext__())
|
||||
print(await server.read())
|
||||
server.write('JSON', {})
|
||||
|
||||
packet_stream = PSServer('127.0.0.1', 8008, KeyPair(priv_key[:32]))
|
||||
packet_stream.on_connect(on_connect)
|
||||
loop = get_event_loop()
|
||||
loop.run_until_complete(main(loop))
|
||||
|
||||
server_keypair = SigningKey(b64decode(config['private'][:-8])[:32])
|
||||
packet_stream = PSServer('127.0.0.1', 8008, server_keypair, loop=loop)
|
||||
packet_stream.on_connect(on_connect)
|
||||
packet_stream.listen()
|
||||
|
||||
loop.run_forever()
|
||||
loop.close()
|
||||
|
||||
Loading…
Reference in New Issue
Block a user