mirror of
https://github.com/logos-blockchain/logos-blockchain-specs.git
synced 2026-01-09 16:43:10 +00:00
100 lines
4.0 KiB
Python
100 lines
4.0 KiB
Python
import random
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from dataclasses import dataclass
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import simpy
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from cryptography.hazmat.primitives import serialization
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from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey, X25519PublicKey
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from sphinx import SphinxPacket, Attachment
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from p2p import P2p
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class Node:
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INCENTIVE_TX_SIZE = 512
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REAL_PAYLOAD = b"BLOCK"
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COVER_PAYLOAD = b"COVER"
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PADDING_SEPARATOR = b'\x01'
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@dataclass
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class Parameters:
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num_mix_layers: int
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message_interval: int
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message_prob: float
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max_message_prep_time: int
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def __init__(self, id: int, env: simpy.Environment, p2p: P2p, params: Parameters):
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self.id = id
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self.env = env
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self.p2p = p2p
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self.private_key = X25519PrivateKey.generate()
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self.public_key = self.private_key.public_key()
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self.params = params
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self.action = self.env.process(self.send_message())
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def send_message(self):
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"""
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Creates/encapsulate a message and send it to the network through the mixnet
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"""
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while True:
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msg = self.create_message()
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# TODO: Use the realistic cover traffic emission rate
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yield self.env.timeout(2)
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self.log("Sending a message to the mixnet")
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self.env.process(self.p2p.broadcast(msg))
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def create_message(self) -> SphinxPacket:
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"""
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Creates a message using the Sphinx format
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@return:
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"""
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mixes = self.p2p.get_nodes(self.params.num_mix_layers)
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public_keys = [mix.public_key for mix in mixes]
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# TODO: replace with realistic tx
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incentive_txs = [Node.create_incentive_tx(mix.public_key) for mix in mixes]
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payload = random.choice([self.REAL_PAYLOAD, self.COVER_PAYLOAD])
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return SphinxPacket(public_keys, incentive_txs, payload)
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def receive_message(self, msg: SphinxPacket | bytes):
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"""
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Receives a message from the network, processes it,
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and forwards it to the next mix or the entire network if necessary.
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@param msg: the message to be processed
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"""
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# simulating network latency
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yield self.env.timeout(random.randint(0, 3))
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if isinstance(msg, SphinxPacket):
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msg, incentive_tx = msg.unwrap(self.private_key)
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if self.is_my_incentive_tx(incentive_tx):
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self.log("Receiving SphinxPacket. It's mine!")
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if msg.is_all_unwrapped():
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if msg.payload == self.REAL_PAYLOAD:
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# Pad the final msg to the same size as a SphinxPacket,
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# assuming that the final msg is going to be sent via secure channels (TLS, Noise, etc.)
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final_padded_msg = (msg.payload
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+ self.PADDING_SEPARATOR
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+ bytes(len(msg) - len(msg.payload) - len(self.PADDING_SEPARATOR)))
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self.env.process(self.p2p.broadcast(final_padded_msg))
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else:
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# TODO: use Poisson delay or something else
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yield self.env.timeout(random.randint(0, 5))
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self.env.process(self.p2p.broadcast(msg))
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else:
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self.log("Receiving SphinxPacket, but not mine")
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else:
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final_msg = msg[:msg.rfind(self.PADDING_SEPARATOR)]
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self.log("Received final message: %s" % final_msg)
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# TODO: This is a dummy logic
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@classmethod
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def create_incentive_tx(cls, mix_public_key: X25519PublicKey) -> Attachment:
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public_key = mix_public_key.public_bytes(encoding=serialization.Encoding.Raw, format=serialization.PublicFormat.Raw)
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public_key += bytes(cls.INCENTIVE_TX_SIZE - len(public_key))
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return Attachment(public_key)
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def is_my_incentive_tx(self, tx: Attachment) -> bool:
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return tx == Node.create_incentive_tx(self.public_key)
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def log(self, msg):
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print("Node:%d at %g: %s" % (self.id, self.env.now, msg)) |