state_channel.py

class Channel:

    
    def __init__(self, sender, recipient, deposit):
        self.sender = to_checksum_address(sender)
        self.recipient = to_checksum_address(recipient)
        self.deposit = deposit
        self.signatures = {}
    
    
    def close_channel(self, h, v, r, s, value):
        """
        Function recreating Matthew Di Ferrante's closure of a state channel in Python

        Args:
            h: The Keccak hash of the msg
            v: The "v" parameter derived from the hashed and signed message (ethereum.utils.ecsign)
            r: The "r" parameter derived from the hashed and signed message (ethereum.utils.ecsign)
            s: The "s" parameter derived from the hashed and signed message (ethereum.utils.ecsign)
            value: the 

        Returns:
            Address of the message signer as a hexidecimal string
        """
        
        # Recover the message signer's address
        # v, r, and s are specific to the message that was hashed and signed.
        # Changing any of these parameters produces a different address 
        # This also proves that h is the hashed message that was signed to produce v, r, and s
        signer = ecrecover(h, v, r, s)
        
        # Ensure that the signer is either the sender (Bob) or recipient (Alice) of the channel's ETH
        if (signer != self.recipient) and (signer != self.sender):
            assert False
        
        # Ensure that that value matches the signed message
        # Including the contract's hash ensures that the signed message can only be used in this channel
        proof = keccak(str(self.__hash__()) + value)
        if (proof != h):
            assert False
        
        # If this is the first time associate the proof with the first signer
        # Doesn't matter if Alice submits her signature or Bob's signature first
        # Or even if Bob submits his own signature first
        if not self.signatures.get(proof):
            self.signatures[proof] = signer
        # Continue from here only when the second signature makes an appearance
        elif (self.signatures.get(proof) != signer):
            # -- psuedo-code -- 
            # send(value, to=self.recipient)
            # send(self.deposit - value, to=self.sender)
            # self.destruct()
            print('Success')