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Parse incoming and announce outgoing fidelity bond messages Fidelity bond proof messages will be checked and added to the internal database just like offers. Such messages are not announced in public but only directly to takers who ask for them, this is because the signature proofs must commmit to the maker's and taker's IRC nicknames in order to avoid replay attacks.master
chris-belcher
6 years ago
16 changed files with 504 additions and 32 deletions
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import struct |
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import base64 |
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import json |
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from jmbitcoin import ecdsa_sign, ecdsa_verify |
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from jmdaemon import import fidelity_bond_sanity_check |
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def assert_is_utxo(utxo): |
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assert len(utxo) == 2 |
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assert isinstance(utxo[0], bytes) |
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assert len(utxo[0]) == 32 |
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assert isinstance(utxo[1], int) |
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assert utxo[1] >= 0 |
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def get_cert_msg(cert_pub, cert_expiry): |
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return b'fidelity-bond-cert|' + cert_pub + b'|' + str(cert_expiry).encode('ascii') |
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class FidelityBond: |
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def __init__(self, utxo, utxo_pubkey, locktime, cert_expiry, |
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cert_privkey, cert_pubkey, cert_signature): |
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assert_is_utxo(utxo) |
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assert isinstance(utxo_pubkey, bytes) |
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assert isinstance(locktime, int) |
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assert isinstance(cert_expiry, int) |
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assert isinstance(cert_privkey, bytes) |
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assert isinstance(cert_pubkey, bytes) |
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assert isinstance(cert_signature, bytes) |
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self.utxo = utxo |
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self.utxo_pubkey = utxo_pubkey |
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self.locktime = locktime |
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self.cert_expiry = cert_expiry |
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self.cert_privkey = cert_privkey |
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self.cert_pubkey = cert_pubkey |
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self.cert_signature = cert_signature |
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def create_proof(self, maker_nick, taker_nick): |
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return FidelityBondProof( |
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maker_nick, taker_nick, self.cert_pubkey, self.cert_expiry, |
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self.cert_signature, self.utxo, self.utxo_pubkey, self.locktime) |
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def serialize(self): |
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return json.dumps([ |
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self.utxo, |
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self.utxo_pubkey, |
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self.locktime, |
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self.cert_expiry, |
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self.cert_privkey, |
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self.cert_pubkey, |
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self.cert_signature, |
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]) |
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@classmethod |
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def deserialize(cls, data): |
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return cls(*json.loads(data)) |
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class FidelityBondProof: |
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# nick_sig + cert_sig + cert_pubkey + cert_expiry + utxo_pubkey + txid + vout + timelock |
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# 72 + 72 + 33 + 2 + 33 + 32 + 4 + 4 = 252 bytes |
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SER_STUCT_FMT = '<72s72s33sH33s32sII' |
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def __init__(self, maker_nick, taker_nick, cert_pub, cert_expiry, |
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cert_sig, utxo, utxo_pub, locktime): |
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assert isinstance(maker_nick, str) |
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assert isinstance(taker_nick, str) |
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assert isinstance(cert_pub, bytes) |
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assert isinstance(cert_sig, bytes) |
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assert isinstance(utxo_pub, bytes) |
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assert isinstance(locktime, int) |
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assert_is_utxo(utxo) |
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self.maker_nick = maker_nick |
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self.taker_nick = taker_nick |
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self.cert_pub = cert_pub |
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self.cert_expiry = cert_expiry |
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self.cert_sig = cert_sig |
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self.utxo = utxo |
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self.utxo_pub = utxo_pub |
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self.locktime = locktime |
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@property |
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def nick_msg(self): |
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return (self.taker_nick + '|' + self.maker_nick).encode('ascii') |
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def create_proof_msg(self, cert_priv): |
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nick_sig = ecdsa_sign(self.nick_msg, cert_priv) |
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# FIXME: remove stupid base64 |
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nick_sig = base64.b64decode(nick_sig) |
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return self._serialize_proof_msg(nick_sig) |
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def _serialize_proof_msg(self, msg_signature): |
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msg_signature = msg_signature.rjust(72, b'\xff') |
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cert_sig = self.cert_sig.rjust(72, b'\xff') |
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fidelity_bond_data = struct.pack( |
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self.SER_STUCT_FMT, |
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msg_signature, |
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cert_sig, |
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self.cert_pub, |
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self.cert_expiry, |
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self.utxo_pub, |
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self.utxo[0], |
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self.utxo[1], |
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self.locktime |
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) |
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return base64.b64encode(fidelity_bond_data).decode('ascii') |
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@staticmethod |
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def _verify_signature(message, signature, pubkey): |
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# FIXME: remove stupid base64 |
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return ecdsa_verify(message, base64.b64encode(signature), pubkey) |
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@classmethod |
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def parse_and_verify_proof_msg(cls, maker_nick, taker_nick, data): |
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if not fidelity_bond_sanity_check.fidelity_bond_sanity_check(data): |
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raise ValueError("sanity check failed") |
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decoded_data = base64.b64decode(data) |
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unpacked_data = struct.unpack(cls.SER_STUCT_FMT, decoded_data) |
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try: |
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signature = unpacked_data[0][unpacked_data[0].index(b'\x30'):] |
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cert_sig = unpacked_data[1][unpacked_data[1].index(b'\x30'):] |
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except ValueError: |
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#raised if index() doesnt find the position |
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raise ValueError("der signature header not found") |
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proof = cls(maker_nick, taker_nick, unpacked_data[2], unpacked_data[3], |
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cert_sig, (unpacked_data[5], unpacked_data[6]), |
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unpacked_data[4], unpacked_data[7]) |
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cert_msg = get_cert_msg(proof.cert_pub, proof.cert_expiry) |
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if not cls._verify_signature(proof.nick_msg, signature, proof.cert_pub): |
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raise ValueError("nick sig does not verify") |
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if not cls._verify_signature(cert_msg, proof.cert_sig, proof.utxo_pub): |
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raise ValueError("cert sig does not verify") |
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return proof |
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@ -0,0 +1,12 @@
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import base64 |
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def fidelity_bond_sanity_check(proof): |
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try: |
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decoded_data = base64.b64decode(proof, validate=True) |
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if len(decoded_data) != 252: |
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return False |
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except Exception: |
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return False |
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return True |
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