def check_covert_component(msg, round_pubkey, component_feerate):
message_hash = sha256(msg.component)
check(len(msg.signature) == 64, "bad message signature")
check(schnorr.verify(round_pubkey, msg.signature, message_hash), "bad message signature")
cmsg = proto_strict_parse(pb.Component(), msg.component)
check(len(cmsg.salt_commitment) == 32, "bad salt commitment")
ctype = cmsg.WhichOneof('component')
if ctype == 'input':
inp = cmsg.input
check(len(inp.prev_txid) == 32, "bad txid")
check( (len(inp.pubkey) == 33 and inp.pubkey[0] in (2,3))
or (len(inp.pubkey) == 65 and inp.pubkey[0] == 4),
"bad pubkey")
sort_key = ('i', inp.prev_txid[::-1], inp.prev_index, cmsg.salt_commitment)
elif ctype == 'output':
out = cmsg.output
atype, addr = get_address_from_output_script(out.scriptpubkey)
check(atype == TYPE_ADDRESS, "output is not address")
check(out.amount >= dust_limit(len(out.scriptpubkey)), "dust output")
sort_key = ('o', out.amount, out.scriptpubkey, cmsg.salt_commitment)
elif ctype == 'blank':
sort_key = ('b', cmsg.salt_commitment)
else:
raise ValidationError('missing component details')
# Note: for each sort type we use salt_commitment as a tie-breaker, just to
# make sure that original ordering is forgotten. Of course salt_commitment
# doesn't have to be unique, but it's unique for all honest players.
return sort_key, component_contrib(cmsg, component_feerate)
def tx_from_components(all_components, session_hash):
""" Returns the tx and a list of indices matching inputs with components"""
input_indices = []
assert len(session_hash) == 32
if Protocol.FUSE_ID is None:
prefix = []
else:
assert len(Protocol.FUSE_ID) == 4
prefix = [4, *Protocol.FUSE_ID]
inputs = []
outputs = [
(TYPE_SCRIPT,
ScriptOutput(bytes([OpCodes.OP_RETURN, *prefix, 32]) + session_hash),
0)
]
for i, compser in enumerate(all_components):
comp = pb.Component()
comp.ParseFromString(compser)
ctype = comp.WhichOneof('component')
if ctype == 'input':
inp = comp.input
if len(inp.prev_txid) != 32:
raise FusionError("bad component prevout")
inputs.append(
dict(address=Address.from_P2PKH_hash(hash160(inp.pubkey)),
prevout_hash=inp.prev_txid[::-1].hex(),
prevout_n=inp.prev_index,
num_sig=1,
signatures=[None],
type='p2pkh',
x_pubkeys=[inp.pubkey.hex()],
pubkeys=[inp.pubkey.hex()],
sequence=0xffffffff,
value=inp.amount))
input_indices.append(i)
elif ctype == 'output':
out = comp.output
atype, addr = get_address_from_output_script(out.scriptpubkey)
if atype != TYPE_ADDRESS:
raise FusionError("bad component address")
outputs.append((TYPE_ADDRESS, addr, out.amount))
elif ctype != 'blank':
raise FusionError("bad component")
tx = Transaction.from_io(inputs, outputs, locktime=0, sign_schnorr=True)
tx.version = 1
return tx, input_indices