Add support for spending timelocked UTXOs

The cryptoengine class BTC_Timelocked_P2WSH now implements
sign_transaction() which can be used to spend timelocked UTXOs.

FidelityBondMixin.is_timelocked_path() is now used outside the class
so its leading underscore has been removed.

jmclient/jmclient/cryptoengine.py

@@ -332,14 +332,19 @@ class BTC_Timelocked_P2WSH(BTCEngine):
         return btc.bin_to_b58check(priv, cls.WIF_PREFIX)
 
     @classmethod
-    def sign_transaction(cls, tx, index, privkey, amount,
+    def sign_transaction(cls, tx, index, privkey_locktime, amount,
                          hashcode=btc.SIGHASH_ALL, **kwargs):
-        raise Exception("not implemented yet")
+        assert amount is not None
 
-    @classmethod
-    def sign_transaction(cls, tx, index, privkey, amount,
-                         hashcode=btc.SIGHASH_ALL, **kwargs):
-        raise RuntimeError("Cannot spend from watch-only wallets")
+        privkey, locktime = privkey_locktime
+        privkey = hexlify(privkey).decode()
+        pubkey = btc.privkey_to_pubkey(privkey)
+        pubkey = unhexlify(pubkey)
+        redeem_script = cls.pubkey_to_script_code((pubkey, locktime))
+        tx = btc.serialize(tx)
+        sig = btc.get_p2sh_signature(tx, index, redeem_script, privkey,
+            amount)
+        return btc.apply_freeze_signature(tx, index, redeem_script, sig)
 
 class BTC_Watchonly_Timelocked_P2WSH(BTC_Timelocked_P2WSH):
 
@@ -368,7 +373,7 @@ class BTC_Watchonly_Timelocked_P2WSH(BTC_Timelocked_P2WSH):
     @classmethod
     def sign_transaction(cls, tx, index, privkey, amount,
                          hashcode=btc.SIGHASH_ALL, **kwargs):
-        raise Exception("not implemented yet")
+        raise RuntimeError("Cannot spend from watch-only wallets")
 
 class BTC_Watchonly_P2SH_P2WPKH(BTC_P2SH_P2WPKH):
 
@@ -392,6 +397,11 @@ class BTC_Watchonly_P2SH_P2WPKH(BTC_P2SH_P2WPKH):
         return super(BTC_Watchonly_P2SH_P2WPKH, cls).derive_bip32_pub_export(
             master_key, BTC_Watchonly_Timelocked_P2WSH.get_watchonly_path(path))
 
+    @classmethod
+    def sign_transaction(cls, tx, index, privkey, amount,
+                         hashcode=btc.SIGHASH_ALL, **kwargs):
+        raise RuntimeError("Cannot spend from watch-only wallets")
+
 ENGINES = {
     TYPE_P2PKH: BTC_P2PKH,
     TYPE_P2SH_P2WPKH: BTC_P2SH_P2WPKH,

jmclient/jmclient/taker_utils.py

@@ -117,12 +117,28 @@ def direct_send(wallet_service, amount, mixdepth, destination, answeryes=False,
         change_addr = wallet_service.get_internal_addr(mixdepth)
         outs.append({"value": changeval, "address": change_addr})
 
+    #compute transaction locktime, has special case for spending timelocked coins
+    tx_locktime = compute_tx_locktime()
+    if mixdepth == FidelityBondMixin.FIDELITY_BOND_MIXDEPTH and \
+            isinstance(wallet_service.wallet, FidelityBondMixin):
+        for outpoint, utxo in utxos.items():
+            path = wallet_service.script_to_path(
+                wallet_service.addr_to_script(utxo["address"]))
+            if not FidelityBondMixin.is_timelocked_path(path):
+                continue
+            path_locktime = path[-1]
+            tx_locktime = max(tx_locktime, path_locktime+1)
+            #compute_tx_locktime() gives a locktime in terms of block height
+            #timelocked addresses use unix time instead
+            #OP_CHECKLOCKTIMEVERIFY can only compare like with like, so we
+            #must use unix time as the transaction locktime
+
     #Now ready to construct transaction
     log.info("Using a fee of : " + amount_to_str(fee_est) + ".")
     if amount != 0:
         log.info("Using a change value of: " + amount_to_str(changeval) + ".")
     txsigned = sign_tx(wallet_service, make_shuffled_tx(
-        list(utxos.keys()), outs, False, 2, compute_tx_locktime()), utxos)
+        list(utxos.keys()), outs, False, 2, tx_locktime), utxos)
     log.info("Got signed transaction:\n")
     log.info(pformat(txsigned))
     tx = serialize(txsigned)

jmclient/jmclient/wallet.py

@@ -1694,7 +1694,7 @@ class FidelityBondMixin(object):
         return timenumber
 
     @classmethod
-    def _is_timelocked_path(cls, path):
+    def is_timelocked_path(cls, path):
         return len(path) > 4 and path[4] == cls.BIP32_TIMELOCK_ID
 
     def get_xpub_from_fidelity_bond_master_pub_key(cls, mpk):
@@ -1737,7 +1737,7 @@ class FidelityBondMixin(object):
         return (cls.BIP32_EXT_ID, cls.BIP32_INT_ID, cls.BIP32_TIMELOCK_ID, cls.BIP32_BURN_ID)
 
     def _get_priv_from_path(self, path):
-        if self._is_timelocked_path(path):
+        if self.is_timelocked_path(path):
             key_path = path[:-1]
             locktime = path[-1]
             engine = self._TIMELOCK_ENGINE
@@ -1766,7 +1766,7 @@ class FidelityBondMixin(object):
     refering to the pubkey plus the timelock value which together are needed to create the address
     """
     def get_path_repr(self, path):
-        if self._is_timelocked_path(path) and len(path) == 7:
+        if self.is_timelocked_path(path) and len(path) == 7:
             return super(FidelityBondMixin, self).get_path_repr(path[:-1]) +\
                  ":" + str(path[-1])
         else:
@@ -1785,7 +1785,7 @@ class FidelityBondMixin(object):
             ))
 
     def get_details(self, path):
-        if self._is_timelocked_path(path):
+        if self.is_timelocked_path(path):
             return self._get_mixdepth_from_path(path), path[-3], path[-2]
         else:
             return super(FidelityBondMixin, self).get_details(path)