Fix support for Namecoin and Dogecoin, add Zcash support

Closes #83

lib/coins.py

@@ -39,7 +39,7 @@ from hashlib import sha256
 import lib.util as util
 from lib.hash import Base58, hash160, double_sha256, hash_to_str
 from lib.script import ScriptPubKey
-from lib.tx import Deserializer, DeserializerSegWit
+from lib.tx import Deserializer, DeserializerSegWit, DeserializerAuxPow, DeserializerZcash
 
 Block = namedtuple("Block", "header transactions")
 
@@ -293,6 +293,23 @@ class Coin(object):
     def deserializer(cls):
         return Deserializer
 
+class CoinAuxPow(Coin):
+    # Set NAME and NET to avoid exception in Coin::lookup_coin_class
+    NAME = ""
+    NET = ""
+    STATIC_BLOCK_HEADERS = False
+
+    @classmethod
+    def header_hash(cls, header):
+        '''Given a header return hash'''
+        return double_sha256(header[:cls.BASIC_HEADER_SIZE])
+
+    @classmethod
+    def block_header(cls, block, height):
+        '''Return the AuxPow block header bytes'''
+        block = DeserializerAuxPow(block)
+        return block.read_header(height, cls.BASIC_HEADER_SIZE)
+
 
 class Bitcoin(Coin):
     NAME = "Bitcoin"
@@ -451,7 +468,7 @@ class LitecoinTestnetSegWit(LitecoinTestnet):
 
 
 # Source: namecoin.org
-class Namecoin(Coin):
+class Namecoin(CoinAuxPow):
     NAME = "Namecoin"
     SHORTNAME = "NMC"
     NET = "mainnet"
@@ -484,7 +501,7 @@ class NamecoinTestnet(Namecoin):
 
 # For DOGE there is disagreement across sites like bip32.org and
 # pycoin.  Taken from bip32.org and bitmerchant on github
-class Dogecoin(Coin):
+class Dogecoin(CoinAuxPow):
     NAME = "Dogecoin"
     SHORTNAME = "DOGE"
     NET = "mainnet"
@@ -682,3 +699,50 @@ class FairCoin(Coin):
             'timestamp': timestamp,
             'creatorId': creatorId,
         }
+
+
+class Zcash(Coin):
+    NAME = "Zcash"
+    SHORTNAME = "ZEC"
+    NET = "mainnet"
+    XPUB_VERBYTES = bytes.fromhex("0488b21e")
+    XPRV_VERBYTES = bytes.fromhex("0488ade4")
+    P2PKH_VERBYTE = bytes.fromhex("1CB8")
+    P2SH_VERBYTE = bytes.fromhex("1CBD")
+    WIF_BYTE = bytes.fromhex("80")
+    GENESIS_HASH = ('00040fe8ec8471911baa1db1266ea15d'
+                    'd06b4a8a5c453883c000b031973dce08')
+    STATIC_BLOCK_HEADERS = False
+    BASIC_HEADER_SIZE = 140 # Excluding Equihash solution
+    TX_COUNT = 329196
+    TX_COUNT_HEIGHT = 68379
+    TX_PER_BLOCK = 5
+    IRC_PREFIX = "E_"
+    IRC_CHANNEL = "#electrum-zcash"
+    RPC_PORT = 8232
+    REORG_LIMIT = 800
+
+    @classmethod
+    def electrum_header(cls, header, height):
+        version, = struct.unpack('<I', header[:4])
+        timestamp, bits = struct.unpack('<II', header[100:108])
+
+        return {
+            'block_height': height,
+            'version': version,
+            'prev_block_hash': hash_to_str(header[4:36]),
+            'merkle_root': hash_to_str(header[36:68]),
+            'timestamp': timestamp,
+            'bits': bits,
+            'nonce': hash_to_str(header[108:140]),
+        }
+
+    @classmethod
+    def block_header(cls, block, height):
+        '''Return the block header bytes'''
+        block = DeserializerZcash(block)
+        return block.read_header(height, cls.BASIC_HEADER_SIZE)
+
+    @classmethod
+    def deserializer(cls):
+        return DeserializerZcash

lib/tx.py

@@ -238,3 +238,67 @@ class DeserializerSegWit(Deserializer):
 
         return TxSegWit(version, marker, flag, inputs,
                         outputs, witness, locktime), double_sha256(orig_ser)
+
+
+class DeserializerAuxPow(Deserializer):
+    VERSION_AUXPOW = (1 << 8)
+
+    def read_header(self, height, static_header_size):
+        '''Return the AuxPow block header bytes'''
+        start = self.cursor
+        version = self._read_le_uint32()
+        if version & self.VERSION_AUXPOW:
+            # We are going to calculate the block size then read it as bytes
+            self.cursor = start
+            self.cursor += static_header_size # Block normal header
+            self.read_tx() # AuxPow transaction
+            self.cursor += 32 # Parent block hash
+            merkle_size = self._read_varint()
+            self.cursor += 32 * merkle_size # Merkle branch
+            self.cursor += 4 # Index
+            merkle_size = self._read_varint()
+            self.cursor += 32 * merkle_size # Chain merkle branch
+            self.cursor += 4 # Chain index
+            self.cursor += 80 # Parent block header
+            header_end = self.cursor
+        else:
+            header_end = static_header_size
+        self.cursor = start
+        return self._read_nbytes(header_end)
+
+
+class TxJoinSplit(namedtuple("Tx", "version inputs outputs locktime")):
+    '''Class representing a JoinSplit transaction.'''
+
+    @cachedproperty
+    def is_coinbase(self):
+        return self.inputs[0].is_coinbase if len(self.inputs) > 0 else False
+
+
+class DeserializerZcash(Deserializer):
+    def read_header(self, height, static_header_size):
+        '''Return the block header bytes'''
+        start = self.cursor
+        # We are going to calculate the block size then read it as bytes
+        self.cursor += static_header_size
+        solution_size = self._read_varint()
+        self.cursor += solution_size
+        header_end = self.cursor
+        self.cursor = start
+        return self._read_nbytes(header_end)
+
+    def read_tx(self):
+        start = self.cursor
+        base_tx =  TxJoinSplit(
+            self._read_le_int32(),  # version
+            self._read_inputs(),    # inputs
+            self._read_outputs(),   # outputs
+            self._read_le_uint32()  # locktime
+        )
+        if base_tx.version >= 2:
+            joinsplit_size = self._read_varint()
+            if joinsplit_size > 0:
+                self.cursor += joinsplit_size * 1802 # JSDescription
+                self.cursor += 32 # joinSplitPubKey
+                self.cursor += 64 # joinSplitSig
+        return base_tx, double_sha256(self.binary[start:self.cursor])

tests/test_addresses.py

@@ -26,7 +26,7 @@
 
 import pytest
 
-from lib.coins import Litecoin, Bitcoin
+from lib.coins import Litecoin, Bitcoin, Zcash
 from lib.hash import Base58
 
 addresses = [
@@ -38,6 +38,10 @@ addresses = [
      "206168f5322583ff37f8e55665a4789ae8963532", "b8cb80b26e8932f5b12a7e"),
     (Litecoin, "3GxRZWkJufR5XA8hnNJgQ2gkASSheoBcmW",
      "a773db925b09add367dcc253c1f9bbc1d11ec6fd", "062d8515e50cb92b8a3a73"),
+    (Zcash, "t1LppKe1sfPNDMysGSGuTjxoAsBcvvSYv5j",
+     "206168f5322583ff37f8e55665a4789ae8963532", "b8cb80b26e8932f5b12a7e"),
+    (Zcash, "t3Zq2ZrASszCg7oBbio7oXqnfR6dnSWqo76",
+     "a773db925b09add367dcc253c1f9bbc1d11ec6fd", "062d8515e50cb92b8a3a73"),
 ]