Generate some v5 coinbase transactions.

Co-authored-by: Kris Nuttycombe <kris@nutty.land>
Signed-off-by: Daira Hopwood <daira@jacaranda.org>

zcash_test_vectors/transaction.py

@@ -160,6 +160,8 @@ class OutputDescription(object):
 
 class OrchardActionDescription(object):
     def __init__(self, rand):
+        # We don't need to take account of whether this is a coinbase transaction,
+        # because we're only generating random fields.
         self.cv = pallas_group_hash(b'TVRandPt', rand.b(32))
         self.nullifier = PallasBase(leos2ip(rand.b(32)))
         self.rk = pallas_group_hash(b'TVRandPt', rand.b(32))
@@ -220,11 +222,18 @@ RAND_OPCODES = [
 ]
 
 class Script(object):
-    def __init__(self, rand):
+    def __init__(self, rand=None):
+        if rand is not None:
             self._script = bytes([
                 rand.a(RAND_OPCODES) for i in range(rand.i8() % 10)
             ])
 
+    @staticmethod
+    def from_bytes(b):
+        script = Script()
+        script._script = b
+        return script
+
     def raw(self):
         return self._script
 
@@ -233,20 +242,37 @@ class Script(object):
 
 
 class OutPoint(object):
-    def __init__(self, rand):
+    def __init__(self, rand=None):
+        if rand is not None:
             self.txid = rand.b(32)
             self.n = rand.u32()
 
+    @staticmethod
+    def from_components(txid, n):
+        outpoint = OutPoint()
+        outpoint.txid = txid
+        outpoint.n = n
+        return outpoint
+
     def __bytes__(self):
         return self.txid + struct.pack('<I', self.n)
 
 
 class TxIn(object):
-    def __init__(self, rand):
+    def __init__(self, rand=None):
+        if rand is not None:
             self.prevout = OutPoint(rand)
             self.scriptSig = Script(rand)
             self.nSequence = rand.u32()
 
+    @staticmethod
+    def from_components(prevout, scriptSig, nSequence):
+        txin = TxIn()
+        txin.prevout = prevout
+        txin.scriptSig = scriptSig
+        txin.nSequence = nSequence
+        return txin
+
     def __bytes__(self):
         return (
             bytes(self.prevout) +
@@ -372,6 +398,7 @@ class TransactionV5(object):
         have_transparent_out = (flip_coins >> 1) % 2
         have_sapling = (flip_coins >> 2) % 2
         have_orchard = (flip_coins >> 3) % 2
+        is_coinbase = (not have_transparent_in) and (flip_coins >> 4) % 2
 
         # Common Transaction Fields
         self.nVersionGroupId = NU5_VERSION_GROUP_ID
@@ -385,6 +412,11 @@ class TransactionV5(object):
         if have_transparent_in:
             for _ in range((rand.u8() % 3) + 1):
                 self.vin.append(TxIn(rand))
+        if is_coinbase:
+            self.vin.append(TxIn.from_components(
+                OutPoint.from_components(b'\x00' * 32, 0xFFFFFFFF),
+                Script.from_bytes(b"\x51"),
+                0))
         if have_transparent_out:
             for _ in range((rand.u8() % 3) + 1):
                 self.vout.append(TxOut(rand))
@@ -394,8 +426,11 @@ class TransactionV5(object):
         self.vOutputsSapling = []
         if have_sapling:
             self.anchorSapling = Fq(leos2ip(rand.b(32)))
+            # We use the randomness unconditionally here to avoid unnecessary test vector changes.
             for _ in range(rand.u8() % 3):
-                self.vSpendsSapling.append(SpendDescription(rand, self.anchorSapling))
+                spend = SpendDescription(rand, self.anchorSapling)
+                if not is_coinbase:
+                    self.vSpendsSapling.append(spend)
             for _ in range(rand.u8() % 3):
                 self.vOutputsSapling.append(OutputDescription(rand))
             self.valueBalanceSapling = rand.u64() % (MAX_MONEY + 1)
@@ -411,6 +446,9 @@ class TransactionV5(object):
             for _ in range(rand.u8() % 5):
                 self.vActionsOrchard.append(OrchardActionDescription(rand))
             self.flagsOrchard = rand.u8() & 3 # Only two flag bits are currently defined.
+            if is_coinbase:
+                # set enableSpendsOrchard = 0
+                self.flagsOrchard &= 2
             self.valueBalanceOrchard = rand.u64() % (MAX_MONEY + 1)
             self.anchorOrchard = PallasBase(leos2ip(rand.b(32)))
             self.proofsOrchard = rand.b(rand.u8() + 32) # Proof will always contain at least one element
@@ -420,6 +458,8 @@ class TransactionV5(object):
             # v^balanceOrchard is defined to be 0.
             self.valueBalanceOrchard = 0
 
+        assert is_coinbase == self.is_coinbase()
+
     def version_bytes(self):
         return NU5_TX_VERSION | (1 << 31)
 

zcash_test_vectors/zip_0244.py

@@ -356,10 +356,13 @@ def main():
         txid = txid_digest(tx)
         auth = auth_digest(tx)
 
-        # Generate amounts and scriptCodes for each transparent input.
+        # Generate amounts and scriptCodes for each non-dummy transparent input.
+        if tx.is_coinbase():
+            t_inputs = []
+        else:
             t_inputs = [TransparentInput(nIn, rand) for nIn in range(len(tx.vin))]
 
-        # If there are any transparent inputs, derive a corresponding transparent sighash.
+        # If there are any non-dummy transparent inputs, derive a corresponding transparent sighash.
         if len(t_inputs) > 0:
             txin = rand.a(t_inputs)
         else: