improve unblinding

src/embit/liquid/pset.py

@@ -9,7 +9,7 @@ from .. import compact, hashes
 from ..psbt import *
 from collections import OrderedDict
 from io import BytesIO
-from .transaction import LTransaction, LTransactionOutput, LTransactionInput, TxOutWitness, Proof, LSIGHASH, unblind
+from .transaction import LTransaction, LTransactionOutput, LTransactionInput, TxOutWitness, Proof, RangeProof, LSIGHASH, unblind
 from . import slip77
 import hashlib, gc
 
@@ -40,10 +40,13 @@ class LInputScope(InputScope):
             return
 
         pk = slip77.blinding_key(blinding_key, self.utxo.script_pubkey)
-
-        value, asset, vbf, in_abf, extra, min_value, max_value = unblind(
-            self.utxo.ecdh_pubkey, pk.secret, self.range_proof, self.utxo.value, self.utxo.asset, self.utxo.script_pubkey
-        )
+        try:
+            value, asset, vbf, in_abf, extra, min_value, max_value = unblind(
+                self.utxo.ecdh_pubkey, pk.secret, self.range_proof, self.utxo.value, self.utxo.asset, self.utxo.script_pubkey
+            )
+        # failed to unblind
+        except:
+            return
         # verify
         gen = secp256k1.generator_generate_blinded(asset, in_abf)
         assert gen == secp256k1.generator_parse(self.utxo.asset)
@@ -169,7 +172,7 @@ class LOutputScope(OutputScope):
     def vout(self):
         return LTransactionOutput(
                     self.asset or self.asset_commitment,
-                    self.value or self.value_commitment,
+                    self.value if self.value is not None else self.value_commitment,
                     self.script_pubkey,
                     None if self.asset else self.ecdh_pubkey)
 
@@ -180,7 +183,7 @@ class LOutputScope(OutputScope):
                     self.value_commitment or self.value,
                     self.script_pubkey,
                     self.ecdh_pubkey,
-                    None if not self.surjection_proof else TxOutWitness(Proof(self.surjection_proof), Proof(self.range_proof))
+                    None if not self.surjection_proof else TxOutWitness(Proof(self.surjection_proof), RangeProof(self.range_proof))
         )
 
     def reblind(self, nonce, blinding_pubkey=None, extra_message=b""):
@@ -345,7 +348,7 @@ class PSET(PSBT):
         abfs = []
         vbfs = []
         for sc in self.inputs + blinding_outs:
-            value = sc.value or sc.utxo.value
+            value = sc.value if sc.value is not None else sc.utxo.value
             asset = sc.asset or sc.utxo.asset
             if not (isinstance(value, int) and len(asset) == 32):
                 continue

src/embit/liquid/transaction.py

@@ -98,6 +98,14 @@ class Proof(EmbitBase):
         return cls(data)
 
 
+class RangeProof(Proof):
+
+    def unblind(self, ecdh_pubkey, blinding_key, value, asset, script_pubkey, message_length=64):
+        if not self.data:
+            raise TransactionError("Rangeproof is empty")
+        return unblind(ecdh_pubkey, blinding_key, self.data, value, asset, script_pubkey, message_length)
+
+
 class TxInWitness(EmbitBase):
     def __init__(self, amount_proof=None, token_proof=None, script_witness=None, pegin_witness=None):
         self.amount_proof = amount_proof if amount_proof is not None else Proof()
@@ -123,7 +131,7 @@ class TxInWitness(EmbitBase):
 class TxOutWitness(EmbitBase):
     def __init__(self, surjection_proof=None, range_proof=None):
         self.surjection_proof = surjection_proof if surjection_proof is not None else Proof()
-        self.range_proof = range_proof if range_proof is not None else Proof()
+        self.range_proof = range_proof if range_proof is not None else RangeProof()
 
     def write_to(self, stream):
         res = self.surjection_proof.write_to(stream)
@@ -136,7 +144,7 @@ class TxOutWitness(EmbitBase):
 
     @classmethod
     def read_from(cls, stream):
-        return cls(Proof.read_from(stream), Proof.read_from(stream))
+        return cls(Proof.read_from(stream), RangeProof.read_from(stream))
 
 
 class LTransaction(Transaction):

src/embit/util/ctypes_secp256k1.py

@@ -856,6 +856,8 @@ def rangeproof_rewind(proof, nonce, value_commitment, script_pubkey, generator,
 
 @locked
 def rangeproof_sign(nonce, value, value_commitment, vbf, message, extra, gen, min_value=1, exp=0, min_bits=52, context=_secp.ctx):
+    if value == 0:
+        min_value = 0
     if len(gen)!=64:
         raise ValueError("Generator should be 64 bytes long")
     if len(nonce)!=32: