Merge pull request #1439 from tomt1664/fix/check-missing-proofs

Add missing proof checks and tests

src/blindpsbt.cpp

@@ -68,11 +68,13 @@ bool CreateAssetSurjectionProof(std::vector<unsigned char>& output_proof, const
 
 bool VerifyBlindAssetProof(const uint256& asset, const std::vector<unsigned char>& proof, const CConfidentialAsset& conf_asset)
 {
+    if (conf_asset.vchCommitment.size() != CConfidentialAsset::nCommittedSize || proof.empty()) {
+        return false;
+    }
     secp256k1_surjectionproof surj_proof;
     if (secp256k1_surjectionproof_parse(secp256k1_blind_context, &surj_proof, proof.data(), proof.size()) == 0) {
         return false;
     }
-
     secp256k1_generator blinded_asset_gen;
     if (secp256k1_generator_parse(secp256k1_blind_context, &blinded_asset_gen, conf_asset.vchCommitment.data()) == 0) {
         return false;

src/confidential_validation.cpp

@@ -390,6 +390,9 @@ bool VerifyAmounts(const std::vector<CTxOut>& inputs, const CTransaction& tx, st
         }
         if (!ptxoutwit)
             return false;
+        if (asset.vchCommitment.size() != CConfidentialAsset::nCommittedSize || ptxoutwit->vchSurjectionproof.empty()) {
+            return false;
+        }
         if (secp256k1_generator_parse(secp256k1_ctx_verify_amounts, &gen, &asset.vchCommitment[0]) != 1)
             return false;
 

test/functional/feature_confidential_transactions.py

@@ -106,6 +106,44 @@ class CTTest (BitcoinTestFramework):
         # clean up blind_details
         os.remove(file_path)
 
+    def test_no_surj(self):
+        self.generate(self.nodes[0], 1)
+
+        tx_hex = self.nodes[0].createrawtransaction([], [{self.nodes[1].getnewaddress(): 1000}])
+        tx_hex = self.nodes[0].fundrawtransaction(tx_hex)['hex']
+        tx_hex = self.nodes[0].blindrawtransaction(tx_hex)
+        # coming from initial free coins: no need to sign
+        assert_equal(self.nodes[0].testmempoolaccept([tx_hex])[0]['allowed'], True) # tx is ok
+
+        # remove a surjection proof from the tx
+        tx = CTransaction()
+        tx.deserialize(io.BytesIO(bytes.fromhex(tx_hex)))
+        tx.wit.vtxoutwit[0].vchSurjectionproof = b''
+        tx_hex = tx.serialize().hex()
+
+        # Both of these make the node crash
+        assert_equal(self.nodes[0].testmempoolaccept([tx_hex])[0]['allowed'], False)
+        assert_raises_rpc_error(-26, "bad-txns-in-ne-out", self.nodes[0].sendrawtransaction, tx_hex)
+
+    def test_no_range(self):
+        self.generate(self.nodes[0], 1)
+
+        tx_hex = self.nodes[0].createrawtransaction([], [{self.nodes[1].getnewaddress(): 1000}])
+        tx_hex = self.nodes[0].fundrawtransaction(tx_hex)['hex']
+        tx_hex = self.nodes[0].blindrawtransaction(tx_hex)
+        # coming from initial free coins: no need to sign
+        assert_equal(self.nodes[0].testmempoolaccept([tx_hex])[0]['allowed'], True) # tx is ok
+
+        # remove a surjection proof from the tx
+        tx = CTransaction()
+        tx.deserialize(io.BytesIO(bytes.fromhex(tx_hex)))
+        tx.wit.vtxoutwit[0].vchRangeproof = b''
+        tx_hex = tx.serialize().hex()
+
+        # Both of these make the node crash
+        assert_equal(self.nodes[0].testmempoolaccept([tx_hex])[0]['allowed'], False)
+        assert_raises_rpc_error(-26, "bad-txns-in-ne-out", self.nodes[0].sendrawtransaction, tx_hex)
+
     def test_null_rangeproof_enforcement(self):
         self.generate(self.nodes[0], 1)
 
@@ -160,6 +198,12 @@ class CTTest (BitcoinTestFramework):
 
     def run_test(self):
 
+        print("Testing a transaction with a missing surjection proof")
+        self.test_no_surj()
+
+        print("Testing a transaction with a missing range proof")
+        self.test_no_range()
+
         print("Testing that null issuances must have null rangeproofs")
         self.test_null_rangeproof_enforcement()