From 03bff15fe2f344ea82059ffcc0e5425ad2de80b0 Mon Sep 17 00:00:00 2001
From: Sean Bowe <ewillbefull@gmail.com>
Date: Fri, 8 Jan 2016 02:00:54 -0700
Subject: [PATCH] Enforce zk-SNARK validity during consensus.

---
 src/consensus/validation.h     |  9 ++++++++-
 src/main.cpp                   | 11 +++++++++++
 src/test/sighash_tests.cpp     |  1 +
 src/test/transaction_tests.cpp |  3 +++
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/consensus/validation.h b/src/consensus/validation.h
index c92bec4fa..68ac41632 100644
--- a/src/consensus/validation.h
+++ b/src/consensus/validation.h
@@ -30,8 +30,9 @@ private:
     std::string strRejectReason;
     unsigned char chRejectCode;
     bool corruptionPossible;
+    bool pourVerify;
 public:
-    CValidationState() : mode(MODE_VALID), nDoS(0), chRejectCode(0), corruptionPossible(false) {}
+    CValidationState() : mode(MODE_VALID), nDoS(0), chRejectCode(0), corruptionPossible(false), pourVerify(true) {}
     bool DoS(int level, bool ret = false,
              unsigned char chRejectCodeIn=0, std::string strRejectReasonIn="",
              bool corruptionIn=false) {
@@ -44,6 +45,12 @@ public:
         mode = MODE_INVALID;
         return ret;
     }
+    bool SetPerformPourVerification(bool pourVerifyIn) {
+        pourVerify = pourVerifyIn;
+    }
+    bool PerformPourVerification() {
+        return pourVerify;
+    }
     bool Invalid(bool ret = false,
                  unsigned char _chRejectCode=0, std::string _strRejectReason="") {
         return DoS(0, ret, _chRejectCode, _strRejectReason);
diff --git a/src/main.cpp b/src/main.cpp
index b3b1149ac..e8094d90e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -945,6 +945,17 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state)
             if (txin.prevout.IsNull())
                 return state.DoS(10, error("CheckTransaction(): prevout is null"),
                                  REJECT_INVALID, "bad-txns-prevout-null");
+
+        // Ensure that zk-SNARKs verify
+
+        if (state.PerformPourVerification()) {
+            BOOST_FOREACH(const CPourTx &pour, tx.vpour) {
+                if (!pour.Verify(*pzerocashParams)) {
+                    return state.DoS(100, error("CheckTransaction(): pour does not verify"),
+                                     REJECT_INVALID, "bad-txns-pour-verification-failed");
+                }
+            }
+        }
     }
 
     return true;
diff --git a/src/test/sighash_tests.cpp b/src/test/sighash_tests.cpp
index d8dda22eb..d9ddf741a 100644
--- a/src/test/sighash_tests.cpp
+++ b/src/test/sighash_tests.cpp
@@ -227,6 +227,7 @@ BOOST_AUTO_TEST_CASE(sighash_from_data)
           stream >> tx;
 
           CValidationState state;
+          state.SetPerformPourVerification(false); // don't verify the snark
           BOOST_CHECK_MESSAGE(CheckTransaction(tx, state), strTest);
           BOOST_CHECK(state.IsValid());
 
diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
index 7ecbd97d5..91b03f7ff 100644
--- a/src/test/transaction_tests.cpp
+++ b/src/test/transaction_tests.cpp
@@ -391,6 +391,9 @@ BOOST_AUTO_TEST_CASE(test_simple_pour_invalidity)
         // pours.
         CMutableTransaction newTx(tx);
         CValidationState state;
+
+        state.SetPerformPourVerification(false); // don't verify the snark
+
         // No pours, vin and vout, means it should be invalid.
         BOOST_CHECK(!CheckTransaction(newTx, state));
         BOOST_CHECK(state.GetRejectReason() == "bad-txns-vin-empty");