Enable binary serializations of proofs and r1cs keys, and make the `CPourTx` proof field fixed-size.

configure.ac

@@ -39,10 +39,8 @@ else
   CXXFLAGS_overridden=no
 fi
 
-# Zerocash requries C++11 compatibility; set it early:
+# Zcash requries C++11 compatibility; set it early:
 CXXFLAGS="-std=c++11 $CXXFLAGS"
-# Zerocash uses this libsnark curve:
-CPPFLAGS="-DCURVE_ALT_BN128 $CPPFLAGS"
 
 AC_PROG_CXX
 m4_ifdef([AC_PROG_OBJCXX],[AC_PROG_OBJCXX])

depends/packages/libsnark.mk

@@ -15,7 +15,7 @@ define $(package)_preprocess_cmds
 endef
 
 define $(package)_build_cmds
-  CXXFLAGS="-fPIC -DNO_PT_COMPRESSION=1" $(MAKE) lib DEPINST=$(host_prefix) CURVE=ALT_BN128 NO_PROCPS=1 NO_GTEST=1 NO_DOCS=1 STATIC=1 NO_SUPERCOP=1
+  CXXFLAGS="-fPIC -DBINARY_OUTPUT -DNO_PT_COMPRESSION=1" $(MAKE) lib DEPINST=$(host_prefix) CURVE=ALT_BN128 NO_PROCPS=1 NO_GTEST=1 NO_DOCS=1 STATIC=1 NO_SUPERCOP=1
 endef
 
 define $(package)_stage_cmds

src/Makefile.am

@@ -415,7 +415,7 @@ libzcash_a_SOURCES = \
   zcash/prf.cpp \
   zcash/util.cpp
 
-libzcash_a_CPPFLAGS = -fPIC -DCURVE_ALT_BN128 -DBOOST_SPIRIT_THREADSAFE -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS $(HARDENED_CPPFLAGS) -std=c++11 -pipe -O2 -O0 -g -Wstack-protector -fstack-protector-all -fPIE -fvisibility=hidden -DSTATIC $(BITCOIN_INCLUDES)
+libzcash_a_CPPFLAGS = -fPIC -DBINARY_OUTPUT -DCURVE_ALT_BN128 -DBOOST_SPIRIT_THREADSAFE -DHAVE_BUILD_INFO -D__STDC_FORMAT_MACROS $(HARDENED_CPPFLAGS) -pipe -O2 -O0 -g -Wstack-protector -fstack-protector-all -fPIE -fvisibility=hidden -DSTATIC $(BITCOIN_INCLUDES)
 
 # bitcoinconsensus library #
 if BUILD_BITCOIN_LIBS

src/Makefile.gtest.include

@@ -11,6 +11,8 @@ zcash_gtest_SOURCES = \
 	gtest/test_merkletree.cpp \
 	gtest/test_circuit.cpp
 
+zcash_gtest_CPPFLAGS = -DBINARY_OUTPUT -DCURVE_ALT_BN128 -DSTATIC
+
 zcash_gtest_LDADD = -lgtest $(LIBBITCOIN_SERVER) $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_UNIVALUE) $(LIBLEVELDB) $(LIBMEMENV) \
   $(BOOST_LIBS) $(BOOST_UNIT_TEST_FRAMEWORK_LIB) $(LIBSECP256K1)
 if ENABLE_WALLET

src/gtest/test_joinsplit.cpp

@@ -33,7 +33,7 @@ void test_full_api(ZCJoinSplit* js)
     boost::array<uint256, 2> commitments;
     uint256 rt = tree.root();
     boost::array<ZCNoteEncryption::Ciphertext, 2> ciphertexts;
-    std::string proof;
+    boost::array<unsigned char, ZKSNARK_PROOF_SIZE> proof;
 
     {
         boost::array<JSInput, 2> inputs = {

src/primitives/transaction.h

@@ -63,7 +63,7 @@ public:
 
     // Pour proof
     // This is a zk-SNARK which ensures that this pour is valid.
-    std::string proof;
+    boost::array<unsigned char, ZKSNARK_PROOF_SIZE> proof;
 
     CPourTx(): vpub_old(0), vpub_new(0) { }
 

src/test/sighash_tests.cpp

@@ -135,14 +135,6 @@ void static RandomTransaction(CMutableTransaction &tx, bool fSingle) {
             randombytes_buf(pourtx.ciphertexts[1].begin(), pourtx.ciphertexts[1].size());
             pourtx.macs[0] = GetRandHash();
             pourtx.macs[1] = GetRandHash();
-            {
-                std::vector<unsigned char> txt;
-                int prooflen = insecure_rand() % 1000;
-                for (int i = 0; i < prooflen; i++) {
-                    txt.push_back(insecure_rand() % 256);
-                }
-                pourtx.proof = std::string(txt.begin(), txt.end());
-            }
 
             tx.vpour.push_back(pourtx);
         }

src/zcash/JoinSplit.cpp

@@ -126,7 +126,7 @@ public:
     JoinSplitCircuit() {}
 
     bool verify(
-        const std::string& proof,
+        const boost::array<unsigned char, ZKSNARK_PROOF_SIZE>& proof,
         const uint256& pubKeyHash,
         const uint256& randomSeed,
         const boost::array<uint256, NumInputs>& macs,
@@ -142,7 +142,8 @@ public:
 
         r1cs_ppzksnark_proof<ppzksnark_ppT> r1cs_proof;
         std::stringstream ss;
-        ss.str(proof);
+        std::string proof_str(proof.begin(), proof.end());
+        ss.str(proof_str);
         ss >> r1cs_proof;
 
         uint256 h_sig = this->h_sig(randomSeed, nullifiers, pubKeyHash);
@@ -160,7 +161,7 @@ public:
         return r1cs_ppzksnark_verifier_strong_IC<ppzksnark_ppT>(*vk, witness, r1cs_proof);
     }
 
-    std::string prove(
+    boost::array<unsigned char, ZKSNARK_PROOF_SIZE> prove(
         const boost::array<JSInput, NumInputs>& inputs,
         const boost::array<JSOutput, NumOutputs>& outputs,
         boost::array<Note, NumOutputs>& out_notes,
@@ -266,8 +267,14 @@ public:
 
         std::stringstream ss;
         ss << proof;
+        std::string serialized_proof = ss.str();
 
-        return ss.str();
+        boost::array<unsigned char, ZKSNARK_PROOF_SIZE> result_proof;
+        //std::cout << "proof size in bytes when serialized: " << serialized_proof.size() << std::endl;
+        assert(serialized_proof.size() == ZKSNARK_PROOF_SIZE);
+        memcpy(&result_proof[0], &serialized_proof[0], ZKSNARK_PROOF_SIZE);
+
+        return result_proof;
     }
 };
 

src/zcash/JoinSplit.hpp

@@ -58,7 +58,7 @@ public:
     virtual void loadVerifyingKey(std::string path) = 0;
     virtual void saveVerifyingKey(std::string path) = 0;
 
-    virtual std::string prove(
+    virtual boost::array<unsigned char, ZKSNARK_PROOF_SIZE> prove(
         const boost::array<JSInput, NumInputs>& inputs,
         const boost::array<JSOutput, NumOutputs>& outputs,
         boost::array<Note, NumOutputs>& out_notes,
@@ -75,7 +75,7 @@ public:
     ) = 0;
 
     virtual bool verify(
-        const std::string& proof,
+        const boost::array<unsigned char, ZKSNARK_PROOF_SIZE>& proof,
         const uint256& pubKeyHash,
         const uint256& randomSeed,
         const boost::array<uint256, NumInputs>& hmacs,

src/zcash/Zcash.h

@@ -12,4 +12,6 @@
 #define ZC_R_SIZE 32
 #define ZC_MEMO_SIZE 128
 
+#define ZKSNARK_PROOF_SIZE 584
+
 #endif // _ZCCONSTANTS_H_