Auto merge of zcash#1399 - ebfull:write-r1cs, r=ebfull

Write R1CS output to file in GenerateParams.

Not urgent. This is how the constraint system is communicated to the MPC.

src/zcash/GenerateParams.cpp

@@ -9,18 +9,20 @@ int main(int argc, char **argv)
         return 1;
     }
 
-    if(argc != 3) {
-        std::cerr << "Usage: " << argv[0] << " provingKeyFileName verificationKeyFileName" << std::endl;
+    if(argc != 4) {
+        std::cerr << "Usage: " << argv[0] << " provingKeyFileName verificationKeyFileName r1csFileName" << std::endl;
         return 1;
     }
 
     std::string pkFile = argv[1];
     std::string vkFile = argv[2];
+    std::string r1csFile = argv[3];
 
     auto p = ZCJoinSplit::Generate();
 
     p->saveProvingKey(pkFile);
     p->saveVerifyingKey(vkFile);
+    p->saveR1CS(r1csFile);
 
     delete p;
 

src/zcash/JoinSplit.cpp

@@ -112,14 +112,23 @@ class JoinSplitCircuit : public JoinSplit<NumInputs, NumOutputs> {
             throw std::runtime_error("cannot save verifying key; key doesn't exist");
         }
     }
+    void saveR1CS(std::string path) {
+        auto r1cs = generate_r1cs();
 
-    void generate() {
+        saveToFile(path, r1cs);
+    }
+
+    r1cs_constraint_system<FieldT> generate_r1cs() {
         protoboard<FieldT> pb;
 
         joinsplit_gadget<FieldT, NumInputs, NumOutputs> g(pb);
         g.generate_r1cs_constraints();
 
-        const r1cs_constraint_system<FieldT> constraint_system = pb.get_constraint_system();
+        return pb.get_constraint_system();
+    }
+
+    void generate() {
+        const r1cs_constraint_system<FieldT> constraint_system = generate_r1cs();
         r1cs_ppzksnark_keypair<ppzksnark_ppT> keypair = r1cs_ppzksnark_generator<ppzksnark_ppT>(constraint_system);
 
         pk = keypair.pk;

src/zcash/JoinSplit.hpp

@@ -62,6 +62,7 @@ class JoinSplit {
     virtual void saveProvingKey(std::string path) = 0;
     virtual void loadVerifyingKey(std::string path) = 0;
     virtual void saveVerifyingKey(std::string path) = 0;
+    virtual void saveR1CS(std::string path) = 0;
 
     virtual ZCProof prove(
         const boost::array<JSInput, NumInputs>& inputs,