Lazily load the proving key at time of first pour.

src/zerocash/PourTransaction.cpp

@@ -132,6 +132,7 @@ void PourTransaction::init(uint16_t version_num,
                      const Coin& c_1_new,
                      const Coin& c_2_new)
 {
+    params.loadProvingKey();
     this->version = version_num;
 
     convertIntToBytesVector(v_pub_old, this->publicOldValue);

src/zerocash/ZerocashParams.cpp

@@ -127,6 +127,17 @@ ZerocashParams::ZerocashParams(
     params_vk_v1 = new zerocash_pour_verification_key<ZerocashParams::zerocash_pp>(keypair->vk);
 }
 
+ZerocashParams::ZerocashParams(
+    const unsigned int tree_depth,
+    zerocash_pour_verification_key<ZerocashParams::zerocash_pp>* p_vk_1,
+    std::string proving_key_path
+) : 
+    treeDepth(tree_depth), provingKeyPath(proving_key_path)
+{
+    params_vk_v1 = new zerocash_pour_verification_key<ZerocashParams::zerocash_pp>(*p_vk_1);
+    params_pk_v1 = NULL;
+}
+
 ZerocashParams::ZerocashParams(
     const unsigned int tree_depth,
     zerocash_pour_proving_key<ZerocashParams::zerocash_pp>* p_pk_1,

src/zerocash/ZerocashParams.h

@@ -35,6 +35,12 @@ public:
         zerocash_pour_verification_key<ZerocashParams::zerocash_pp>* p_vk_1
     );
 
+    ZerocashParams(
+        const unsigned int tree_depth,
+        zerocash_pour_verification_key<ZerocashParams::zerocash_pp>* p_vk_1,
+        std::string proving_key_path
+    );
+
     const zerocash_pour_proving_key<zerocash_pp>& getProvingKey();
     const zerocash_pour_verification_key<zerocash_pp>& getVerificationKey();
     int getTreeDepth();
@@ -49,10 +55,21 @@ public:
     static void SaveVerificationKeyToFile(const zerocash_pour_verification_key<ZerocashParams::zerocash_pp>* p_vk_1, std::string path);
     static zerocash_pour_proving_key<ZerocashParams::zerocash_pp> LoadProvingKeyFromFile(std::string path, const unsigned int tree_depth);
     static zerocash_pour_verification_key<ZerocashParams::zerocash_pp> LoadVerificationKeyFromFile(std::string path, const unsigned int tree_depth);
+
+    void loadProvingKey()
+    {
+        if (params_pk_v1 == NULL) {
+            std::cout << "loading proving key from path: " << provingKeyPath << std::endl;
+            params_pk_v1 = new zerocash_pour_proving_key<ZerocashParams::zerocash_pp>(
+                                LoadProvingKeyFromFile(provingKeyPath, treeDepth));
+            std::cout << "done loading proving key!" << std::endl;
+        }
+    }
 private:
     int treeDepth;
     zerocash_pour_proving_key<ZerocashParams::zerocash_pp>* params_pk_v1;
     zerocash_pour_verification_key<ZerocashParams::zerocash_pp>* params_vk_v1;
+    std::string provingKeyPath;
 };
 
 } /* namespace libzerocash */