ringct: use const refs as parameters where appropriate

src/ringct/rctSigs.cpp

@@ -150,7 +150,7 @@ namespace rct {
     // Gen creates a signature which proves that for some column in the keymatrix "pk"
     //   the signer knows a secret key for each row in that column
     // Ver verifies that the MG sig was created correctly        
-    mgSig MLSAG_Gen(key message, const keyM & pk, const keyV & xx, const unsigned int index, size_t dsRows) {
+    mgSig MLSAG_Gen(const key &message, const keyM & pk, const keyV & xx, const unsigned int index, size_t dsRows) {
         mgSig rv;
         size_t cols = pk.size();
         CHECK_AND_ASSERT_THROW_MES(cols >= 2, "Error! What is c if cols = 1!");
@@ -239,7 +239,7 @@ namespace rct {
     // Gen creates a signature which proves that for some column in the keymatrix "pk"
     //   the signer knows a secret key for each row in that column
     // Ver verifies that the MG sig was created correctly            
-    bool MLSAG_Ver(key message, const keyM & pk, const mgSig & rv, size_t dsRows) {
+    bool MLSAG_Ver(const key &message, const keyM & pk, const mgSig & rv, size_t dsRows) {
 
         size_t cols = pk.size();
         CHECK_AND_ASSERT_MES(cols >= 2, false, "Error! What is c if cols = 1!");

src/ringct/rctSigs.h

@@ -90,8 +90,8 @@ namespace rct {
     //   the signer knows a secret key for each row in that column
     // Ver verifies that the MG sig was created correctly
     keyV keyImageV(const keyV &xx);
-    mgSig MLSAG_Gen(key message, const keyM & pk, const keyV & xx, const unsigned int index, size_t dsRows);
-    bool MLSAG_Ver(key message, const keyM &pk, const mgSig &sig, size_t dsRows);
+    mgSig MLSAG_Gen(const key &message, const keyM & pk, const keyV & xx, const unsigned int index, size_t dsRows);
+    bool MLSAG_Ver(const key &message, const keyM &pk, const mgSig &sig, size_t dsRows);
     //mgSig MLSAG_Gen_Old(const keyM & pk, const keyV & xx, const int index);
 
     //proveRange and verRange

src/ringct/rctTypes.h

@@ -415,7 +415,7 @@ namespace rct {
     // then the value in the first 8 bytes is returned
     xmr_amount h2d(const key &test);
     //32 byte key to int[64]
-    void h2b(bits  amountb2, key & test);
+    void h2b(bits  amountb2, const key & test);
     //int[64] to 32 byte key
     void b2h(key  & amountdh, bits amountb2);
     //int[64] to uint long long