add NDNCERT_prefix and small fixes

Change-Id: I7ad5e3258599e62cce437555e64a3b461b08f8e6
diff --git a/src/detail/crypto-helper.hpp b/src/detail/crypto-helper.hpp
index 8463eb6..ecf9327 100644
--- a/src/detail/crypto-helper.hpp
+++ b/src/detail/crypto-helper.hpp
@@ -43,7 +43,7 @@
   uint8_t m_sharedSecret[256];
   size_t m_sharedSecretLen;
 
-PUBLIC_WITH_TESTS_ELSE_PRIVATE:
+NDNCERT_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
   uint8_t*
   deriveSecret(const uint8_t* peerkey, size_t peerKeySize);