security: Ensure that KeyChain::getDefaultCeritifcate() does not return 0

Change-Id: I46e4bf19d94bc4b5cf017d8305b81696e1b78ab6
Refs: #1740
diff --git a/src/security/key-chain.cpp b/src/security/key-chain.cpp
index 5118468..1d9f100 100644
--- a/src/security/key-chain.cpp
+++ b/src/security/key-chain.cpp
@@ -450,7 +450,7 @@
 {
   m_pib->refreshDefaultCertificate();
 
-  if (!static_cast<bool>(m_pib->defaultCertificate()))
+  if (!static_cast<bool>(m_pib->getDefaultCertificate()))
     {
       Name defaultIdentity;
       try