security: Bug fixing

1. correct the error message for non-existing public key.
2. rename private key export/import methods to avoid confusion.

Refs: #1527

Change-Id: I3ea8378378a66e1fbec7f0d4f210057c8f9b969b
diff --git a/src/security/key-chain.hpp b/src/security/key-chain.hpp
index 1a76d1a..5143a4a 100644
--- a/src/security/key-chain.hpp
+++ b/src/security/key-chain.hpp
@@ -511,14 +511,14 @@
 
     Name keyName = Info::getDefaultKeyNameForIdentity(identity);
 
-    ConstBufferPtr pkcs8;
+    ConstBufferPtr pkcs5;
     try
       {
-        pkcs8 = Tpm::exportPrivateKeyPkcs8FromTpm(keyName, passwordStr);
+        pkcs5 = Tpm::exportPrivateKeyPkcs5FromTpm(keyName, passwordStr);
       }
     catch (TpmError& e)
       {
-        throw InfoError("Fail to export PKCS8 of private key");
+        throw InfoError("Fail to export PKCS5 of private key");
       }
 
     shared_ptr<IdentityCertificate> cert;
@@ -533,7 +533,7 @@
       }
 
     shared_ptr<SecuredBag> secureBag = make_shared<SecuredBag>(boost::cref(*cert),
-                                                               boost::cref(pkcs8));
+                                                               boost::cref(pkcs5));
 
     return secureBag;
   }
@@ -555,7 +555,7 @@
     Info::addIdentity(identity);
 
     // Add key
-    Tpm::importPrivateKeyPkcs8IntoTpm(keyName,
+    Tpm::importPrivateKeyPkcs5IntoTpm(keyName,
                                       securedBag.getKey()->buf(),
                                       securedBag.getKey()->size(),
                                       passwordStr);